Commit | Line | Data |
---|---|---|
6e2f6f45 | 1 | ;;; advice.el --- an overloading mechanism for Emacs Lisp functions |
ee7bf2ad | 2 | |
6e2f6f45 | 3 | ;; Copyright (C) 1993, 1994 Free Software Foundation, Inc. |
ee7bf2ad RM |
4 | |
5 | ;; Author: Hans Chalupsky <hans@cs.buffalo.edu> | |
6 | ;; Created: 12 Dec 1992 | |
81eee8ab | 7 | ;; Version: advice.el,v 2.14 1994/08/05 03:42:04 hans Exp |
b7f66977 | 8 | ;; Keywords: extensions, lisp, tools |
ee7bf2ad RM |
9 | |
10 | ;; This file is part of GNU Emacs. | |
11 | ||
12 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
13 | ;; it under the terms of the GNU General Public License as published by | |
14 | ;; the Free Software Foundation; either version 2, or (at your option) | |
15 | ;; any later version. | |
16 | ||
17 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
18 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | ;; GNU General Public License for more details. | |
21 | ||
22 | ;; You should have received a copy of the GNU General Public License | |
23 | ;; along with GNU Emacs; see the file COPYING. If not, write to | |
24 | ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. | |
25 | ||
26 | ;; LCD Archive Entry: | |
27 | ;; advice|Hans Chalupsky|hans@cs.buffalo.edu| | |
6e2f6f45 | 28 | ;; Overloading mechanism for Emacs Lisp functions| |
81eee8ab | 29 | ;; 1994/08/05 03:42:04|2.14|~/packages/advice.el.Z| |
ee7bf2ad RM |
30 | |
31 | ||
32 | ;;; Commentary: | |
33 | ||
6e2f6f45 RS |
34 | ;; NOTE: This documentation is slightly out of date. In particular, all the |
35 | ;; references to Emacs-18 are obsolete now, because it is not any longer | |
36 | ;; supported by this version of Advice. An up-to-date version will soon be | |
37 | ;; available as an info file (thanks to the kind help of Jack Vinson and | |
38 | ;; David M. Smith). | |
39 | ||
ee7bf2ad RM |
40 | ;; @ Introduction: |
41 | ;; =============== | |
42 | ;; This package implements a full-fledged Lisp-style advice mechanism | |
43 | ;; for Emacs Lisp. Advice is a clean and efficient way to modify the | |
44 | ;; behavior of Emacs Lisp functions without having to keep personal | |
45 | ;; modified copies of such functions around. A great number of such | |
46 | ;; modifications can be achieved by treating the original function as a | |
47 | ;; black box and specifying a different execution environment for it | |
48 | ;; with a piece of advice. Think of a piece of advice as a kind of fancy | |
49 | ;; hook that you can attach to any function/macro/subr. | |
50 | ||
51 | ;; @ Highlights: | |
52 | ;; ============= | |
53 | ;; - Clean definition of multiple, named before/around/after advices | |
54 | ;; for functions, macros, subrs and special forms | |
55 | ;; - Full control over the arguments an advised function will receive, | |
56 | ;; the binding environment in which it will be executed, as well as the | |
57 | ;; value it will return. | |
58 | ;; - Allows re/definition of interactive behavior for functions and subrs | |
59 | ;; - Every piece of advice can have its documentation string which will be | |
60 | ;; combined with the original documentation of the advised function at | |
61 | ;; call-time of `documentation' for proper command-key substitution. | |
62 | ;; - The execution of every piece of advice can be protected against error | |
63 | ;; and non-local exits in preceding code or advices. | |
64 | ;; - Simple argument access either by name, or, more portable but as | |
65 | ;; efficient, via access macros | |
66 | ;; - Allows the specification of a different argument list for the advised | |
67 | ;; version of a function. | |
68 | ;; - Advised functions can be byte-compiled either at file-compile time | |
69 | ;; (see preactivation) or activation time. | |
70 | ;; - Separation of advice definition and activation | |
fabaa9b5 | 71 | ;; - Forward advice is possible, that is |
ee7bf2ad RM |
72 | ;; as yet undefined or autoload functions can be advised without having to |
73 | ;; preload the file in which they are defined. | |
74 | ;; - Forward redefinition is possible because around advice can be used to | |
75 | ;; completely redefine a function. | |
76 | ;; - A caching mechanism for advised definition provides for cheap deactivation | |
77 | ;; and reactivation of advised functions. | |
78 | ;; - Preactivation allows efficient construction and compilation of advised | |
79 | ;; definitions at file compile time without giving up the flexibility of | |
80 | ;; the advice mechanism. | |
81 | ;; - En/disablement mechanism allows the use of different "views" of advised | |
82 | ;; functions depending on what pieces of advice are currently en/disabled | |
83 | ;; - Provides manipulation mechanisms for sets of advised functions via | |
84 | ;; regular expressions that match advice names | |
ee7bf2ad | 85 | |
6e2f6f45 RS |
86 | ;; @ How to get Advice for Emacs-18: |
87 | ;; ================================= | |
88 | ;; `advice18.el', a version of Advice that also works in Emacs-18 is available | |
89 | ;; either via anonymous ftp from `ftp.cs.buffalo.edu (128.205.32.9)' with | |
90 | ;; pathname `/pub/Emacs/advice18.el', or from one of the Emacs Lisp archive | |
91 | ;; sites, or send email to <hans@cs.buffalo.edu> and I'll mail it to you. | |
ee7bf2ad RM |
92 | |
93 | ;; @ Overview, or how to read this file: | |
94 | ;; ===================================== | |
6e2f6f45 RS |
95 | ;; NOTE: This documentation is slightly out of date. In particular, all the |
96 | ;; references to Emacs-18 are obsolete now, because it is not any longer | |
97 | ;; supported by this version of Advice. An up-to-date version will soon be | |
98 | ;; available as an info file (thanks to the kind help of Jack Vinson and | |
99 | ;; David M. Smith). Until then you can use `outline-mode' to help you read | |
100 | ;; this documentation (set `outline-regexp' to `";; @+"'). | |
ee7bf2ad RM |
101 | ;; |
102 | ;; The four major sections of this file are: | |
103 | ;; | |
104 | ;; @ This initial information ...installation, customization etc. | |
105 | ;; @ Advice documentation: ...general documentation | |
6e2f6f45 | 106 | ;; @ Foo games: An advice tutorial ...teaches about Advice by example |
ee7bf2ad RM |
107 | ;; @ Advice implementation: ...actual code, yeah!! |
108 | ;; | |
109 | ;; The latter three are actual headings which you can search for | |
6e2f6f45 | 110 | ;; directly in case `outline-mode' doesn't work for you. |
ee7bf2ad RM |
111 | |
112 | ;; @ Restrictions: | |
113 | ;; =============== | |
fabaa9b5 RS |
114 | ;; - This version of Advice only works for Emacs 19.26 and later. It uses |
115 | ;; new versions of the built-in functions `fset/defalias' which are not | |
116 | ;; yet available in Lucid Emacs, hence, it won't work there. | |
ee7bf2ad RM |
117 | ;; - Advised functions/macros/subrs will only exhibit their advised behavior |
118 | ;; when they are invoked via their function cell. This means that advice will | |
119 | ;; not work for the following: | |
120 | ;; + advised subrs that are called directly from other subrs or C-code | |
121 | ;; + advised subrs that got replaced with their byte-code during | |
122 | ;; byte-compilation (e.g., car) | |
123 | ;; + advised macros which were expanded during byte-compilation before | |
124 | ;; their advice was activated. | |
6e2f6f45 | 125 | |
ee7bf2ad RM |
126 | ;; @ Credits: |
127 | ;; ========== | |
128 | ;; This package is an extension and generalization of packages such as | |
129 | ;; insert-hooks.el written by Noah S. Friedman, and advise.el written by | |
130 | ;; Raul J. Acevedo. Some ideas used in here come from these packages, | |
131 | ;; others come from the various Lisp advice mechanisms I've come across | |
132 | ;; so far, and a few are simply mine. | |
133 | ||
134 | ;; @ Comments, suggestions, bug reports: | |
135 | ;; ===================================== | |
136 | ;; If you find any bugs, have suggestions for new advice features, find the | |
137 | ;; documentation wrong, confusing, incomplete, or otherwise unsatisfactory, | |
6e2f6f45 | 138 | ;; have any questions about Advice, or have otherwise enlightening |
ee7bf2ad RM |
139 | ;; comments feel free to send me email at <hans@cs.buffalo.edu>. |
140 | ||
141 | ;; @ Safety Rules and Emergency Exits: | |
142 | ;; =================================== | |
143 | ;; Before we begin: CAUTION!! | |
6e2f6f45 | 144 | ;; Advice provides you with a lot of rope to hang yourself on very |
ee7bf2ad | 145 | ;; easily accessible trees, so, here are a few important things you |
fabaa9b5 RS |
146 | ;; should know: Once Advice has been started with `ad-start-advice' |
147 | ;; (which happens automatically when you load this file), it | |
148 | ;; generates an advised definition of the `documentation' function, and | |
149 | ;; it will enable automatic advice activation when functions get defined. | |
150 | ;; All of this can be undone at any time with `M-x ad-stop-advice'. | |
ee7bf2ad RM |
151 | ;; |
152 | ;; If you experience any strange behavior/errors etc. that you attribute to | |
6e2f6f45 | 153 | ;; Advice or to some ill-advised function do one of the following: |
ee7bf2ad RM |
154 | |
155 | ;; - M-x ad-deactivate FUNCTION (if you have a definite suspicion what | |
156 | ;; function gives you problems) | |
157 | ;; - M-x ad-deactivate-all (if you don't have a clue what's going wrong) | |
158 | ;; - M-x ad-stop-advice (if you think the problem is related to the | |
6e2f6f45 | 159 | ;; advised functions used by Advice itself) |
ee7bf2ad | 160 | ;; - M-x ad-recover-normality (for real emergencies) |
6e2f6f45 | 161 | ;; - If none of the above solves your Advice-related problem go to another |
ee7bf2ad RM |
162 | ;; terminal, kill your Emacs process and send me some hate mail. |
163 | ||
164 | ;; The first three measures have restarts, i.e., once you've figured out | |
165 | ;; the problem you can reactivate advised functions with either `ad-activate', | |
166 | ;; `ad-activate-all', or `ad-start-advice'. `ad-recover-normality' unadvises | |
167 | ;; everything so you won't be able to reactivate any advised functions, you'll | |
168 | ;; have to stick with their standard incarnations for the rest of the session. | |
169 | ||
6e2f6f45 | 170 | ;; IMPORTANT: With Advice loaded always do `M-x ad-deactivate-all' before |
ee7bf2ad RM |
171 | ;; you byte-compile a file, because advised special forms and macros can lead |
172 | ;; to unwanted compilation results. When you are done compiling use | |
173 | ;; `M-x ad-activate-all' to go back to the advised state of all your | |
174 | ;; advised functions. | |
175 | ||
6e2f6f45 | 176 | ;; RELAX: Advice is pretty safe even if you are oblivious to the above. |
ee7bf2ad RM |
177 | ;; I use it extensively and haven't run into any serious trouble in a long |
178 | ;; time. Just wanted you to be warned. | |
179 | ||
ee7bf2ad RM |
180 | ;; @ Customization: |
181 | ;; ================ | |
ee7bf2ad | 182 | |
ee7bf2ad RM |
183 | ;; Look at the documentation of `ad-redefinition-action' for possible values |
184 | ;; of this variable. Its default value is `warn' which will print a warning | |
185 | ;; message when an already defined advised function gets redefined with a | |
186 | ;; new original definition and de/activated. | |
187 | ||
fabaa9b5 RS |
188 | ;; Look at the documentation of `ad-default-compilation-action' for possible |
189 | ;; values of this variable. Its default value is `maybe' which will compile | |
190 | ;; advised definitions during activation in case the byte-compiler is already | |
191 | ;; loaded. Otherwise, it will leave them uncompiled. | |
192 | ||
ee7bf2ad RM |
193 | ;; @ Motivation: |
194 | ;; ============= | |
195 | ;; Before I go on explaining how advice works, here are four simple examples | |
196 | ;; how this package can be used. The first three are very useful, the last one | |
197 | ;; is just a joke: | |
198 | ||
199 | ;;(defadvice switch-to-buffer (before existing-buffers-only activate) | |
200 | ;; "When called interactively switch to existing buffers only, unless | |
201 | ;;when called with a prefix argument." | |
202 | ;; (interactive | |
203 | ;; (list (read-buffer "Switch to buffer: " (other-buffer) | |
204 | ;; (null current-prefix-arg))))) | |
205 | ;; | |
206 | ;;(defadvice switch-to-buffer (around confirm-non-existing-buffers activate) | |
207 | ;; "Switch to non-existing buffers only upon confirmation." | |
208 | ;; (interactive "BSwitch to buffer: ") | |
209 | ;; (if (or (get-buffer (ad-get-arg 0)) | |
210 | ;; (y-or-n-p (format "`%s' does not exist, create? " (ad-get-arg 0)))) | |
211 | ;; ad-do-it)) | |
212 | ;; | |
213 | ;;(defadvice find-file (before existing-files-only activate) | |
214 | ;; "Find existing files only" | |
215 | ;; (interactive "fFind file: ")) | |
216 | ;; | |
217 | ;;(defadvice car (around interactive activate) | |
218 | ;; "Make `car' an interactive function." | |
219 | ;; (interactive "xCar of list: ") | |
220 | ;; ad-do-it | |
221 | ;; (if (interactive-p) | |
222 | ;; (message "%s" ad-return-value))) | |
223 | ||
224 | ||
225 | ;; @ Advice documentation: | |
226 | ;; ======================= | |
227 | ;; Below is general documentation of the various features of advice. For more | |
228 | ;; concrete examples check the corresponding sections in the tutorial part. | |
229 | ||
230 | ;; @@ Terminology: | |
231 | ;; =============== | |
6e2f6f45 | 232 | ;; - Emacs, Emacs-19: FSF's version of Emacs with major version 19 |
ee7bf2ad RM |
233 | ;; - Lemacs: Lucid's version of Emacs with major version 19 |
234 | ;; - v18: Any Emacs with major version 18 or built as an extension to that | |
235 | ;; (such as Epoch) | |
236 | ;; - v19: Any Emacs with major version 19 | |
237 | ;; - jwz: Jamie Zawinski - keeper of Lemacs and creator of the optimizing | |
238 | ;; byte-compiler used in v19s. | |
6e2f6f45 | 239 | ;; - Advice: The name of this package. |
ee7bf2ad RM |
240 | ;; - advices: Short for "pieces of advice". |
241 | ||
242 | ;; @@ Defining a piece of advice with `defadvice': | |
243 | ;; =============================================== | |
244 | ;; The main means of defining a piece of advice is the macro `defadvice', | |
245 | ;; there is no interactive way of specifying a piece of advice. A call to | |
246 | ;; `defadvice' has the following syntax which is similar to the syntax of | |
247 | ;; `defun/defmacro': | |
248 | ;; | |
249 | ;; (defadvice <function> (<class> <name> [<position>] [<arglist>] {<flags>}*) | |
250 | ;; [ [<documentation-string>] [<interactive-form>] ] | |
251 | ;; {<body-form>}* ) | |
252 | ||
253 | ;; <function> is the name of the function/macro/subr to be advised. | |
254 | ||
255 | ;; <class> is the class of the advice which has to be one of `before', | |
256 | ;; `around', `after', `activation' or `deactivation' (the last two allow | |
257 | ;; definition of special act/deactivation hooks). | |
258 | ||
6e2f6f45 | 259 | ;; <name> is the name of the advice which has to be a non-nil symbol. |
ee7bf2ad RM |
260 | ;; Names uniquely identify a piece of advice in a certain advice class, |
261 | ;; hence, advices can be redefined by defining an advice with the same class | |
262 | ;; and name. Advice names are global symbols, hence, the same name space | |
263 | ;; conventions used for function names should be applied. | |
264 | ||
265 | ;; An optional <position> specifies where in the current list of advices of | |
266 | ;; the specified <class> this new advice will be placed. <position> has to | |
267 | ;; be either `first', `last' or a number that specifies a zero-based | |
268 | ;; position (`first' is equivalent to 0). If no position is specified | |
269 | ;; `first' will be used as a default. If this call to `defadvice' redefines | |
270 | ;; an already existing advice (see above) then the position argument will | |
271 | ;; be ignored and the position of the already existing advice will be used. | |
272 | ||
273 | ;; An optional <arglist> which has to be a list can be used to define the | |
274 | ;; argument list of the advised function. This argument list should of | |
275 | ;; course be compatible with the argument list of the original function, | |
276 | ;; otherwise functions that call the advised function with the original | |
277 | ;; argument list in mind will break. If more than one advice specify an | |
278 | ;; argument list then the first one (the one with the smallest position) | |
279 | ;; found in the list of before/around/after advices will be used. | |
280 | ||
281 | ;; <flags> is a list of symbols that specify further information about the | |
282 | ;; advice. All flags can be specified with unambiguous initial substrings. | |
283 | ;; `activate': Specifies that the advice information of the advised | |
284 | ;; function should be activated right after this advice has been | |
285 | ;; defined. In forward advices `activate' will be ignored. | |
286 | ;; `protect': Specifies that this advice should be protected against | |
287 | ;; non-local exits and errors in preceding code/advices. | |
288 | ;; `compile': Specifies that the advised function should be byte-compiled. | |
289 | ;; This flag will be ignored unless `activate' is also specified. | |
290 | ;; `disable': Specifies that the defined advice should be disabled, hence, | |
291 | ;; it will not be used in an activation until somebody enables it. | |
292 | ;; `preactivate': Specifies that the advised function should get preactivated | |
293 | ;; at macro-expansion/compile time of this `defadvice'. This | |
294 | ;; generates a compiled advised definition according to the | |
295 | ;; current advice state which will be used during activation | |
296 | ;; if appropriate. Only use this if the `defadvice' gets | |
297 | ;; actually compiled (with a v18 byte-compiler put the `defadvice' | |
298 | ;; into the body of a `defun' to accomplish proper compilation). | |
299 | ||
300 | ;; An optional <documentation-string> can be supplied to document the advice. | |
301 | ;; On call of the `documentation' function it will be combined with the | |
302 | ;; documentation strings of the original function and other advices. | |
303 | ||
304 | ;; An optional <interactive-form> form can be supplied to change/add | |
305 | ;; interactive behavior of the original function. If more than one advice | |
306 | ;; has an `(interactive ...)' specification then the first one (the one | |
307 | ;; with the smallest position) found in the list of before/around/after | |
308 | ;; advices will be used. | |
309 | ||
310 | ;; A possibly empty list of <body-forms> specifies the body of the advice in | |
311 | ;; an implicit progn. The body of an advice can access/change arguments, | |
312 | ;; the return value, the binding environment, and can have all sorts of | |
313 | ;; other side effects. | |
314 | ||
315 | ;; @@ Assembling advised definitions: | |
316 | ;; ================================== | |
317 | ;; Suppose a function/macro/subr/special-form has N pieces of before advice, | |
318 | ;; M pieces of around advice and K pieces of after advice. Assuming none of | |
319 | ;; the advices is protected, its advised definition will look like this | |
320 | ;; (body-form indices correspond to the position of the respective advice in | |
321 | ;; that advice class): | |
322 | ||
323 | ;; ([macro] lambda <arglist> | |
324 | ;; [ [<advised-docstring>] [(interactive ...)] ] | |
325 | ;; (let (ad-return-value) | |
326 | ;; {<before-0-body-form>}* | |
327 | ;; .... | |
328 | ;; {<before-N-1-body-form>}* | |
329 | ;; {<around-0-body-form>}* | |
330 | ;; {<around-1-body-form>}* | |
331 | ;; .... | |
332 | ;; {<around-M-1-body-form>}* | |
333 | ;; (setq ad-return-value | |
334 | ;; <apply original definition to <arglist>>) | |
335 | ;; {<other-around-M-1-body-form>}* | |
336 | ;; .... | |
337 | ;; {<other-around-1-body-form>}* | |
338 | ;; {<other-around-0-body-form>}* | |
339 | ;; {<after-0-body-form>}* | |
340 | ;; .... | |
341 | ;; {<after-K-1-body-form>}* | |
342 | ;; ad-return-value)) | |
343 | ||
344 | ;; Macros and special forms will be redefined as macros, hence the optional | |
345 | ;; [macro] in the beginning of the definition. | |
346 | ||
347 | ;; <arglist> is either the argument list of the original function or the | |
348 | ;; first argument list defined in the list of before/around/after advices. | |
349 | ;; The values of <arglist> variables can be accessed/changed in the body of | |
350 | ;; an advice by simply referring to them by their original name, however, | |
351 | ;; more portable argument access macros are also provided (see below). For | |
352 | ;; subrs/special-forms for which neither explicit argument list definitions | |
353 | ;; are available, nor their documentation strings contain such definitions | |
354 | ;; (as they do v19s), `(&rest ad-subr-args)' will be used. | |
355 | ||
356 | ;; <advised-docstring> is an optional, special documentation string which will | |
357 | ;; be expanded into a proper documentation string upon call of `documentation'. | |
358 | ||
359 | ;; (interactive ...) is an optional interactive form either taken from the | |
360 | ;; original function or from a before/around/after advice. For advised | |
361 | ;; interactive subrs that do not have an interactive form specified in any | |
362 | ;; advice we have to use (interactive) and then call the subr interactively | |
363 | ;; if the advised function was called interactively, because the | |
364 | ;; interactive specification of subrs is not accessible. This is the only | |
365 | ;; case where changing the values of arguments will not have an affect | |
366 | ;; because they will be reset by the interactive specification of the subr. | |
367 | ;; If this is a problem one can always specify an interactive form in a | |
368 | ;; before/around/after advice to gain control over argument values that | |
369 | ;; were supplied interactively. | |
370 | ;; | |
371 | ;; Then the body forms of the various advices in the various classes of advice | |
372 | ;; are assembled in order. The forms of around advice L are normally part of | |
373 | ;; one of the forms of around advice L-1. An around advice can specify where | |
374 | ;; the forms of the wrapped or surrounded forms should go with the special | |
375 | ;; keyword `ad-do-it', which will be substituted with a `progn' containing the | |
376 | ;; forms of the surrounded code. | |
377 | ||
378 | ;; The innermost part of the around advice onion is | |
379 | ;; <apply original definition to <arglist>> | |
380 | ;; whose form depends on the type of the original function. The variable | |
381 | ;; `ad-return-value' will be set to its result. This variable is visible to | |
382 | ;; all pieces of advice which can access and modify it before it gets returned. | |
383 | ;; | |
384 | ;; The semantic structure of advised functions that contain protected pieces | |
385 | ;; of advice is the same. The only difference is that `unwind-protect' forms | |
386 | ;; make sure that the protected advice gets executed even if some previous | |
387 | ;; piece of advice had an error or a non-local exit. If any around advice is | |
388 | ;; protected then the whole around advice onion will be protected. | |
389 | ||
390 | ;; @@ Argument access in advised functions: | |
391 | ;; ======================================== | |
392 | ;; As already mentioned, the simplest way to access the arguments of an | |
393 | ;; advised function in the body of an advice is to refer to them by name. To | |
394 | ;; do that, the advice programmer needs to know either the names of the | |
395 | ;; argument variables of the original function, or the names used in the | |
396 | ;; argument list redefinition given in a piece of advice. While this simple | |
397 | ;; method might be sufficient in many cases, it has the disadvantage that it | |
398 | ;; is not very portable because it hardcodes the argument names into the | |
399 | ;; advice. If the definition of the original function changes the advice | |
400 | ;; might break even though the code might still be correct. Situations like | |
401 | ;; that arise, for example, if one advises a subr like `eval-region' which | |
402 | ;; gets redefined in a non-advice style into a function by the edebug | |
403 | ;; package. If the advice assumes `eval-region' to be a subr it might break | |
404 | ;; once edebug is loaded. Similar situations arise when one wants to use the | |
405 | ;; same piece of advice across different versions of Emacs. Some subrs in a | |
406 | ;; v18 Emacs are functions in v19 and vice versa, but for the most part the | |
407 | ;; semantics remain the same, hence, the same piece of advice might be usable | |
408 | ;; in both Emacs versions. | |
409 | ||
410 | ;; As a solution to that advice provides argument list access macros that get | |
411 | ;; translated into the proper access forms at activation time, i.e., when the | |
412 | ;; advised definition gets constructed. Access macros access actual arguments | |
413 | ;; by position regardless of how these actual argument get distributed onto | |
414 | ;; the argument variables of a function. The rational behind this is that in | |
415 | ;; Emacs Lisp the semantics of an argument is strictly determined by its | |
416 | ;; position (there are no keyword arguments). | |
417 | ||
418 | ;; Suppose the function `foo' is defined as | |
419 | ;; | |
420 | ;; (defun foo (x y &optional z &rest r) ....) | |
421 | ;; | |
422 | ;; and is then called with | |
423 | ;; | |
424 | ;; (foo 0 1 2 3 4 5 6) | |
425 | ||
426 | ;; which means that X=0, Y=1, Z=2 and R=(3 4 5 6). The assumption is that | |
427 | ;; the semantics of an actual argument is determined by its position. It is | |
428 | ;; this semantics that has to be known by the advice programmer. Then s/he | |
429 | ;; can access these arguments in a piece of advice with some of the | |
430 | ;; following macros (the arrows indicate what value they will return): | |
431 | ||
432 | ;; (ad-get-arg 0) -> 0 | |
433 | ;; (ad-get-arg 1) -> 1 | |
434 | ;; (ad-get-arg 2) -> 2 | |
435 | ;; (ad-get-arg 3) -> 3 | |
436 | ;; (ad-get-args 2) -> (2 3 4 5 6) | |
437 | ;; (ad-get-args 4) -> (4 5 6) | |
438 | ||
439 | ;; `(ad-get-arg <position>)' will return the actual argument that was supplied | |
440 | ;; at <position>, `(ad-get-args <position>)' will return the list of actual | |
441 | ;; arguments supplied starting at <position>. Note that these macros can be | |
442 | ;; used without any knowledge about the form of the actual argument list of | |
443 | ;; the original function. | |
444 | ||
445 | ;; Similarly, `(ad-set-arg <position> <value-form>)' can be used to set the | |
446 | ;; value of the actual argument at <position> to <value-form>. For example, | |
447 | ;; | |
448 | ;; (ad-set-arg 5 "five") | |
449 | ;; | |
450 | ;; will have the effect that R=(3 4 "five" 6) once the original function is | |
451 | ;; called. `(ad-set-args <position> <value-list-form>)' can be used to set | |
452 | ;; the list of actual arguments starting at <position> to <value-list-form>. | |
453 | ;; For example, | |
454 | ;; | |
455 | ;; (ad-set-args 0 '(5 4 3 2 1 0)) | |
456 | ;; | |
457 | ;; will have the effect that X=5, Y=4, Z=3 and R=(2 1 0) once the original | |
458 | ;; function is called. | |
459 | ||
460 | ;; All these access macros are text macros rather than real Lisp macros. When | |
461 | ;; the advised definition gets constructed they get replaced with actual access | |
462 | ;; forms depending on the argument list of the advised function, i.e., after | |
463 | ;; that argument access is in most cases as efficient as using the argument | |
464 | ;; variable names directly. | |
465 | ||
466 | ;; @@@ Accessing argument bindings of arbitrary functions: | |
467 | ;; ======================================================= | |
468 | ;; Some functions (such as `trace-function' defined in trace.el) need a | |
469 | ;; method of accessing the names and bindings of the arguments of an | |
470 | ;; arbitrary advised function. To do that within an advice one can use the | |
471 | ;; special keyword `ad-arg-bindings' which is a text macro that will be | |
472 | ;; substituted with a form that will evaluate to a list of binding | |
473 | ;; specifications, one for every argument variable. These binding | |
474 | ;; specifications can then be examined in the body of the advice. For | |
475 | ;; example, somewhere in an advice we could do this: | |
476 | ;; | |
477 | ;; (let* ((bindings ad-arg-bindings) | |
478 | ;; (firstarg (car bindings)) | |
479 | ;; (secondarg (car (cdr bindings)))) | |
480 | ;; ;; Print info about first argument | |
481 | ;; (print (format "%s=%s (%s)" | |
482 | ;; (ad-arg-binding-field firstarg 'name) | |
483 | ;; (ad-arg-binding-field firstarg 'value) | |
484 | ;; (ad-arg-binding-field firstarg 'type))) | |
485 | ;; ....) | |
486 | ;; | |
487 | ;; The `type' of an argument is either `required', `optional' or `rest'. | |
488 | ;; Wherever `ad-arg-bindings' appears a form will be inserted that evaluates | |
489 | ;; to the list of bindings, hence, in order to avoid multiple unnecessary | |
490 | ;; evaluations one should always bind it to some variable. | |
491 | ||
492 | ;; @@@ Argument list mapping: | |
493 | ;; ========================== | |
494 | ;; Because `defadvice' allows the specification of the argument list of the | |
495 | ;; advised function we need a mapping mechanism that maps this argument list | |
496 | ;; onto that of the original function. For example, somebody might specify | |
497 | ;; `(sym newdef)' as the argument list of `fset', while advice might use | |
498 | ;; `(&rest ad-subr-args)' as the argument list of the original function | |
499 | ;; (depending on what Emacs version is used). Hence SYM and NEWDEF have to | |
500 | ;; be properly mapped onto the &rest variable when the original definition is | |
501 | ;; called. Advice automatically takes care of that mapping, hence, the advice | |
502 | ;; programmer can specify an argument list without having to know about the | |
503 | ;; exact structure of the original argument list as long as the new argument | |
504 | ;; list takes a compatible number/magnitude of actual arguments. | |
505 | ||
506 | ;; @@@ Definition of subr argument lists: | |
507 | ;; ====================================== | |
508 | ;; When advice constructs the advised definition of a function it has to | |
509 | ;; know the argument list of the original function. For functions and macros | |
510 | ;; the argument list can be determined from the actual definition, however, | |
511 | ;; for subrs there is no such direct access available. In Lemacs and for some | |
6e2f6f45 | 512 | ;; subrs in Emacs-19 the argument list of a subr can be determined from |
ee7bf2ad RM |
513 | ;; its documentation string, in a v18 Emacs even that is not possible. If |
514 | ;; advice cannot at all determine the argument list of a subr it uses | |
515 | ;; `(&rest ad-subr-args)' which will always work but is inefficient because | |
516 | ;; it conses up arguments. The macro `ad-define-subr-args' can be used by | |
517 | ;; the advice programmer to explicitly tell advice about the argument list | |
518 | ;; of a certain subr, for example, | |
519 | ;; | |
520 | ;; (ad-define-subr-args 'fset '(sym newdef)) | |
521 | ;; | |
522 | ;; is used by advice itself to tell a v18 Emacs about the arguments of `fset'. | |
523 | ;; The following can be used to undo such a definition: | |
524 | ;; | |
525 | ;; (ad-undefine-subr-args 'fset) | |
526 | ;; | |
527 | ;; The argument list definition is stored on the property list of the subr | |
528 | ;; name symbol. When an argument list could be determined from the | |
529 | ;; documentation string it will be cached under that property. The general | |
530 | ;; mechanism for looking up the argument list of a subr is the following: | |
531 | ;; 1) look for a definition stored on the property list | |
532 | ;; 2) if that failed try to infer it from the documentation string and | |
533 | ;; if successful cache it on the property list | |
534 | ;; 3) otherwise use `(&rest ad-subr-args)' | |
535 | ||
536 | ;; @@ Activation and deactivation: | |
537 | ;; =============================== | |
538 | ;; The definition of an advised function does not change until all its advice | |
539 | ;; gets actually activated. Activation can either happen with the `activate' | |
540 | ;; flag specified in the `defadvice', with an explicit call or interactive | |
541 | ;; invocation of `ad-activate', or if forward advice is enabled (i.e., the | |
542 | ;; value of `ad-activate-on-definition' is t) at the time an already advised | |
543 | ;; function gets defined. | |
544 | ||
545 | ;; When a function gets first activated its original definition gets saved, | |
546 | ;; all defined and enabled pieces of advice will get combined with the | |
547 | ;; original definition, the resulting definition might get compiled depending | |
548 | ;; on some conditions described below, and then the function will get | |
549 | ;; redefined with the advised definition. This also means that undefined | |
550 | ;; functions cannot get activated even though they might be already advised. | |
551 | ||
552 | ;; The advised definition will get compiled either if `ad-activate' was called | |
553 | ;; interactively with a prefix argument, or called explicitly with its second | |
fabaa9b5 RS |
554 | ;; argument as t, or, if `ad-default-compilation-action' justifies it according |
555 | ;; to the current system state. If the advised definition was | |
ee7bf2ad RM |
556 | ;; constructed during "preactivation" (see below) then that definition will |
557 | ;; be already compiled because it was constructed during byte-compilation of | |
558 | ;; the file that contained the `defadvice' with the `preactivate' flag. | |
559 | ||
560 | ;; `ad-deactivate' can be used to back-define an advised function to its | |
561 | ;; original definition. It can be called interactively or directly. Because | |
562 | ;; `ad-activate' caches the advised definition the function can be | |
563 | ;; reactivated via `ad-activate' with only minor overhead (it is checked | |
564 | ;; whether the current advice state is consistent with the cached | |
565 | ;; definition, see the section on caching below). | |
566 | ||
567 | ;; `ad-activate-regexp' and `ad-deactivate-regexp' can be used to de/activate | |
568 | ;; all currently advised function that have a piece of advice with a name that | |
569 | ;; contains a match for a regular expression. These functions can be used to | |
570 | ;; de/activate sets of functions depending on certain advice naming | |
571 | ;; conventions. | |
572 | ||
573 | ;; Finally, `ad-activate-all' and `ad-deactivate-all' can be used to | |
574 | ;; de/activate all currently advised functions. These are useful to | |
575 | ;; (temporarily) return to an un/advised state. | |
576 | ||
577 | ;; @@@ Reasons for the separation of advice definition and activation: | |
578 | ;; =================================================================== | |
579 | ;; As already mentioned, advising happens in two stages: | |
580 | ||
581 | ;; 1) definition of various pieces of advice | |
582 | ;; 2) activation of all advice currently defined and enabled | |
583 | ||
584 | ;; The advantage of this is that various pieces of advice can be defined | |
585 | ;; before they get combined into an advised definition which avoids | |
586 | ;; unnecessary constructions of intermediate advised definitions. The more | |
587 | ;; important advantage is that it allows the implementation of forward advice. | |
588 | ;; Advice information for a certain function accumulates as the value of the | |
589 | ;; `advice-info' property of the function symbol. This accumulation is | |
590 | ;; completely independent of the fact that that function might not yet be | |
591 | ;; defined. The special forms `defun' and `defmacro' have been advised to | |
592 | ;; check whether the function/macro they defined had advice information | |
593 | ;; associated with it. If so and forward advice is enabled, the original | |
594 | ;; definition will be saved, and then the advice will be activated. When a | |
595 | ;; file is loaded in a v18 Emacs the functions/macros it defines are also | |
596 | ;; defined with calls to `defun/defmacro'. Hence, we can forward advise | |
597 | ;; functions/macros which will be defined later during a load/autoload of some | |
598 | ;; file (for compiled files generated by jwz's byte-compiler in a v19 Emacs | |
599 | ;; this is slightly more complicated but the basic idea is the same). | |
600 | ||
601 | ;; @@ Enabling/disabling pieces or sets of advice: | |
602 | ;; =============================================== | |
603 | ;; A major motivation for the development of this advice package was to bring | |
604 | ;; a little bit more structure into the function overloading chaos in Emacs | |
605 | ;; Lisp. Many packages achieve some of their functionality by adding a little | |
606 | ;; bit (or a lot) to the standard functionality of some Emacs Lisp function. | |
607 | ;; ange-ftp is a very popular package that achieves its magic by overloading | |
608 | ;; most Emacs Lisp functions that deal with files. A popular function that's | |
609 | ;; overloaded by many packages is `expand-file-name'. The situation that one | |
610 | ;; function is multiply overloaded can arise easily. | |
611 | ||
612 | ;; Once in a while it would be desirable to be able to disable some/all | |
613 | ;; overloads of a particular package while keeping all the rest. Ideally - | |
614 | ;; at least in my opinion - these overloads would all be done with advice, | |
615 | ;; I know I am dreaming right now... In that ideal case the enable/disable | |
616 | ;; mechanism of advice could be used to achieve just that. | |
617 | ||
618 | ;; Every piece of advice is associated with an enablement flag. When the | |
619 | ;; advised definition of a particular function gets constructed (e.g., during | |
620 | ;; activation) only the currently enabled pieces of advice will be considered. | |
621 | ;; This mechanism allows one to have different "views" of an advised function | |
622 | ;; dependent on what pieces of advice are currently enabled. | |
623 | ||
624 | ;; Another motivation for this mechanism is that it allows one to define a | |
625 | ;; piece of advice for some function yet keep it dormant until a certain | |
626 | ;; condition is met. Until then activation of the function will not make use | |
627 | ;; of that piece of advice. Once the condition is met the advice can be | |
628 | ;; enabled and a reactivation of the function will add its functionality as | |
629 | ;; part of the new advised definition. For example, the advices of `defun' | |
630 | ;; etc. used by advice itself will stay disabled until `ad-start-advice' is | |
631 | ;; called and some variables have the proper values. Hence, if somebody | |
632 | ;; else advised these functions too and activates them the advices defined | |
633 | ;; by advice will get used only if they are intended to be used. | |
634 | ||
635 | ;; The main interface to this mechanism are the interactive functions | |
636 | ;; `ad-enable-advice' and `ad-disable-advice'. For example, the following | |
637 | ;; would disable a particular advice of the function `foo': | |
638 | ;; | |
639 | ;; (ad-disable-advice 'foo 'before 'my-advice) | |
640 | ;; | |
641 | ;; This call by itself only changes the flag, to get the proper effect in | |
642 | ;; the advised definition too one has to activate `foo' with | |
643 | ;; | |
644 | ;; (ad-activate 'foo) | |
645 | ;; | |
646 | ;; or interactively. To disable whole sets of advices one can use a regular | |
647 | ;; expression mechanism. For example, let us assume that ange-ftp actually | |
648 | ;; used advice to overload all its functions, and that it used the | |
649 | ;; "ange-ftp-" prefix for all its advice names, then we could temporarily | |
650 | ;; disable all its advices with | |
651 | ;; | |
652 | ;; (ad-disable-regexp "^ange-ftp-") | |
653 | ;; | |
654 | ;; and the following call would put that actually into effect: | |
655 | ;; | |
656 | ;; (ad-activate-regexp "^ange-ftp-") | |
657 | ;; | |
658 | ;; A saver way would have been to use | |
659 | ;; | |
660 | ;; (ad-update-regexp "^ange-ftp-") | |
661 | ;; | |
662 | ;; instead which would have only reactivated currently actively advised | |
663 | ;; functions, but not functions that were currently deactivated. All these | |
664 | ;; functions can also be called interactively. | |
665 | ||
666 | ;; A certain piece of advice is considered a match if its name contains a | |
667 | ;; match for the regular expression. To enable ange-ftp again we would use | |
668 | ;; `ad-enable-regexp' and then activate or update again. | |
669 | ||
fabaa9b5 RS |
670 | ;; @@ Forward advice, automatic advice activation: |
671 | ;; =============================================== | |
ee7bf2ad RM |
672 | ;; Because most Emacs Lisp packages are loaded on demand via an autoload |
673 | ;; mechanism it is essential to be able to "forward advise" functions. | |
674 | ;; Otherwise, proper advice definition and activation would make it necessary | |
675 | ;; to preload every file that defines a certain function before it can be | |
676 | ;; advised, which would partly defeat the purpose of the advice mechanism. | |
677 | ||
678 | ;; In the following, "forward advice" always implies its automatic activation | |
679 | ;; once a function gets defined, and not just the accumulation of advice | |
680 | ;; information for a possibly undefined function. | |
681 | ||
682 | ;; Advice implements forward advice mainly via the following: 1) Separation | |
683 | ;; of advice definition and activation that makes it possible to accumulate | |
684 | ;; advice information without having the original function already defined, | |
fabaa9b5 RS |
685 | ;; 2) special versions of the built-in functions `fset/defalias' which check |
686 | ;; for advice information whenever they define a function. If advice | |
687 | ;; information was found then the advice will immediately get activated when | |
688 | ;; the function gets defined. | |
ee7bf2ad | 689 | |
fabaa9b5 | 690 | ;; Automatic advice activation means, that whenever a function gets defined |
ee7bf2ad RM |
691 | ;; with either `defun', `defmacro', `fset' or by loading a byte-compiled |
692 | ;; file, and the function has some advice-info stored with it then that | |
693 | ;; advice will get activated right away. | |
694 | ||
fabaa9b5 RS |
695 | ;; @@@ Enabling automatic advice activation: |
696 | ;; ========================================= | |
697 | ;; Automatic advice activation is enabled by default. It can be disabled by | |
698 | ;; doint `M-x ad-stop-advice' and enabled again with `M-x ad-start-advice'. | |
ee7bf2ad RM |
699 | |
700 | ;; @@ Caching of advised definitions: | |
701 | ;; ================================== | |
702 | ;; After an advised definition got constructed it gets cached as part of the | |
703 | ;; advised function's advice-info so it can be reused, for example, after an | |
704 | ;; intermediate deactivation. Because the advice-info of a function might | |
705 | ;; change between the time of caching and reuse a cached definition gets | |
706 | ;; a cache-id associated with it so it can be verified whether the cached | |
707 | ;; definition is still valid (the main application of this is preactivation | |
708 | ;; - see below). | |
709 | ||
710 | ;; When an advised function gets activated and a verifiable cached definition | |
711 | ;; is available, then that definition will be used instead of creating a new | |
712 | ;; advised definition from scratch. If you want to make sure that a new | |
713 | ;; definition gets constructed then you should use `ad-clear-cache' before you | |
714 | ;; activate the advised function. | |
715 | ||
716 | ;; @@ Preactivation: | |
717 | ;; ================= | |
718 | ;; Constructing an advised definition is moderately expensive. In a situation | |
719 | ;; where one package defines a lot of advised functions it might be | |
720 | ;; prohibitively expensive to do all the advised definition construction at | |
721 | ;; runtime. Preactivation is a mechanism that allows compile-time construction | |
722 | ;; of compiled advised definitions that can be activated cheaply during | |
723 | ;; runtime. Preactivation uses the caching mechanism to do that. Here's how it | |
724 | ;; works: | |
725 | ||
726 | ;; When the byte-compiler compiles a `defadvice' that has the `preactivate' | |
727 | ;; flag specified, it uses the current original definition of the advised | |
728 | ;; function plus the advice specified in this `defadvice' (even if it is | |
729 | ;; specified as disabled) and all other currently enabled pieces of advice to | |
730 | ;; construct an advised definition and an identifying cache-id and makes them | |
731 | ;; part of the `defadvice' expansion which will then be compiled by the | |
732 | ;; byte-compiler (to ensure that in a v18 emacs you have to put the | |
733 | ;; `defadvice' inside a `defun' to get it compiled and then you have to call | |
734 | ;; that compiled `defun' in order to actually execute the `defadvice'). When | |
735 | ;; the file with the compiled, preactivating `defadvice' gets loaded the | |
736 | ;; precompiled advised definition will be cached on the advised function's | |
737 | ;; advice-info. When it gets activated (can be immediately on execution of the | |
738 | ;; `defadvice' or any time later) the cache-id gets checked against the | |
739 | ;; current state of advice and if it is verified the precompiled definition | |
740 | ;; will be used directly (the verification is pretty cheap). If it couldn't get | |
741 | ;; verified a new advised definition for that function will be built from | |
742 | ;; scratch, hence, the efficiency added by the preactivation mechanism does | |
743 | ;; not at all impair the flexibility of the advice mechanism. | |
744 | ||
745 | ;; MORAL: In order get all the efficiency out of preactivation the advice | |
746 | ;; state of an advised function at the time the file with the | |
747 | ;; preactivating `defadvice' gets byte-compiled should be exactly | |
748 | ;; the same as it will be when the advice of that function gets | |
749 | ;; actually activated. If it is not there is a high chance that the | |
750 | ;; cache-id will not match and hence a new advised definition will | |
751 | ;; have to be constructed at runtime. | |
752 | ||
753 | ;; Preactivation and forward advice do not contradict each other. It is | |
754 | ;; perfectly ok to load a file with a preactivating `defadvice' before the | |
755 | ;; original definition of the advised function is available. The constructed | |
756 | ;; advised definition will be used once the original function gets defined and | |
757 | ;; its advice gets activated. The only constraint is that at the time the | |
758 | ;; file with the preactivating `defadvice' got compiled the original function | |
759 | ;; definition was available. | |
760 | ||
761 | ;; TIPS: Here are some indications that a preactivation did not work the way | |
762 | ;; you intended it to work: | |
763 | ;; - Activation of the advised function takes longer than usual/expected | |
764 | ;; - The byte-compiler gets loaded while an advised function gets | |
765 | ;; activated | |
766 | ;; - `byte-compile' is part of the `features' variable even though you | |
767 | ;; did not use the byte-compiler | |
768 | ;; Right now advice does not provide an elegant way to find out whether | |
769 | ;; and why a preactivation failed. What you can do is to trace the | |
770 | ;; function `ad-cache-id-verification-code' (with the function | |
771 | ;; `trace-function-background' defined in my trace.el package) before | |
772 | ;; any of your advised functions get activated. After they got | |
773 | ;; activated check whether all calls to `ad-cache-id-verification-code' | |
774 | ;; returned `verified' as a result. Other values indicate why the | |
775 | ;; verification failed which should give you enough information to | |
776 | ;; fix your preactivation/compile/load/activation sequence. | |
777 | ||
778 | ;; IMPORTANT: There is one case (that I am aware of) that can make | |
779 | ;; preactivation fail, i.e., a preconstructed advised definition that does | |
780 | ;; NOT match the current state of advice gets used nevertheless. That case | |
781 | ;; arises if one package defines a certain piece of advice which gets used | |
782 | ;; during preactivation, and another package incompatibly redefines that | |
783 | ;; very advice (i.e., same function/class/name), and it is the second advice | |
784 | ;; that is available when the preconstructed definition gets activated, and | |
785 | ;; that was the only definition of that advice so far (`ad-add-advice' | |
786 | ;; catches advice redefinitions and clears the cache in such a case). | |
787 | ;; Catching that would make the cache verification too expensive. | |
788 | ||
789 | ;; MORAL-II: Redefining somebody else's advice is BAAAAD (to speak with | |
790 | ;; George Walker Bush), and why would you redefine your own advice anyway? | |
791 | ;; Advice is a mechanism to facilitate function redefinition, not advice | |
6e2f6f45 | 792 | ;; redefinition (wait until I write Meta-Advice :-). If you really have |
ee7bf2ad RM |
793 | ;; to undo somebody else's advice try to write a "neutralizing" advice. |
794 | ||
795 | ;; @@ Advising macros and special forms and other dangerous things: | |
796 | ;; ================================================================ | |
797 | ;; Look at the corresponding tutorial sections for more information on | |
798 | ;; these topics. Here it suffices to point out that the special treatment | |
799 | ;; of macros and special forms by the byte-compiler can lead to problems | |
800 | ;; when they get advised. Macros can create problems because they get | |
801 | ;; expanded at compile time, hence, they might not have all the necessary | |
802 | ;; runtime support and such advice cannot be de/activated or changed as | |
803 | ;; it is possible for functions. Special forms create problems because they | |
804 | ;; have to be advised "into" macros, i.e., an advised special form is a | |
805 | ;; implemented as a macro, hence, in most cases the byte-compiler will | |
806 | ;; not recognize it as a special form anymore which can lead to very strange | |
807 | ;; results. | |
808 | ;; | |
809 | ;; MORAL: - Only advise macros or special forms when you are absolutely sure | |
810 | ;; what you are doing. | |
811 | ;; - As a safety measure, always do `ad-deactivate-all' before you | |
812 | ;; byte-compile a file to make sure that even if some inconsiderate | |
813 | ;; person advised some special forms you'll get proper compilation | |
814 | ;; results. After compilation do `ad-activate-all' to get back to | |
815 | ;; the previous state. | |
816 | ||
817 | ;; @@ Adding a piece of advice with `ad-add-advice': | |
818 | ;; ================================================= | |
819 | ;; The non-interactive function `ad-add-advice' can be used to add a piece of | |
820 | ;; advice to some function without using `defadvice'. This is useful if advice | |
821 | ;; has to be added somewhere by a function (also look at `ad-make-advice'). | |
822 | ||
823 | ;; @@ Activation/deactivation advices, file load hooks: | |
824 | ;; ==================================================== | |
825 | ;; There are two special classes of advice called `activation' and | |
826 | ;; `deactivation'. The body forms of these advices are not included into the | |
827 | ;; advised definition of a function, rather they are assembled into a hook | |
828 | ;; form which will be evaluated whenever the advice-info of the advised | |
829 | ;; function gets activated or deactivated. One application of this mechanism | |
830 | ;; is to define file load hooks for files that do not provide such hooks | |
831 | ;; (v19s already come with a general file-load-hook mechanism, v18s don't). | |
832 | ;; For example, suppose you want to print a message whenever `file-x' gets | |
833 | ;; loaded, and suppose the last function defined in `file-x' is | |
834 | ;; `file-x-last-fn'. Then we can define the following advice: | |
835 | ;; | |
836 | ;; (defadvice file-x-last-fn (activation file-x-load-hook) | |
837 | ;; "Executed whenever file-x is loaded" | |
838 | ;; (if load-in-progress (message "Loaded file-x"))) | |
839 | ;; | |
840 | ;; This will constitute a forward advice for function `file-x-last-fn' which | |
841 | ;; will get activated when `file-x' is loaded (only if forward advice is | |
842 | ;; enabled of course). Because there are no "real" pieces of advice | |
843 | ;; available for it, its definition will not be changed, but the activation | |
844 | ;; advice will be run during its activation which is equivalent to having a | |
845 | ;; file load hook for `file-x'. | |
846 | ||
847 | ;; @@ Summary of main advice concepts: | |
848 | ;; =================================== | |
849 | ;; - Definition: | |
850 | ;; A piece of advice gets defined with `defadvice' and added to the | |
851 | ;; `advice-info' property of a function. | |
852 | ;; - Enablement: | |
853 | ;; Every piece of advice has an enablement flag associated with it. Only | |
854 | ;; enabled advices are considered during construction of an advised | |
855 | ;; definition. | |
856 | ;; - Activation: | |
857 | ;; Redefine an advised function with its advised definition. Constructs | |
858 | ;; an advised definition from scratch if no verifiable cached advised | |
859 | ;; definition is available and caches it. | |
860 | ;; - Deactivation: | |
861 | ;; Back-define an advised function to its original definition. | |
862 | ;; - Update: | |
863 | ;; Reactivate an advised function but only if its advice is currently | |
864 | ;; active. This can be used to bring all currently advised function up | |
865 | ;; to date with the current state of advice without also activating | |
866 | ;; currently deactivated functions. | |
867 | ;; - Caching: | |
868 | ;; Is the saving of an advised definition and an identifying cache-id so | |
869 | ;; it can be reused, for example, for activation after deactivation. | |
870 | ;; - Preactivation: | |
871 | ;; Is the construction of an advised definition according to the current | |
872 | ;; state of advice during byte-compilation of a file with a preactivating | |
873 | ;; `defadvice'. That advised definition can then rather cheaply be used | |
874 | ;; during activation without having to construct an advised definition | |
875 | ;; from scratch at runtime. | |
876 | ||
877 | ;; @@ Summary of interactive advice manipulation functions: | |
878 | ;; ======================================================== | |
879 | ;; The following interactive functions can be used to manipulate the state | |
880 | ;; of advised functions (all of them support completion on function names, | |
881 | ;; advice classes and advice names): | |
882 | ||
883 | ;; - ad-activate to activate the advice of a FUNCTION | |
884 | ;; - ad-deactivate to deactivate the advice of a FUNCTION | |
885 | ;; - ad-update to activate the advice of a FUNCTION unless it was not | |
886 | ;; yet activated or is currently deactivated. | |
887 | ;; - ad-unadvise deactivates a FUNCTION and removes all of its advice | |
888 | ;; information, hence, it cannot be activated again | |
889 | ;; - ad-recover tries to redefine a FUNCTION to its original definition and | |
890 | ;; discards all advice information (a low-level `ad-unadvise'). | |
891 | ;; Use only in emergencies. | |
892 | ||
893 | ;; - ad-remove-advice removes a particular piece of advice of a FUNCTION. | |
894 | ;; You still have to do call `ad-activate' or `ad-update' to | |
895 | ;; activate the new state of advice. | |
896 | ;; - ad-enable-advice enables a particular piece of advice of a FUNCTION. | |
897 | ;; - ad-disable-advice disables a particular piece of advice of a FUNCTION. | |
898 | ;; - ad-enable-regexp maps over all currently advised functions and enables | |
899 | ;; every advice whose name contains a match for a regular | |
900 | ;; expression. | |
901 | ;; - ad-disable-regexp disables matching advices. | |
902 | ||
903 | ;; - ad-activate-regexp activates all advised function with a matching advice | |
904 | ;; - ad-deactivate-regexp deactivates all advised function with matching advice | |
905 | ;; - ad-update-regexp updates all advised function with a matching advice | |
906 | ;; - ad-activate-all activates all advised functions | |
907 | ;; - ad-deactivate-all deactivates all advised functions | |
908 | ;; - ad-update-all updates all advised functions | |
909 | ;; - ad-unadvise-all unadvises all advised functions | |
910 | ;; - ad-recover-all recovers all advised functions | |
911 | ||
912 | ;; - ad-compile byte-compiles a function/macro if it is compilable. | |
913 | ||
914 | ;; @@ Summary of forms with special meanings when used within an advice: | |
915 | ;; ===================================================================== | |
916 | ;; ad-return-value name of the return value variable (get/settable) | |
917 | ;; ad-subr-args name of &rest argument variable used for advised | |
918 | ;; subrs whose actual argument list cannot be | |
919 | ;; determined (get/settable) | |
920 | ;; (ad-get-arg <pos>), (ad-get-args <pos>), | |
921 | ;; (ad-set-arg <pos> <value>), (ad-set-args <pos> <value-list>) | |
922 | ;; argument access text macros to get/set the values of | |
923 | ;; actual arguments at a certain position | |
924 | ;; ad-arg-bindings text macro that returns the actual names, values | |
925 | ;; and types of the arguments as a list of bindings. The | |
926 | ;; order of the bindings corresponds to the order of the | |
927 | ;; arguments. The individual fields of every binding (name, | |
928 | ;; value and type) can be accessed with the function | |
929 | ;; `ad-arg-binding-field' (see example above). | |
930 | ;; ad-do-it text macro that identifies the place where the original | |
931 | ;; or wrapped definition should go in an around advice | |
932 | ||
933 | ||
934 | ;; @ Foo games: An advice tutorial | |
935 | ;; =============================== | |
6e2f6f45 | 936 | ;; The following tutorial was created in Emacs 18.59. Left-justified |
ee7bf2ad RM |
937 | ;; s-expressions are input forms followed by one or more result forms. |
938 | ;; First we have to start the advice magic: | |
939 | ;; | |
940 | ;; (ad-start-advice) | |
941 | ;; nil | |
942 | ;; | |
943 | ;; We start by defining an innocent looking function `foo' that simply | |
944 | ;; adds 1 to its argument X: | |
945 | ;; | |
946 | ;; (defun foo (x) | |
947 | ;; "Add 1 to X." | |
948 | ;; (1+ x)) | |
949 | ;; foo | |
950 | ;; | |
951 | ;; (foo 3) | |
952 | ;; 4 | |
953 | ;; | |
954 | ;; @@ Defining a simple piece of advice: | |
955 | ;; ===================================== | |
956 | ;; Now let's define the first piece of advice for `foo'. To do that we | |
957 | ;; use the macro `defadvice' which takes a function name, a list of advice | |
958 | ;; specifiers and a list of body forms as arguments. The first element of | |
959 | ;; the advice specifiers is the class of the advice, the second is its name, | |
960 | ;; the third its position and the rest are some flags. The class of our | |
961 | ;; first advice is `before', its name is `fg-add2', its position among the | |
962 | ;; currently defined before advices (none so far) is `first', and the advice | |
963 | ;; will be `activate'ed immediately. Advice names are global symbols, hence, | |
964 | ;; the name space conventions used for function names should be applied. All | |
965 | ;; advice names in this tutorial will be prefixed with `fg' for `Foo Games' | |
966 | ;; (because everybody has the right to be inconsistent all the function names | |
967 | ;; used in this tutorial do NOT follow this convention). | |
968 | ;; | |
969 | ;; In the body of an advice we can refer to the argument variables of the | |
970 | ;; original function by name. Here we add 1 to X so the effect of calling | |
971 | ;; `foo' will be to actually add 2. All of the advice definitions below only | |
972 | ;; have one body form for simplicity, but there is no restriction to that | |
973 | ;; extent. Every piece of advice can have a documentation string which will | |
974 | ;; be combined with the documentation of the original function. | |
975 | ;; | |
976 | ;; (defadvice foo (before fg-add2 first activate) | |
977 | ;; "Add 2 to X." | |
978 | ;; (setq x (1+ x))) | |
979 | ;; foo | |
980 | ;; | |
981 | ;; (foo 3) | |
982 | ;; 5 | |
983 | ;; | |
984 | ;; @@ Specifying the position of an advice: | |
985 | ;; ======================================== | |
986 | ;; Now we define the second before advice which will cancel the effect of | |
987 | ;; the previous advice. This time we specify the position as 0 which is | |
988 | ;; equivalent to `first'. A number can be used to specify the zero-based | |
989 | ;; position of an advice among the list of advices in the same class. This | |
990 | ;; time we already have one before advice hence the position specification | |
991 | ;; actually has an effect. So, after the following definition the position | |
992 | ;; of the previous advice will be 1 even though we specified it with `first' | |
993 | ;; above, the reason for this is that the position argument is relative to | |
994 | ;; the currently defined pieces of advice which by now has changed. | |
995 | ;; | |
996 | ;; (defadvice foo (before fg-cancel-add2 0 activate) | |
997 | ;; "Again only add 1 to X." | |
998 | ;; (setq x (1- x))) | |
999 | ;; foo | |
1000 | ;; | |
1001 | ;; (foo 3) | |
1002 | ;; 4 | |
1003 | ;; | |
1004 | ;; @@ Redefining a piece of advice: | |
1005 | ;; ================================ | |
1006 | ;; Now we define an advice with the same class and same name but with a | |
1007 | ;; different position. Defining an advice in a class in which an advice with | |
1008 | ;; that name already exists is interpreted as a redefinition of that | |
1009 | ;; particular advice, in which case the position argument will be ignored | |
1010 | ;; and the previous position of the redefined piece of advice is used. | |
1011 | ;; Advice flags can be specified with non-ambiguous initial substrings, hence, | |
1012 | ;; from now on we'll use `act' instead of the verbose `activate'. | |
1013 | ;; | |
1014 | ;; (defadvice foo (before fg-cancel-add2 last act) | |
1015 | ;; "Again only add 1 to X." | |
1016 | ;; (setq x (1- x))) | |
1017 | ;; foo | |
1018 | ;; | |
1019 | ;; @@ Assembly of advised documentation: | |
1020 | ;; ===================================== | |
1021 | ;; The documentation strings of the various pieces of advice are assembled | |
1022 | ;; in order which shows that advice `fg-cancel-add2' is still the first | |
1023 | ;; `before' advice even though we specified position `last' above: | |
1024 | ;; | |
1025 | ;; (documentation 'foo) | |
1026 | ;; "Add 1 to X. | |
1027 | ;; | |
1028 | ;; This function is advised with the following advice(s): | |
1029 | ;; | |
1030 | ;; fg-cancel-add2 (before): | |
1031 | ;; Again only add 1 to X. | |
1032 | ;; | |
1033 | ;; fg-add2 (before): | |
1034 | ;; Add 2 to X." | |
1035 | ;; | |
1036 | ;; @@ Advising interactive behavior: | |
1037 | ;; ================================= | |
1038 | ;; We can make a function interactive (or change its interactive behavior) | |
1039 | ;; by specifying an interactive form in one of the before or around | |
1040 | ;; advices (there could also be body forms in this advice). The particular | |
1041 | ;; definition always assigns 5 as an argument to X which gives us 6 as a | |
1042 | ;; result when we call foo interactively: | |
1043 | ;; | |
1044 | ;; (defadvice foo (before fg-inter last act) | |
1045 | ;; "Use 5 as argument when called interactively." | |
1046 | ;; (interactive (list 5))) | |
1047 | ;; foo | |
1048 | ;; | |
1049 | ;; (call-interactively 'foo) | |
1050 | ;; 6 | |
1051 | ;; | |
1052 | ;; If more than one advice have an interactive declaration, then the one of | |
1053 | ;; the advice with the smallest position will be used (before advices go | |
1054 | ;; before around and after advices), hence, the declaration below does | |
1055 | ;; not have any effect: | |
1056 | ;; | |
1057 | ;; (defadvice foo (before fg-inter2 last act) | |
1058 | ;; (interactive (list 6))) | |
1059 | ;; foo | |
1060 | ;; | |
1061 | ;; (call-interactively 'foo) | |
1062 | ;; 6 | |
1063 | ;; | |
1064 | ;; Let's have a look at what the definition of `foo' looks like now | |
1065 | ;; (indentation added by hand for legibility): | |
1066 | ;; | |
1067 | ;; (symbol-function 'foo) | |
1068 | ;; (lambda (x) | |
1069 | ;; "$ad-doc: foo$" | |
1070 | ;; (interactive (list 5)) | |
1071 | ;; (let (ad-return-value) | |
1072 | ;; (setq x (1- x)) | |
1073 | ;; (setq x (1+ x)) | |
1074 | ;; (setq ad-return-value (ad-Orig-foo x)) | |
1075 | ;; ad-return-value)) | |
1076 | ;; | |
1077 | ;; @@ Around advices: | |
1078 | ;; ================== | |
1079 | ;; Now we'll try some `around' advices. An around advice is a wrapper around | |
1080 | ;; the original definition. It can shadow or establish bindings for the | |
1081 | ;; original definition, and it can look at and manipulate the value returned | |
1082 | ;; by the original function. The position of the special keyword `ad-do-it' | |
1083 | ;; specifies where the code of the original function will be executed. The | |
1084 | ;; keyword can appear multiple times which will result in multiple calls of | |
1085 | ;; the original function in the resulting advised code. Note, that if we don't | |
1086 | ;; specify a position argument (i.e., `first', `last' or a number), then | |
1087 | ;; `first' (or 0) is the default): | |
1088 | ;; | |
1089 | ;; (defadvice foo (around fg-times-2 act) | |
1090 | ;; "First double X." | |
1091 | ;; (let ((x (* x 2))) | |
1092 | ;; ad-do-it)) | |
1093 | ;; foo | |
1094 | ;; | |
1095 | ;; (foo 3) | |
1096 | ;; 7 | |
1097 | ;; | |
1098 | ;; Around advices are assembled like onion skins where the around advice | |
1099 | ;; with position 0 is the outermost skin and the advice at the last position | |
1100 | ;; is the innermost skin which is directly wrapped around the call of the | |
1101 | ;; original definition of the function. Hence, after the next `defadvice' we | |
1102 | ;; will first multiply X by 2 then add 1 and then call the original | |
1103 | ;; definition (i.e., add 1 again): | |
1104 | ;; | |
1105 | ;; (defadvice foo (around fg-add-1 last act) | |
1106 | ;; "Add 1 to X." | |
1107 | ;; (let ((x (1+ x))) | |
1108 | ;; ad-do-it)) | |
1109 | ;; foo | |
1110 | ;; | |
1111 | ;; (foo 3) | |
1112 | ;; 8 | |
1113 | ;; | |
1114 | ;; Again, let's see what the definition of `foo' looks like so far: | |
1115 | ;; | |
1116 | ;; (symbol-function 'foo) | |
1117 | ;; (lambda (x) | |
1118 | ;; "$ad-doc: foo$" | |
1119 | ;; (interactive (list 5)) | |
1120 | ;; (let (ad-return-value) | |
1121 | ;; (setq x (1- x)) | |
1122 | ;; (setq x (1+ x)) | |
1123 | ;; (let ((x (* x 2))) | |
1124 | ;; (let ((x (1+ x))) | |
1125 | ;; (setq ad-return-value (ad-Orig-foo x)))) | |
1126 | ;; ad-return-value)) | |
1127 | ;; | |
1128 | ;; @@ Controlling advice activation: | |
1129 | ;; ================================= | |
1130 | ;; In every `defadvice' so far we have used the flag `activate' to activate | |
1131 | ;; the advice immediately after its definition, and that's what we want in | |
1132 | ;; most cases. However, if we define multiple pieces of advice for a single | |
1133 | ;; function then activating every advice immediately is inefficient. A | |
1134 | ;; better way to do this is to only activate the last defined advice. | |
1135 | ;; For example: | |
1136 | ;; | |
1137 | ;; (defadvice foo (after fg-times-x) | |
1138 | ;; "Multiply the result with X." | |
1139 | ;; (setq ad-return-value (* ad-return-value x))) | |
1140 | ;; foo | |
1141 | ;; | |
1142 | ;; This still yields the same result as before: | |
1143 | ;; (foo 3) | |
1144 | ;; 8 | |
1145 | ;; | |
1146 | ;; Now we define another advice and activate which will also activate the | |
1147 | ;; previous advice `fg-times-x'. Note the use of the special variable | |
1148 | ;; `ad-return-value' in the body of the advice which is set to the result of | |
1149 | ;; the original function. If we change its value then the value returned by | |
1150 | ;; the advised function will be changed accordingly: | |
1151 | ;; | |
1152 | ;; (defadvice foo (after fg-times-x-again act) | |
1153 | ;; "Again multiply the result with X." | |
1154 | ;; (setq ad-return-value (* ad-return-value x))) | |
1155 | ;; foo | |
1156 | ;; | |
1157 | ;; Now the advices have an effect: | |
1158 | ;; | |
1159 | ;; (foo 3) | |
1160 | ;; 72 | |
1161 | ;; | |
1162 | ;; @@ Protecting advice execution: | |
1163 | ;; =============================== | |
1164 | ;; Once in a while we define an advice to perform some cleanup action, | |
1165 | ;; for example: | |
1166 | ;; | |
1167 | ;; (defadvice foo (after fg-cleanup last act) | |
1168 | ;; "Do some cleanup." | |
1169 | ;; (print "Let's clean up now!")) | |
1170 | ;; foo | |
1171 | ;; | |
1172 | ;; However, in case of an error the cleanup won't be performed: | |
1173 | ;; | |
1174 | ;; (condition-case error | |
1175 | ;; (foo t) | |
1176 | ;; (error 'error-in-foo)) | |
1177 | ;; error-in-foo | |
1178 | ;; | |
1179 | ;; To make sure a certain piece of advice gets executed even if some error or | |
1180 | ;; non-local exit occurred in any preceding code, we can protect it by using | |
1181 | ;; the `protect' keyword. (if any of the around advices is protected then the | |
1182 | ;; whole around advice onion will be protected): | |
1183 | ;; | |
1184 | ;; (defadvice foo (after fg-cleanup prot act) | |
1185 | ;; "Do some protected cleanup." | |
1186 | ;; (print "Let's clean up now!")) | |
1187 | ;; foo | |
1188 | ;; | |
1189 | ;; Now the cleanup form will be executed even in case of an error: | |
1190 | ;; | |
1191 | ;; (condition-case error | |
1192 | ;; (foo t) | |
1193 | ;; (error 'error-in-foo)) | |
1194 | ;; "Let's clean up now!" | |
1195 | ;; error-in-foo | |
1196 | ;; | |
1197 | ;; Again, let's see what `foo' looks like: | |
1198 | ;; | |
1199 | ;; (symbol-function 'foo) | |
1200 | ;; (lambda (x) | |
1201 | ;; "$ad-doc: foo$" | |
1202 | ;; (interactive (list 5)) | |
1203 | ;; (let (ad-return-value) | |
1204 | ;; (unwind-protect | |
1205 | ;; (progn (setq x (1- x)) | |
1206 | ;; (setq x (1+ x)) | |
1207 | ;; (let ((x (* x 2))) | |
1208 | ;; (let ((x (1+ x))) | |
1209 | ;; (setq ad-return-value (ad-Orig-foo x)))) | |
1210 | ;; (setq ad-return-value (* ad-return-value x)) | |
1211 | ;; (setq ad-return-value (* ad-return-value x))) | |
1212 | ;; (print "Let's clean up now!")) | |
1213 | ;; ad-return-value)) | |
1214 | ;; | |
1215 | ;; @@ Compilation of advised definitions: | |
1216 | ;; ====================================== | |
1217 | ;; Finally, we can specify the `compile' keyword in a `defadvice' to say | |
1218 | ;; that we want the resulting advised function to be byte-compiled | |
1219 | ;; (`compile' will be ignored unless we also specified `activate'): | |
1220 | ;; | |
1221 | ;; (defadvice foo (after fg-cleanup prot act comp) | |
1222 | ;; "Do some protected cleanup." | |
1223 | ;; (print "Let's clean up now!")) | |
1224 | ;; foo | |
1225 | ;; | |
1226 | ;; Now `foo' is byte-compiled: | |
1227 | ;; | |
1228 | ;; (symbol-function 'foo) | |
1229 | ;; (lambda (x) | |
1230 | ;; "$ad-doc: foo$" | |
1231 | ;; (interactive (byte-code "....." [5] 1)) | |
1232 | ;; (byte-code "....." [ad-return-value x nil ((byte-code "....." [print "Let's clean up now!"] 2)) * 2 ad-Orig-foo] 6)) | |
1233 | ;; | |
1234 | ;; (foo 3) | |
1235 | ;; "Let's clean up now!" | |
1236 | ;; 72 | |
1237 | ;; | |
1238 | ;; @@ Enabling and disabling pieces of advice: | |
1239 | ;; =========================================== | |
1240 | ;; Once in a while it is desirable to temporarily disable a piece of advice | |
1241 | ;; so that it won't be considered during activation, for example, if two | |
1242 | ;; different packages advise the same function and one wants to temporarily | |
1243 | ;; neutralize the effect of the advice of one of the packages. | |
1244 | ;; | |
1245 | ;; The following disables the after advice `fg-times-x' in the function `foo'. | |
1246 | ;; All that does is to change a flag for this particular advice. All the | |
1247 | ;; other information defining it will be left unchanged (e.g., its relative | |
1248 | ;; position in this advice class, etc.). | |
1249 | ;; | |
1250 | ;; (ad-disable-advice 'foo 'after 'fg-times-x) | |
1251 | ;; nil | |
1252 | ;; | |
1253 | ;; For this to have an effect we have to activate `foo': | |
1254 | ;; | |
1255 | ;; (ad-activate 'foo) | |
1256 | ;; foo | |
1257 | ;; | |
1258 | ;; (foo 3) | |
1259 | ;; "Let's clean up now!" | |
1260 | ;; 24 | |
1261 | ;; | |
1262 | ;; If we want to disable all multiplication advices in `foo' we can use a | |
1263 | ;; regular expression that matches the names of such advices. Actually, any | |
1264 | ;; advice name that contains a match for the regular expression will be | |
1265 | ;; called a match. A special advice class `any' can be used to consider | |
1266 | ;; all advice classes: | |
1267 | ;; | |
1268 | ;; (ad-disable-advice 'foo 'any "^fg-.*times") | |
1269 | ;; nil | |
1270 | ;; | |
1271 | ;; (ad-activate 'foo) | |
1272 | ;; foo | |
1273 | ;; | |
1274 | ;; (foo 3) | |
1275 | ;; "Let's clean up now!" | |
1276 | ;; 5 | |
1277 | ;; | |
1278 | ;; To enable the disabled advice we could use either `ad-enable-advice' | |
1279 | ;; similar to `ad-disable-advice', or as an alternative `ad-enable-regexp' | |
1280 | ;; which will enable matching advices in ALL currently advised functions. | |
1281 | ;; Hence, this can be used to dis/enable advices made by a particular | |
1282 | ;; package to a set of functions as long as that package obeys standard | |
1283 | ;; advice name conventions. We prefixed all advice names with `fg-', hence | |
1284 | ;; the following will do the trick (`ad-enable-regexp' returns the number | |
1285 | ;; of matched advices): | |
1286 | ;; | |
1287 | ;; (ad-enable-regexp "^fg-") | |
1288 | ;; 9 | |
1289 | ;; | |
1290 | ;; The following will activate all currently active advised functions that | |
1291 | ;; contain some advice matched by the regular expression. This is a save | |
1292 | ;; way to update the activation of advised functions whose advice changed | |
1293 | ;; in some way or other without accidentally also activating currently | |
1294 | ;; deactivated functions: | |
1295 | ;; | |
1296 | ;; (ad-update-regexp "^fg-") | |
1297 | ;; nil | |
1298 | ;; | |
1299 | ;; (foo 3) | |
1300 | ;; "Let's clean up now!" | |
1301 | ;; 72 | |
1302 | ;; | |
1303 | ;; Another use for the dis/enablement mechanism is to define a piece of advice | |
1304 | ;; and keep it "dormant" until a particular condition is satisfied, i.e., until | |
1305 | ;; then the advice will not be used during activation. The `disable' flag lets | |
1306 | ;; one do that with `defadvice': | |
1307 | ;; | |
1308 | ;; (defadvice foo (before fg-1-more dis) | |
1309 | ;; "Add yet 1 more." | |
1310 | ;; (setq x (1+ x))) | |
1311 | ;; foo | |
1312 | ;; | |
1313 | ;; (ad-activate 'foo) | |
1314 | ;; foo | |
1315 | ;; | |
1316 | ;; (foo 3) | |
1317 | ;; "Let's clean up now!" | |
1318 | ;; 72 | |
1319 | ;; | |
1320 | ;; (ad-enable-advice 'foo 'before 'fg-1-more) | |
1321 | ;; nil | |
1322 | ;; | |
1323 | ;; (ad-activate 'foo) | |
1324 | ;; foo | |
1325 | ;; | |
1326 | ;; (foo 3) | |
1327 | ;; "Let's clean up now!" | |
1328 | ;; 160 | |
1329 | ;; | |
1330 | ;; @@ Caching: | |
1331 | ;; =========== | |
1332 | ;; Advised definitions get cached to allow efficient activation/deactivation | |
1333 | ;; without having to reconstruct them if nothing in the advice-info of a | |
1334 | ;; function has changed. The following idiom can be used to temporarily | |
1335 | ;; deactivate functions that have a piece of advice defined by a certain | |
1336 | ;; package (we save the old definition to check out caching): | |
1337 | ;; | |
1338 | ;; (setq old-definition (symbol-function 'foo)) | |
1339 | ;; (lambda (x) ....) | |
1340 | ;; | |
1341 | ;; (ad-deactivate-regexp "^fg-") | |
1342 | ;; nil | |
1343 | ;; | |
1344 | ;; (foo 3) | |
1345 | ;; 4 | |
1346 | ;; | |
1347 | ;; (ad-activate-regexp "^fg-") | |
1348 | ;; nil | |
1349 | ;; | |
1350 | ;; (eq old-definition (symbol-function 'foo)) | |
1351 | ;; t | |
1352 | ;; | |
1353 | ;; (foo 3) | |
1354 | ;; "Let's clean up now!" | |
1355 | ;; 160 | |
1356 | ;; | |
1357 | ;; @@ Forward advice: | |
1358 | ;; ================== | |
1359 | ;; To enable automatic activation of forward advice we first have to set | |
1360 | ;; `ad-activate-on-definition' to t and restart advice: | |
1361 | ;; | |
1362 | ;; (setq ad-activate-on-definition t) | |
1363 | ;; t | |
1364 | ;; | |
1365 | ;; (ad-start-advice) | |
1366 | ;; (ad-activate-defined-function) | |
1367 | ;; | |
1368 | ;; Let's define a piece of advice for an undefined function: | |
1369 | ;; | |
1370 | ;; (defadvice bar (before fg-sub-1-more act) | |
1371 | ;; "Subtract one more from X." | |
1372 | ;; (setq x (1- x))) | |
1373 | ;; bar | |
1374 | ;; | |
1375 | ;; `bar' is not yet defined: | |
1376 | ;; (fboundp 'bar) | |
1377 | ;; nil | |
1378 | ;; | |
1379 | ;; Now we define it and the forward advice will get activated (only because | |
1380 | ;; `ad-activate-on-definition' was t when we started advice above with | |
1381 | ;; `ad-start-advice'): | |
1382 | ;; | |
1383 | ;; (defun bar (x) | |
1384 | ;; "Subtract 1 from X." | |
1385 | ;; (1- x)) | |
1386 | ;; bar | |
1387 | ;; | |
1388 | ;; (bar 4) | |
1389 | ;; 2 | |
1390 | ;; | |
1391 | ;; Redefinition will activate any available advice if the value of | |
1392 | ;; `ad-redefinition-action' is either `warn', `accept' or `discard': | |
1393 | ;; | |
1394 | ;; (defun bar (x) | |
1395 | ;; "Subtract 2 from X." | |
1396 | ;; (- x 2)) | |
1397 | ;; bar | |
1398 | ;; | |
1399 | ;; (bar 4) | |
1400 | ;; 1 | |
1401 | ;; | |
1402 | ;; @@ Preactivation: | |
1403 | ;; ================= | |
1404 | ;; Constructing advised definitions is moderately expensive, hence, it is | |
1405 | ;; desirable to have a way to construct them at byte-compile time. | |
1406 | ;; Preactivation is a mechanism that allows one to do that. | |
1407 | ;; | |
1408 | ;; (defun fie (x) | |
1409 | ;; "Multiply X by 2." | |
1410 | ;; (* x 2)) | |
1411 | ;; fie | |
1412 | ;; | |
1413 | ;; (defadvice fie (before fg-times-4 preact) | |
1414 | ;; "Multiply X by 4." | |
1415 | ;; (setq x (* x 2))) | |
1416 | ;; fie | |
1417 | ;; | |
1418 | ;; This advice did not affect `fie'... | |
1419 | ;; | |
1420 | ;; (fie 2) | |
1421 | ;; 4 | |
1422 | ;; | |
1423 | ;; ...but it constructed a cached definition that will be used once `fie' gets | |
1424 | ;; activated as long as its current advice state is the same as it was during | |
1425 | ;; preactivation: | |
1426 | ;; | |
1427 | ;; (setq cached-definition (ad-get-cache-definition 'fie)) | |
1428 | ;; (lambda (x) ....) | |
1429 | ;; | |
1430 | ;; (ad-activate 'fie) | |
1431 | ;; fie | |
1432 | ;; | |
1433 | ;; (eq cached-definition (symbol-function 'fie)) | |
1434 | ;; t | |
1435 | ;; | |
1436 | ;; (fie 2) | |
1437 | ;; 8 | |
1438 | ;; | |
c0d79871 | 1439 | ;; If you put a preactivating `defadvice' into a Lisp file that gets byte- |
ee7bf2ad RM |
1440 | ;; compiled then the constructed advised definition will get compiled by |
1441 | ;; the byte-compiler. For that to occur in a v18 emacs you have to put the | |
1442 | ;; `defadvice' inside a `defun' because the v18 compiler does not compile | |
1443 | ;; top-level forms other than `defun' or `defmacro', for example, | |
1444 | ;; | |
1445 | ;; (defun fg-defadvice-fum () | |
1446 | ;; (defadvice fum (before fg-times-4 preact act) | |
1447 | ;; "Multiply X by 4." | |
1448 | ;; (setq x (* x 2)))) | |
1449 | ;; fg-defadvice-fum | |
1450 | ;; | |
1451 | ;; So far, no `defadvice' for `fum' got executed, but when we compile | |
1452 | ;; `fg-defadvice-fum' the `defadvice' will be expanded by the byte compiler. | |
1453 | ;; In order for preactivation to be effective we have to have a proper | |
1454 | ;; definition of `fum' around at preactivation time, hence, we define it now: | |
1455 | ;; | |
1456 | ;; (defun fum (x) | |
1457 | ;; "Multiply X by 2." | |
1458 | ;; (* x 2)) | |
1459 | ;; fum | |
1460 | ;; | |
1461 | ;; Now we compile the defining function which will construct an advised | |
1462 | ;; definition during expansion of the `defadvice', compile it and store it | |
1463 | ;; as part of the compiled `fg-defadvice-fum': | |
1464 | ;; | |
1465 | ;; (ad-compile-function 'fg-defadvice-fum) | |
1466 | ;; (lambda nil (byte-code ...)) | |
1467 | ;; | |
1468 | ;; `fum' is still completely unaffected: | |
1469 | ;; | |
1470 | ;; (fum 2) | |
1471 | ;; 4 | |
1472 | ;; | |
1473 | ;; (ad-get-advice-info 'fum) | |
1474 | ;; nil | |
1475 | ;; | |
1476 | ;; (fg-defadvice-fum) | |
1477 | ;; fum | |
1478 | ;; | |
1479 | ;; Now the advised version of `fum' is compiled because the compiled definition | |
1480 | ;; constructed during preactivation was used, even though we did not specify | |
1481 | ;; the `compile' flag: | |
1482 | ;; | |
1483 | ;; (symbol-function 'fum) | |
1484 | ;; (lambda (x) | |
1485 | ;; "$ad-doc: fum$" | |
1486 | ;; (byte-code "....." [ad-return-value x nil * 2 ad-Orig-fum] 4)) | |
1487 | ;; | |
1488 | ;; (fum 2) | |
1489 | ;; 8 | |
1490 | ;; | |
1491 | ;; A preactivated definition will only be used if it matches the current | |
1492 | ;; function definition and advice information. If it does not match it | |
1493 | ;; will simply be discarded and a new advised definition will be constructed | |
1494 | ;; from scratch. For example, let's first remove all advice-info for `fum': | |
1495 | ;; | |
1496 | ;; (ad-unadvise 'fum) | |
1497 | ;; (("fie") ("bar") ("foo") ...) | |
1498 | ;; | |
1499 | ;; And now define a new piece of advice: | |
1500 | ;; | |
1501 | ;; (defadvice fum (before fg-interactive act) | |
1502 | ;; "Make fum interactive." | |
1503 | ;; (interactive "nEnter x: ")) | |
1504 | ;; fum | |
1505 | ;; | |
1506 | ;; When we now try to use a preactivation it will not be used because the | |
1507 | ;; current advice state is different from the one at preactivation time. This | |
1508 | ;; is no tragedy, everything will work as expected just not as efficient, | |
1509 | ;; because a new advised definition has to be constructed from scratch: | |
1510 | ;; | |
1511 | ;; (fg-defadvice-fum) | |
1512 | ;; fum | |
1513 | ;; | |
1514 | ;; A new uncompiled advised definition got constructed: | |
1515 | ;; | |
1516 | ;; (ad-compiled-p (symbol-function 'fum)) | |
1517 | ;; nil | |
1518 | ;; | |
1519 | ;; (fum 2) | |
1520 | ;; 8 | |
1521 | ;; | |
1522 | ;; MORAL: To get all the efficiency out of preactivation the function | |
1523 | ;; definition and advice state at preactivation time must be the same as the | |
1524 | ;; state at activation time. Preactivation does work with forward advice, all | |
1525 | ;; that's necessary is that the definition of the forward advised function is | |
1526 | ;; available when the `defadvice' with the preactivation gets compiled. | |
1527 | ;; | |
1528 | ;; @@ Portable argument access: | |
1529 | ;; ============================ | |
1530 | ;; So far, we always used the actual argument variable names to access an | |
1531 | ;; argument in a piece of advice. For many advice applications this is | |
1532 | ;; perfectly ok and keeps advices simple. However, it decreases portability | |
1533 | ;; of advices because it assumes specific argument variable names. For example, | |
1534 | ;; if one advises a subr such as `eval-region' which then gets redefined by | |
1535 | ;; some package (e.g., edebug) into a function with different argument names, | |
1536 | ;; then a piece of advice written for `eval-region' that was written with | |
1537 | ;; the subr arguments in mind will break. Similar situations arise when one | |
1538 | ;; switches between major Emacs versions, e.g., certain subrs in v18 are | |
1539 | ;; functions in v19 and vice versa. Also, in v19s subr argument lists | |
1540 | ;; are available and will be used, while they are not available in v18. | |
1541 | ;; | |
1542 | ;; Argument access text macros allow one to access arguments of an advised | |
1543 | ;; function in a portable way without having to worry about all these | |
1544 | ;; possibilities. These macros will be translated into the proper access forms | |
1545 | ;; at activation time, hence, argument access will be as efficient as if | |
1546 | ;; the arguments had been used directly in the definition of the advice. | |
1547 | ;; | |
1548 | ;; (defun fuu (x y z) | |
1549 | ;; "Add 3 numbers." | |
1550 | ;; (+ x y z)) | |
1551 | ;; fuu | |
1552 | ;; | |
1553 | ;; (fuu 1 1 1) | |
1554 | ;; 3 | |
1555 | ;; | |
1556 | ;; Argument access macros specify actual arguments at a certain position. | |
1557 | ;; Position 0 access the first actual argument, position 1 the second etc. | |
1558 | ;; For example, the following advice adds 1 to each of the 3 arguments: | |
1559 | ;; | |
1560 | ;; (defadvice fuu (before fg-add-1-to-all act) | |
1561 | ;; "Adds 1 to all arguments." | |
1562 | ;; (ad-set-arg 0 (1+ (ad-get-arg 0))) | |
1563 | ;; (ad-set-arg 1 (1+ (ad-get-arg 1))) | |
1564 | ;; (ad-set-arg 2 (1+ (ad-get-arg 2)))) | |
1565 | ;; fuu | |
1566 | ;; | |
1567 | ;; (fuu 1 1 1) | |
1568 | ;; 6 | |
1569 | ;; | |
1570 | ;; Now suppose somebody redefines `fuu' with a rest argument. Our advice | |
1571 | ;; will still work because we used access macros (note, that automatic | |
1572 | ;; advice activation is still in effect, hence, the redefinition of `fuu' | |
1573 | ;; will automatically activate all its advice): | |
1574 | ;; | |
1575 | ;; (defun fuu (&rest numbers) | |
1576 | ;; "Add NUMBERS." | |
1577 | ;; (apply '+ numbers)) | |
1578 | ;; fuu | |
1579 | ;; | |
1580 | ;; (fuu 1 1 1) | |
1581 | ;; 6 | |
1582 | ;; | |
1583 | ;; (fuu 1 1 1 1 1 1) | |
1584 | ;; 9 | |
1585 | ;; | |
1586 | ;; What's important to notice is that argument access macros access actual | |
1587 | ;; arguments regardless of how they got distributed onto argument variables. | |
1588 | ;; In Emacs Lisp the semantics of an actual argument is determined purely | |
1589 | ;; by position, hence, as long as nobody changes the semantics of what a | |
1590 | ;; certain actual argument at a certain position means the access macros | |
1591 | ;; will do the right thing. | |
1592 | ;; | |
1593 | ;; Because of &rest arguments we need a second kind of access macro that | |
1594 | ;; can access all actual arguments starting from a certain position: | |
1595 | ;; | |
1596 | ;; (defadvice fuu (before fg-print-args act) | |
1597 | ;; "Print all arguments." | |
1598 | ;; (print (ad-get-args 0))) | |
1599 | ;; fuu | |
1600 | ;; | |
1601 | ;; (fuu 1 2 3 4 5) | |
1602 | ;; (1 2 3 4 5) | |
1603 | ;; 18 | |
1604 | ;; | |
1605 | ;; (defadvice fuu (before fg-set-args act) | |
1606 | ;; "Swaps 2nd and 3rd arg and discards all the rest." | |
1607 | ;; (ad-set-args 1 (list (ad-get-arg 2) (ad-get-arg 1)))) | |
1608 | ;; fuu | |
1609 | ;; | |
1610 | ;; (fuu 1 2 3 4 4 4 4 4 4) | |
1611 | ;; (1 3 2) | |
1612 | ;; 9 | |
1613 | ;; | |
1614 | ;; (defun fuu (x y z) | |
1615 | ;; "Add 3 numbers." | |
1616 | ;; (+ x y z)) | |
1617 | ;; | |
1618 | ;; (fuu 1 2 3) | |
1619 | ;; (1 3 2) | |
1620 | ;; 9 | |
1621 | ;; | |
1622 | ;; @@ Defining the argument list of an advised function: | |
1623 | ;; ===================================================== | |
1624 | ;; Once in a while it might be desirable to advise a function and additionally | |
1625 | ;; give it an extra argument that controls the advised code, for example, one | |
1626 | ;; might want to make an interactive function sensitive to a prefix argument. | |
1627 | ;; For such cases `defadvice' allows the specification of an argument list | |
1628 | ;; for the advised function. Similar to the redefinition of interactive | |
1629 | ;; behavior, the first argument list specification found in the list of before/ | |
1630 | ;; around/after advices will be used. Of course, the specified argument list | |
1631 | ;; should be downward compatible with the original argument list, otherwise | |
1632 | ;; functions that call the advised function with the original argument list | |
1633 | ;; in mind will break. | |
1634 | ;; | |
1635 | ;; (defun fii (x) | |
1636 | ;; "Add 1 to X." | |
1637 | ;; (1+ x)) | |
1638 | ;; fii | |
1639 | ;; | |
1640 | ;; Now we advise `fii' to use an optional second argument that controls the | |
1641 | ;; amount of incrementation. A list following the (optional) position | |
1642 | ;; argument of the advice will be interpreted as an argument list | |
1643 | ;; specification. This means you cannot specify an empty argument list, and | |
1644 | ;; why would you want to anyway? | |
1645 | ;; | |
1646 | ;; (defadvice fii (before fg-inc-x (x &optional incr) act) | |
1647 | ;; "Increment X by INCR (default is 1)." | |
1648 | ;; (setq x (+ x (1- (or incr 1))))) | |
1649 | ;; fii | |
1650 | ;; | |
1651 | ;; (fii 3) | |
1652 | ;; 4 | |
1653 | ;; | |
1654 | ;; (fii 3 2) | |
1655 | ;; 5 | |
1656 | ;; | |
1657 | ;; @@ Specifying argument lists of subrs: | |
1658 | ;; ====================================== | |
1659 | ;; The argument lists of subrs cannot be determined directly from Lisp. | |
6e2f6f45 | 1660 | ;; This means that Advice has to use `(&rest ad-subr-args)' as the |
ee7bf2ad RM |
1661 | ;; argument list of the advised subr which is not very efficient. In Lemacs |
1662 | ;; subr argument lists can be determined from their documentation string, in | |
6e2f6f45 | 1663 | ;; Emacs-19 this is the case for some but not all subrs. To accommodate |
ee7bf2ad | 1664 | ;; for the cases where the argument lists cannot be determined (e.g., in a |
6e2f6f45 | 1665 | ;; v18 Emacs) Advice comes with a specification mechanism that allows the |
ee7bf2ad RM |
1666 | ;; advice programmer to tell advice what the argument list of a certain subr |
1667 | ;; really is. | |
1668 | ;; | |
1669 | ;; In a v18 Emacs the following will return the &rest idiom: | |
1670 | ;; | |
1671 | ;; (ad-arglist (symbol-function 'car)) | |
1672 | ;; (&rest ad-subr-args) | |
1673 | ;; | |
1674 | ;; To tell advice what the argument list of `car' really is we | |
1675 | ;; can do the following: | |
1676 | ;; | |
1677 | ;; (ad-define-subr-args 'car '(list)) | |
1678 | ;; ((list)) | |
1679 | ;; | |
1680 | ;; Now `ad-arglist' will return the proper argument list (this method is | |
1681 | ;; actually used by advice itself for the advised definition of `fset'): | |
1682 | ;; | |
1683 | ;; (ad-arglist (symbol-function 'car)) | |
1684 | ;; (list) | |
1685 | ;; | |
1686 | ;; The defined argument list will be stored on the property list of the | |
1687 | ;; subr name symbol. When advice looks for a subr argument list it first | |
1688 | ;; checks for a definition on the property list, if that fails it tries | |
1689 | ;; to infer it from the documentation string and caches it on the property | |
1690 | ;; list if it was successful, otherwise `(&rest ad-subr-args)' will be used. | |
1691 | ;; | |
1692 | ;; @@ Advising interactive subrs: | |
1693 | ;; ============================== | |
1694 | ;; For the most part there is no difference between advising functions and | |
1695 | ;; advising subrs. There is one situation though where one might have to write | |
1696 | ;; slightly different advice code for subrs than for functions. This case | |
1697 | ;; arises when one wants to access subr arguments in a before/around advice | |
1698 | ;; when the arguments were determined by an interactive call to the subr. | |
1699 | ;; Advice cannot determine what `interactive' form determines the interactive | |
1700 | ;; behavior of the subr, hence, when it calls the original definition in an | |
1701 | ;; interactive subr invocation it has to use `call-interactively' to generate | |
1702 | ;; the proper interactive behavior. Thus up to that call the arguments of the | |
1703 | ;; interactive subr will be nil. For example, the following advice for | |
1704 | ;; `kill-buffer' will not work in an interactive invocation... | |
1705 | ;; | |
1706 | ;; (defadvice kill-buffer (before fg-kill-buffer-hook first act preact comp) | |
1707 | ;; (my-before-kill-buffer-hook (ad-get-arg 0))) | |
1708 | ;; kill-buffer | |
1709 | ;; | |
1710 | ;; ...because the buffer argument will be nil in that case. The way out of | |
1711 | ;; this dilemma is to provide an `interactive' specification that mirrors | |
1712 | ;; the interactive behavior of the unadvised subr, for example, the following | |
1713 | ;; will do the right thing even when `kill-buffer' is called interactively: | |
1714 | ;; | |
1715 | ;; (defadvice kill-buffer (before fg-kill-buffer-hook first act preact comp) | |
1716 | ;; (interactive "bKill buffer: ") | |
1717 | ;; (my-before-kill-buffer-hook (ad-get-arg 0))) | |
1718 | ;; kill-buffer | |
1719 | ;; | |
1720 | ;; @@ Advising macros: | |
1721 | ;; =================== | |
1722 | ;; Advising macros is slightly different because there are two significant | |
1723 | ;; time points in the invocation of a macro: Expansion and evaluation time. | |
1724 | ;; For an advised macro instead of evaluating the original definition we | |
1725 | ;; use `macroexpand', that is, changing argument values and binding | |
1726 | ;; environments by pieces of advice has an affect during macro expansion | |
1727 | ;; but not necessarily during evaluation. In particular, any side effects | |
1728 | ;; of pieces of advice will occur during macro expansion. To also affect | |
1729 | ;; the behavior during evaluation time one has to change the value of | |
1730 | ;; `ad-return-value' in a piece of after advice. For example: | |
1731 | ;; | |
1732 | ;; (defmacro foom (x) | |
1733 | ;; (` (list (, x)))) | |
1734 | ;; foom | |
1735 | ;; | |
1736 | ;; (foom '(a)) | |
1737 | ;; ((a)) | |
1738 | ;; | |
1739 | ;; (defadvice foom (before fg-print-x act) | |
1740 | ;; "Print the value of X." | |
1741 | ;; (print x)) | |
1742 | ;; foom | |
1743 | ;; | |
1744 | ;; The following works as expected because evaluation immediately follows | |
1745 | ;; macro expansion: | |
1746 | ;; | |
1747 | ;; (foom '(a)) | |
1748 | ;; (quote (a)) | |
1749 | ;; ((a)) | |
1750 | ;; | |
1751 | ;; However, the printing happens during expansion (or byte-compile) time: | |
1752 | ;; | |
1753 | ;; (macroexpand '(foom '(a))) | |
1754 | ;; (quote (a)) | |
1755 | ;; (list (quote (a))) | |
1756 | ;; | |
1757 | ;; If we want it to happen during evaluation time we have to do the | |
1758 | ;; following (first remove the old advice): | |
1759 | ;; | |
1760 | ;; (ad-remove-advice 'foom 'before 'fg-print-x) | |
1761 | ;; nil | |
1762 | ;; | |
1763 | ;; (defadvice foom (after fg-print-x act) | |
1764 | ;; "Print the value of X." | |
1765 | ;; (setq ad-return-value | |
1766 | ;; (` (progn (print (, x)) | |
1767 | ;; (, ad-return-value))))) | |
1768 | ;; foom | |
1769 | ;; | |
1770 | ;; (macroexpand '(foom '(a))) | |
1771 | ;; (progn (print (quote (a))) (list (quote (a)))) | |
1772 | ;; | |
1773 | ;; (foom '(a)) | |
1774 | ;; (a) | |
1775 | ;; ((a)) | |
1776 | ;; | |
1777 | ;; While this method might seem somewhat cumbersome, it is very general | |
1778 | ;; because it allows one to influence macro expansion as well as evaluation. | |
1779 | ;; In general, advising macros should be a rather rare activity anyway, in | |
1780 | ;; particular, because compile-time macro expansion takes away a lot of the | |
1781 | ;; flexibility and effectiveness of the advice mechanism. Macros that were | |
1782 | ;; compile-time expanded before the advice was activated will of course never | |
1783 | ;; exhibit the advised behavior. | |
1784 | ;; | |
1785 | ;; @@ Advising special forms: | |
1786 | ;; ========================== | |
1787 | ;; Now for something that should be even more rare than advising macros: | |
1788 | ;; Advising special forms. Because special forms are irregular in their | |
1789 | ;; argument evaluation behavior (e.g., `setq' evaluates the second but not | |
1790 | ;; the first argument) they have to be advised into macros. A dangerous | |
1791 | ;; consequence of this is that the byte-compiler will not recognize them | |
1792 | ;; as special forms anymore (well, in most cases) and use their expansion | |
1793 | ;; rather than the proper byte-code. Also, because the original definition | |
1794 | ;; of a special form cannot be `funcall'ed, `eval' has to be used instead | |
1795 | ;; which is less efficient. | |
1796 | ;; | |
1797 | ;; MORAL: Do not advise special forms unless you are completely sure about | |
1798 | ;; what you are doing (some of the forward advice behavior is | |
1799 | ;; implemented via advice of the special forms `defun' and `defmacro'). | |
1800 | ;; As a safety measure one should always do `ad-deactivate-all' before | |
1801 | ;; one byte-compiles a file to avoid any interference of advised | |
1802 | ;; special forms. | |
1803 | ;; | |
1804 | ;; Apart from the safety concerns advising special forms is not any different | |
1805 | ;; from advising plain functions or subrs. | |
1806 | ||
1807 | ||
ee7bf2ad RM |
1808 | ;;; Code: |
1809 | ||
1810 | ;; @ Advice implementation: | |
1811 | ;; ======================== | |
1812 | ||
1813 | ;; @@ Compilation idiosyncrasies: | |
1814 | ;; ============================== | |
1815 | ||
1816 | ;; `defadvice' expansion needs quite a few advice functions and variables, | |
6e2f6f45 | 1817 | ;; hence, I need to preload the file before it can be compiled. To avoid |
ee7bf2ad RM |
1818 | ;; interference of bogus compiled files I always preload the source file: |
1819 | (provide 'advice-preload) | |
1820 | ;; During a normal load this is a noop: | |
1821 | (require 'advice-preload "advice.el") | |
1822 | ||
ee7bf2ad | 1823 | |
f643a891 RS |
1824 | (defmacro ad-lemacs-p () |
1825 | ;;Expands into Non-nil constant if we run Lucid's version of Emacs-19. | |
1826 | ;;Unselected conditional code will be optimized away during compilation. | |
1827 | (string-match "Lucid" emacs-version)) | |
ee7bf2ad | 1828 | |
ee7bf2ad | 1829 | |
fabaa9b5 RS |
1830 | ;; @@ Variable definitions: |
1831 | ;; ======================== | |
1832 | ||
81eee8ab | 1833 | (defconst ad-version "2.14") |
ee7bf2ad RM |
1834 | |
1835 | ;;;###autoload | |
1836 | (defvar ad-redefinition-action 'warn | |
fabaa9b5 | 1837 | "*Defines what to do with redefinitions during Advice de/activation. |
ee7bf2ad RM |
1838 | Redefinition occurs if a previously activated function that already has an |
1839 | original definition associated with it gets redefined and then de/activated. | |
1840 | In such a case we can either accept the current definition as the new | |
1841 | original definition, discard the current definition and replace it with the | |
6e2f6f45 RS |
1842 | old original, or keep it and raise an error. The values `accept', `discard', |
1843 | `error' or `warn' govern what will be done. `warn' is just like `accept' but | |
1844 | it additionally prints a warning message. All other values will be | |
ee7bf2ad RM |
1845 | interpreted as `error'.") |
1846 | ||
1847 | ;;;###autoload | |
fabaa9b5 RS |
1848 | (defvar ad-default-compilation-action 'maybe |
1849 | "*Defines whether to compile advised definitions during activation. | |
1850 | A value of `always' will result in unconditional compilation, `never' will | |
1851 | always avoid compilation, `maybe' will compile if the byte-compiler is already | |
1852 | loaded, and `like-original' will compile if the original definition of the | |
1853 | advised function is compiled or a built-in function. Every other value will | |
1854 | be interpreted as `maybe'. This variable will only be considered if the | |
1855 | COMPILE argument of `ad-activate' was supplied as nil.") | |
ee7bf2ad RM |
1856 | |
1857 | ||
1858 | ;; @@ Some utilities: | |
1859 | ;; ================== | |
1860 | ||
1861 | ;; We don't want the local arguments to interfere with anything | |
1862 | ;; referenced in the supplied functions => the cryptic casing: | |
1863 | (defun ad-substitute-tree (sUbTrEe-TeSt fUnCtIoN tReE) | |
1864 | ;;"Substitutes qualifying subTREEs with result of FUNCTION(subTREE). | |
1865 | ;;Only proper subtrees are considered, for example, if TREE is (1 (2 (3)) 4) | |
1866 | ;;then the subtrees will be 1 (2 (3)) 2 (3) 3 4, dotted structures are | |
6e2f6f45 RS |
1867 | ;;allowed too. Once a qualifying subtree has been found its subtrees will |
1868 | ;;not be considered anymore. (ad-substitute-tree 'atom 'identity tree) | |
ee7bf2ad RM |
1869 | ;;generates a copy of TREE." |
1870 | (cond ((consp tReE) | |
1871 | (cons (if (funcall sUbTrEe-TeSt (car tReE)) | |
1872 | (funcall fUnCtIoN (car tReE)) | |
1873 | (if (consp (car tReE)) | |
1874 | (ad-substitute-tree sUbTrEe-TeSt fUnCtIoN (car tReE)) | |
1875 | (car tReE))) | |
1876 | (ad-substitute-tree sUbTrEe-TeSt fUnCtIoN (cdr tReE)))) | |
1877 | ((funcall sUbTrEe-TeSt tReE) | |
1878 | (funcall fUnCtIoN tReE)) | |
1879 | (t tReE))) | |
1880 | ||
1881 | ;; this is just faster than `ad-substitute-tree': | |
1882 | (defun ad-copy-tree (tree) | |
1883 | ;;"Returns a copy of the list structure of TREE." | |
1884 | (cond ((consp tree) | |
1885 | (cons (ad-copy-tree (car tree)) | |
1886 | (ad-copy-tree (cdr tree)))) | |
1887 | (t tree))) | |
1888 | ||
1889 | (defmacro ad-dolist (varform &rest body) | |
1890 | "A Common-Lisp-style dolist iterator with the following syntax: | |
1891 | ||
6e2f6f45 RS |
1892 | (ad-dolist (VAR INIT-FORM [RESULT-FORM]) |
1893 | BODY-FORM...) | |
ee7bf2ad | 1894 | |
6e2f6f45 RS |
1895 | which will iterate over the list yielded by INIT-FORM binding VAR to the |
1896 | current head at every iteration. If RESULT-FORM is supplied its value will | |
1897 | be returned at the end of the iteration, nil otherwise. The iteration can be | |
1898 | exited prematurely with `(ad-do-return [VALUE])'." | |
ee7bf2ad RM |
1899 | (let ((expansion |
1900 | (` (let ((ad-dO-vAr (, (car (cdr varform)))) | |
1901 | (, (car varform))) | |
1902 | (while ad-dO-vAr | |
1903 | (setq (, (car varform)) (car ad-dO-vAr)) | |
1904 | (,@ body) | |
1905 | ;;work around a backquote bug: | |
1906 | ;;(` ((,@ '(foo)) (bar))) => (append '(foo) '(((bar)))) wrong | |
1907 | ;;(` ((,@ '(foo)) (, '(bar)))) => (append '(foo) (list '(bar))) | |
1908 | (, '(setq ad-dO-vAr (cdr ad-dO-vAr)))) | |
1909 | (, (car (cdr (cdr varform)))))))) | |
1910 | ;;ok, this wastes some cons cells but only during compilation: | |
1911 | (if (catch 'contains-return | |
1912 | (ad-substitute-tree | |
1913 | (function (lambda (subtree) | |
1914 | (cond ((eq (car-safe subtree) 'ad-dolist)) | |
1915 | ((eq (car-safe subtree) 'ad-do-return) | |
1916 | (throw 'contains-return t))))) | |
1917 | 'identity body) | |
1918 | nil) | |
1919 | (` (catch 'ad-dO-eXiT (, expansion))) | |
1920 | expansion))) | |
1921 | ||
1922 | (defmacro ad-do-return (value) | |
1923 | (` (throw 'ad-dO-eXiT (, value)))) | |
1924 | ||
1925 | (if (not (get 'ad-dolist 'lisp-indent-hook)) | |
1926 | (put 'ad-dolist 'lisp-indent-hook 1)) | |
1927 | ||
1928 | ||
6e2f6f45 RS |
1929 | ;; @@ Save real definitions of subrs used by Advice: |
1930 | ;; ================================================= | |
1931 | ;; Advice depends on the real, unmodified functionality of various subrs, | |
1932 | ;; we save them here so advised versions will not interfere (eventually, | |
1933 | ;; we will save all subrs used in code generated by Advice): | |
1934 | ||
1935 | (defmacro ad-save-real-definition (function) | |
1936 | (let ((saved-function (intern (format "ad-real-%s" function)))) | |
1937 | ;; Make sure the compiler is loaded during macro expansion: | |
1938 | (require 'byte-compile "bytecomp") | |
1939 | (` (if (not (fboundp '(, saved-function))) | |
1940 | (progn (fset '(, saved-function) (symbol-function '(, function))) | |
1941 | ;; Copy byte-compiler properties: | |
1942 | (,@ (if (get function 'byte-compile) | |
1943 | (` ((put '(, saved-function) 'byte-compile | |
1944 | '(, (get function 'byte-compile))))))) | |
1945 | (,@ (if (get function 'byte-opcode) | |
1946 | (` ((put '(, saved-function) 'byte-opcode | |
1947 | '(, (get function 'byte-opcode)))))))))))) | |
1948 | ||
1949 | (defun ad-save-real-definitions () | |
1950 | ;; Macro expansion will hardcode the values of the various byte-compiler | |
1951 | ;; properties into the compiled version of this function such that the | |
1952 | ;; proper values will be available at runtime without loading the compiler: | |
1953 | (ad-save-real-definition fset) | |
fabaa9b5 | 1954 | (ad-save-real-definition documentation)) |
6e2f6f45 RS |
1955 | |
1956 | (ad-save-real-definitions) | |
1957 | ||
1958 | ||
ee7bf2ad RM |
1959 | ;; @@ Advice info access fns: |
1960 | ;; ========================== | |
1961 | ||
1962 | ;; Advice information for a particular function is stored on the | |
6e2f6f45 | 1963 | ;; advice-info property of the function symbol. It is stored as an |
ee7bf2ad RM |
1964 | ;; alist of the following format: |
1965 | ;; | |
1966 | ;; ((active . t/nil) | |
1967 | ;; (before adv1 adv2 ...) | |
1968 | ;; (around adv1 adv2 ...) | |
1969 | ;; (after adv1 adv2 ...) | |
1970 | ;; (activation adv1 adv2 ...) | |
1971 | ;; (deactivation adv1 adv2 ...) | |
1972 | ;; (origname . <symbol fbound to origdef>) | |
1973 | ;; (cache . (<advised-definition> . <id>))) | |
1974 | ||
1975 | ;; List of currently advised though not necessarily activated functions | |
1976 | ;; (this list is maintained as a completion table): | |
1977 | (defvar ad-advised-functions nil) | |
1978 | ||
1979 | (defmacro ad-pushnew-advised-function (function) | |
1980 | ;;"Add FUNCTION to `ad-advised-functions' unless its already there." | |
1981 | (` (if (not (assoc (symbol-name (, function)) ad-advised-functions)) | |
1982 | (setq ad-advised-functions | |
1983 | (cons (list (symbol-name (, function))) | |
1984 | ad-advised-functions))))) | |
1985 | ||
1986 | (defmacro ad-pop-advised-function (function) | |
1987 | ;;"Remove FUNCTION from `ad-advised-functions'." | |
1988 | (` (setq ad-advised-functions | |
1989 | (delq (assoc (symbol-name (, function)) ad-advised-functions) | |
1990 | ad-advised-functions)))) | |
1991 | ||
1992 | (defmacro ad-do-advised-functions (varform &rest body) | |
1993 | ;;"`ad-dolist'-style iterator that maps over `ad-advised-functions'. | |
6e2f6f45 RS |
1994 | ;; (ad-do-advised-functions (VAR [RESULT-FORM]) |
1995 | ;; BODY-FORM...) | |
1996 | ;;Also see `ad-dolist'. On each iteration VAR will be bound to the | |
ee7bf2ad RM |
1997 | ;;name of an advised function (a symbol)." |
1998 | (` (ad-dolist ((, (car varform)) | |
1999 | ad-advised-functions | |
2000 | (, (car (cdr varform)))) | |
2001 | (setq (, (car varform)) (intern (car (, (car varform))))) | |
2002 | (,@ body)))) | |
2003 | ||
2004 | (if (not (get 'ad-do-advised-functions 'lisp-indent-hook)) | |
2005 | (put 'ad-do-advised-functions 'lisp-indent-hook 1)) | |
2006 | ||
2007 | (defmacro ad-get-advice-info (function) | |
2008 | (` (get (, function) 'ad-advice-info))) | |
2009 | ||
2010 | (defmacro ad-set-advice-info (function advice-info) | |
2011 | (` (put (, function) 'ad-advice-info (, advice-info)))) | |
2012 | ||
2013 | (defmacro ad-copy-advice-info (function) | |
2014 | (` (ad-copy-tree (get (, function) 'ad-advice-info)))) | |
2015 | ||
2016 | (defmacro ad-is-advised (function) | |
6e2f6f45 | 2017 | ;;"Returns non-nil if FUNCTION has any advice info associated with it. |
ee7bf2ad RM |
2018 | ;;This does not mean that the advice is also active." |
2019 | (list 'ad-get-advice-info function)) | |
2020 | ||
2021 | (defun ad-initialize-advice-info (function) | |
2022 | ;;"Initializes the advice info for FUNCTION. | |
2023 | ;;Assumes that FUNCTION has not yet been advised." | |
2024 | (ad-pushnew-advised-function function) | |
2025 | (ad-set-advice-info function (list (cons 'active nil)))) | |
2026 | ||
2027 | (defmacro ad-get-advice-info-field (function field) | |
2028 | ;;"Retrieves the value of the advice info FIELD of FUNCTION." | |
2029 | (` (cdr (assq (, field) (ad-get-advice-info (, function)))))) | |
2030 | ||
2031 | (defun ad-set-advice-info-field (function field value) | |
2032 | ;;"Destructively modifies VALUE of the advice info FIELD of FUNCTION." | |
2033 | (and (ad-is-advised function) | |
2034 | (cond ((assq field (ad-get-advice-info function)) | |
2035 | ;; A field with that name is already present: | |
2036 | (rplacd (assq field (ad-get-advice-info function)) value)) | |
2037 | (t;; otherwise, create a new field with that name: | |
2038 | (nconc (ad-get-advice-info function) | |
2039 | (list (cons field value))))))) | |
2040 | ||
2041 | ;; Don't make this a macro so we can use it as a predicate: | |
2042 | (defun ad-is-active (function) | |
6e2f6f45 | 2043 | ;;"non-nil if FUNCTION is advised and activated." |
ee7bf2ad RM |
2044 | (ad-get-advice-info-field function 'active)) |
2045 | ||
2046 | ||
2047 | ;; @@ Access fns for single pieces of advice and related predicates: | |
2048 | ;; ================================================================= | |
2049 | ||
2050 | (defun ad-make-advice (name protect enable definition) | |
2051 | "Constructs single piece of advice to be stored in some advice-info. | |
6e2f6f45 | 2052 | NAME should be a non-nil symbol, PROTECT and ENABLE should each be |
ee7bf2ad | 2053 | either t or nil, and DEFINITION should be a list of the form |
6e2f6f45 | 2054 | `(advice lambda ARGLIST [DOCSTRING] [INTERACTIVE-FORM] BODY...)'." |
ee7bf2ad RM |
2055 | (list name protect enable definition)) |
2056 | ||
2057 | ;; ad-find-advice uses the alist structure directly -> | |
2058 | ;; change if this data structure changes!! | |
2059 | (defmacro ad-advice-name (advice) | |
2060 | (list 'car advice)) | |
2061 | (defmacro ad-advice-protected (advice) | |
2062 | (list 'nth 1 advice)) | |
2063 | (defmacro ad-advice-enabled (advice) | |
2064 | (list 'nth 2 advice)) | |
2065 | (defmacro ad-advice-definition (advice) | |
2066 | (list 'nth 3 advice)) | |
2067 | ||
2068 | (defun ad-advice-set-enabled (advice flag) | |
2069 | (rplaca (cdr (cdr advice)) flag)) | |
2070 | ||
2071 | (defun ad-class-p (thing) | |
2072 | (memq thing ad-advice-classes)) | |
2073 | (defun ad-name-p (thing) | |
2074 | (and thing (symbolp thing))) | |
2075 | (defun ad-position-p (thing) | |
2076 | (or (natnump thing) | |
2077 | (memq thing '(first last)))) | |
2078 | ||
2079 | ||
2080 | ;; @@ Advice access functions: | |
2081 | ;; =========================== | |
2082 | ||
2083 | ;; List of defined advice classes: | |
2084 | (defvar ad-advice-classes '(before around after activation deactivation)) | |
2085 | ||
2086 | (defun ad-has-enabled-advice (function class) | |
2087 | ;;"True if at least one of FUNCTION's advices in CLASS is enabled." | |
2088 | (ad-dolist (advice (ad-get-advice-info-field function class)) | |
2089 | (if (ad-advice-enabled advice) (ad-do-return t)))) | |
2090 | ||
2091 | (defun ad-has-redefining-advice (function) | |
2092 | ;;"True if FUNCTION's advice info defines at least 1 redefining advice. | |
2093 | ;;Redefining advices affect the construction of an advised definition." | |
2094 | (and (ad-is-advised function) | |
2095 | (or (ad-has-enabled-advice function 'before) | |
2096 | (ad-has-enabled-advice function 'around) | |
2097 | (ad-has-enabled-advice function 'after)))) | |
2098 | ||
2099 | (defun ad-has-any-advice (function) | |
2100 | ;;"True if the advice info of FUNCTION defines at least one advice." | |
2101 | (and (ad-is-advised function) | |
2102 | (ad-dolist (class ad-advice-classes nil) | |
2103 | (if (ad-get-advice-info-field function class) | |
2104 | (ad-do-return t))))) | |
2105 | ||
2106 | (defun ad-get-enabled-advices (function class) | |
2107 | ;;"Returns the list of enabled advices of FUNCTION in CLASS." | |
2108 | (let (enabled-advices) | |
2109 | (ad-dolist (advice (ad-get-advice-info-field function class)) | |
2110 | (if (ad-advice-enabled advice) | |
2111 | (setq enabled-advices (cons advice enabled-advices)))) | |
2112 | (reverse enabled-advices))) | |
2113 | ||
2114 | ||
fabaa9b5 RS |
2115 | ;; @@ Dealing with automatic advice activation via `fset/defalias': |
2116 | ;; ================================================================ | |
2117 | ||
2118 | ;; Since Emacs 19.26 the built-in versions of `fset' and `defalias' | |
2119 | ;; take care of automatic advice activation, hence, we don't have to | |
2120 | ;; hack it anymore by advising `fset/defun/defmacro/byte-code/etc'. | |
2121 | ||
2122 | ;; The functionality of the new `fset' is as follows: | |
2123 | ;; | |
2124 | ;; fset(sym,newdef) | |
2125 | ;; assign NEWDEF to SYM | |
2126 | ;; if (get SYM 'ad-advice-info) | |
2127 | ;; ad-activate(SYM, nil) | |
2128 | ;; return (symbol-function SYM) | |
2129 | ;; | |
2130 | ;; Whether advised definitions created by automatic activations will be | |
2131 | ;; compiled depends on the value of `ad-default-compilation-action'. | |
2132 | ||
2133 | ;; Since calling `ad-activate' in the built-in definition of `fset' can | |
2134 | ;; create major disasters we have to be a bit careful. One precaution is | |
2135 | ;; to provide a dummy definition for `ad-activate' which can be used to | |
2136 | ;; turn off automatic advice activation (e.g., when `ad-stop-advice' or | |
2137 | ;; `ad-recover-normality' are called). Another is to avoid recursive calls | |
2138 | ;; to `ad-activate-on' by using `ad-with-auto-activation-disabled' where | |
2139 | ;; appropriate, especially in a safe version of `fset'. | |
2140 | ||
2141 | ;; For now define `ad-activate' to the dummy definition: | |
2142 | (defun ad-activate (function &optional compile) | |
2143 | "Automatic advice activation is disabled. `ad-start-advice' enables it." | |
2144 | nil) | |
2145 | ||
2146 | ;; This is just a copy of the above: | |
2147 | (defun ad-activate-off (function &optional compile) | |
2148 | "Automatic advice activation is disabled. `ad-start-advice' enables it." | |
2149 | nil) | |
2150 | ||
2151 | ;; This will be t for top-level calls to `ad-activate-on': | |
2152 | (defvar ad-activate-on-top-level t) | |
2153 | ||
2154 | (defmacro ad-with-auto-activation-disabled (&rest body) | |
2155 | (` (let ((ad-activate-on-top-level nil)) | |
2156 | (,@ body)))) | |
2157 | ||
2158 | (defun ad-safe-fset (symbol definition) | |
2159 | ;; A safe `fset' which will never call `ad-activate' recursively. | |
2160 | (ad-with-auto-activation-disabled | |
2161 | (ad-real-fset symbol definition))) | |
2162 | ||
2163 | ||
ee7bf2ad RM |
2164 | ;; @@ Access functions for original definitions: |
2165 | ;; ============================================ | |
2166 | ;; The advice-info of an advised function contains its `origname' which is | |
2167 | ;; a symbol that is fbound to the original definition available at the first | |
6e2f6f45 | 2168 | ;; proper activation of the function after a legal re/definition. If the |
ee7bf2ad | 2169 | ;; original was defined via fcell indirection then `origname' will be defined |
6e2f6f45 | 2170 | ;; just so. Hence, to get hold of the actual original definition of a function |
ee7bf2ad RM |
2171 | ;; we need to use `ad-real-orig-definition'. |
2172 | ||
2173 | (defun ad-make-origname (function) | |
2174 | ;;"Makes name to be used to call the original FUNCTION." | |
2175 | (intern (format "ad-Orig-%s" function))) | |
2176 | ||
2177 | (defmacro ad-get-orig-definition (function) | |
2178 | (` (let ((origname (ad-get-advice-info-field (, function) 'origname))) | |
2179 | (if (fboundp origname) | |
2180 | (symbol-function origname))))) | |
2181 | ||
2182 | (defmacro ad-set-orig-definition (function definition) | |
fabaa9b5 | 2183 | (` (ad-safe-fset |
ee7bf2ad RM |
2184 | (ad-get-advice-info-field function 'origname) (, definition)))) |
2185 | ||
2186 | (defmacro ad-clear-orig-definition (function) | |
2187 | (` (fmakunbound (ad-get-advice-info-field (, function) 'origname)))) | |
2188 | ||
2189 | ||
2190 | ;; @@ Interactive input functions: | |
2191 | ;; =============================== | |
2192 | ||
2193 | (defun ad-read-advised-function (&optional prompt predicate default) | |
2194 | ;;"Reads name of advised function with completion from the minibuffer. | |
6e2f6f45 RS |
2195 | ;;An optional PROMPT will be used to prompt for the function. PREDICATE |
2196 | ;;plays the same role as for `try-completion' (which see). DEFAULT will | |
ee7bf2ad | 2197 | ;;be returned on empty input (defaults to the first advised function for |
6e2f6f45 | 2198 | ;;which PREDICATE returns non-nil)." |
ee7bf2ad RM |
2199 | (if (null ad-advised-functions) |
2200 | (error "ad-read-advised-function: There are no advised functions")) | |
2201 | (setq default | |
2202 | (or default | |
2203 | (ad-do-advised-functions (function) | |
2204 | (if (or (null predicate) | |
2205 | (funcall predicate function)) | |
2206 | (ad-do-return function))) | |
2207 | (error "ad-read-advised-function: %s" | |
2208 | "There are no qualifying advised functions"))) | |
2209 | (let* ((ad-pReDiCaTe predicate) | |
2210 | (function | |
2211 | (completing-read | |
2212 | (format "%s(default %s) " (or prompt "Function: ") default) | |
2213 | ad-advised-functions | |
2214 | (if predicate | |
2215 | (function | |
2216 | (lambda (function) | |
2217 | ;; Oops, no closures - the joys of dynamic scoping: | |
2218 | ;; `predicate' clashed with the `predicate' argument | |
2219 | ;; of Lemacs' `completing-read'..... | |
2220 | (funcall ad-pReDiCaTe (intern (car function)))))) | |
2221 | t))) | |
2222 | (if (equal function "") | |
2223 | (if (ad-is-advised default) | |
2224 | default | |
2225 | (error "ad-read-advised-function: `%s' is not advised" default)) | |
2226 | (intern function)))) | |
2227 | ||
2228 | (defvar ad-advice-class-completion-table | |
2229 | (mapcar '(lambda (class) (list (symbol-name class))) | |
2230 | ad-advice-classes)) | |
2231 | ||
2232 | (defun ad-read-advice-class (function &optional prompt default) | |
2233 | ;;"Reads a legal advice class with completion from the minibuffer. | |
6e2f6f45 | 2234 | ;;An optional PROMPT will be used to prompt for the class. DEFAULT will |
ee7bf2ad RM |
2235 | ;;be returned on empty input (defaults to the first non-empty advice |
2236 | ;;class of FUNCTION)." | |
2237 | (setq default | |
2238 | (or default | |
2239 | (ad-dolist (class ad-advice-classes) | |
2240 | (if (ad-get-advice-info-field function class) | |
2241 | (ad-do-return class))) | |
2242 | (error "ad-read-advice-class: `%s' has no advices" function))) | |
2243 | (let ((class (completing-read | |
2244 | (format "%s(default %s) " (or prompt "Class: ") default) | |
2245 | ad-advice-class-completion-table nil t))) | |
2246 | (if (equal class "") | |
2247 | default | |
2248 | (intern class)))) | |
2249 | ||
2250 | (defun ad-read-advice-name (function class &optional prompt) | |
2251 | ;;"Reads name of existing advice of CLASS for FUNCTION with completion. | |
2252 | ;;An optional PROMPT is used to prompt for the name." | |
2253 | (let* ((name-completion-table | |
2254 | (mapcar (function (lambda (advice) | |
2255 | (list (symbol-name (ad-advice-name advice))))) | |
2256 | (ad-get-advice-info-field function class))) | |
2257 | (default | |
2258 | (if (null name-completion-table) | |
2259 | (error "ad-read-advice-name: `%s' has no %s advice" | |
2260 | function class) | |
2261 | (car (car name-completion-table)))) | |
2262 | (prompt (format "%s(default %s) " (or prompt "Name: ") default)) | |
2263 | (name (completing-read prompt name-completion-table nil t))) | |
2264 | (if (equal name "") | |
2265 | (intern default) | |
2266 | (intern name)))) | |
2267 | ||
2268 | (defun ad-read-advice-specification (&optional prompt) | |
2269 | ;;"Reads a complete function/class/name specification from minibuffer. | |
6e2f6f45 | 2270 | ;;The list of read symbols will be returned. The optional PROMPT will |
ee7bf2ad RM |
2271 | ;;be used to prompt for the function." |
2272 | (let* ((function (ad-read-advised-function prompt)) | |
2273 | (class (ad-read-advice-class function)) | |
2274 | (name (ad-read-advice-name function class))) | |
2275 | (list function class name))) | |
2276 | ||
2277 | ;; Use previous regexp as a default: | |
2278 | (defvar ad-last-regexp "") | |
2279 | ||
2280 | (defun ad-read-regexp (&optional prompt) | |
2281 | ;;"Reads a regular expression from the minibuffer." | |
2282 | (let ((regexp (read-from-minibuffer | |
2283 | (concat (or prompt "Regular expression: ") | |
2284 | (if (equal ad-last-regexp "") "" | |
2285 | (format "(default \"%s\") " ad-last-regexp)))))) | |
2286 | (setq ad-last-regexp | |
2287 | (if (equal regexp "") ad-last-regexp regexp)))) | |
2288 | ||
2289 | ||
2290 | ;; @@ Finding, enabling, adding and removing pieces of advice: | |
2291 | ;; =========================================================== | |
2292 | ||
2293 | (defmacro ad-find-advice (function class name) | |
2294 | ;;"Finds the first advice of FUNCTION in CLASS with NAME." | |
2295 | (` (assq (, name) (ad-get-advice-info-field (, function) (, class))))) | |
2296 | ||
2297 | (defun ad-advice-position (function class name) | |
2298 | ;;"Returns position of first advice of FUNCTION in CLASS with NAME." | |
2299 | (let* ((found-advice (ad-find-advice function class name)) | |
2300 | (advices (ad-get-advice-info-field function class))) | |
2301 | (if found-advice | |
2302 | (- (length advices) (length (memq found-advice advices)))))) | |
2303 | ||
2304 | (defun ad-find-some-advice (function class name) | |
2305 | "Finds the first of FUNCTION's advices in CLASS matching NAME. | |
2306 | NAME can be a symbol or a regular expression matching part of an advice name. | |
2307 | If CLASS is `any' all legal advice classes will be checked." | |
2308 | (if (ad-is-advised function) | |
2309 | (let (found-advice) | |
2310 | (ad-dolist (advice-class ad-advice-classes) | |
2311 | (if (or (eq class 'any) (eq advice-class class)) | |
2312 | (setq found-advice | |
2313 | (ad-dolist (advice (ad-get-advice-info-field | |
2314 | function advice-class)) | |
2315 | (if (or (and (stringp name) | |
2316 | (string-match | |
2317 | name (symbol-name | |
2318 | (ad-advice-name advice)))) | |
2319 | (eq name (ad-advice-name advice))) | |
2320 | (ad-do-return advice))))) | |
2321 | (if found-advice (ad-do-return found-advice)))))) | |
2322 | ||
2323 | (defun ad-enable-advice-internal (function class name flag) | |
2324 | ;;"Sets enable FLAG of FUNCTION's advices in CLASS matching NAME. | |
2325 | ;;If NAME is a string rather than a symbol then it's interpreted as a regular | |
2326 | ;;expression and all advices whose name contain a match for it will be | |
6e2f6f45 RS |
2327 | ;;affected. If CLASS is `any' advices in all legal advice classes will be |
2328 | ;;considered. The number of changed advices will be returned (or nil if | |
ee7bf2ad RM |
2329 | ;;FUNCTION was not advised)." |
2330 | (if (ad-is-advised function) | |
2331 | (let ((matched-advices 0)) | |
2332 | (ad-dolist (advice-class ad-advice-classes) | |
2333 | (if (or (eq class 'any) (eq advice-class class)) | |
2334 | (ad-dolist (advice (ad-get-advice-info-field | |
2335 | function advice-class)) | |
2336 | (cond ((or (and (stringp name) | |
2337 | (string-match | |
2338 | name (symbol-name (ad-advice-name advice)))) | |
2339 | (eq name (ad-advice-name advice))) | |
2340 | (setq matched-advices (1+ matched-advices)) | |
2341 | (ad-advice-set-enabled advice flag)))))) | |
2342 | matched-advices))) | |
2343 | ||
2344 | (defun ad-enable-advice (function class name) | |
2345 | "Enables the advice of FUNCTION with CLASS and NAME." | |
2346 | (interactive (ad-read-advice-specification "Enable advice of: ")) | |
2347 | (if (ad-is-advised function) | |
2348 | (if (eq (ad-enable-advice-internal function class name t) 0) | |
2349 | (error "ad-enable-advice: `%s' has no %s advice matching `%s'" | |
2350 | function class name)) | |
2351 | (error "ad-enable-advice: `%s' is not advised" function))) | |
2352 | ||
2353 | (defun ad-disable-advice (function class name) | |
2354 | "Disables the advice of FUNCTION with CLASS and NAME." | |
2355 | (interactive (ad-read-advice-specification "Disable advice of: ")) | |
2356 | (if (ad-is-advised function) | |
2357 | (if (eq (ad-enable-advice-internal function class name nil) 0) | |
2358 | (error "ad-disable-advice: `%s' has no %s advice matching `%s'" | |
2359 | function class name)) | |
2360 | (error "ad-disable-advice: `%s' is not advised" function))) | |
2361 | ||
2362 | (defun ad-enable-regexp-internal (regexp class flag) | |
2363 | ;;"Sets enable FLAGs of all CLASS advices whose name contains a REGEXP match. | |
6e2f6f45 | 2364 | ;;If CLASS is `any' all legal advice classes are considered. The number of |
ee7bf2ad RM |
2365 | ;;affected advices will be returned." |
2366 | (let ((matched-advices 0)) | |
2367 | (ad-do-advised-functions (advised-function) | |
2368 | (setq matched-advices | |
2369 | (+ matched-advices | |
2370 | (or (ad-enable-advice-internal | |
2371 | advised-function class regexp flag) | |
2372 | 0)))) | |
2373 | matched-advices)) | |
2374 | ||
2375 | (defun ad-enable-regexp (regexp) | |
2376 | "Enables all advices with names that contain a match for REGEXP. | |
2377 | All currently advised functions will be considered." | |
2378 | (interactive | |
2379 | (list (ad-read-regexp "Enable advices via regexp: "))) | |
2380 | (let ((matched-advices (ad-enable-regexp-internal regexp 'any t))) | |
2381 | (if (interactive-p) | |
2382 | (message "%d matching advices enabled" matched-advices)) | |
2383 | matched-advices)) | |
2384 | ||
2385 | (defun ad-disable-regexp (regexp) | |
2386 | "Disables all advices with names that contain a match for REGEXP. | |
2387 | All currently advised functions will be considered." | |
2388 | (interactive | |
2389 | (list (ad-read-regexp "Disable advices via regexp: "))) | |
2390 | (let ((matched-advices (ad-enable-regexp-internal regexp 'any nil))) | |
2391 | (if (interactive-p) | |
2392 | (message "%d matching advices disabled" matched-advices)) | |
2393 | matched-advices)) | |
2394 | ||
2395 | (defun ad-remove-advice (function class name) | |
2396 | "Removes FUNCTION's advice with NAME from its advices in CLASS. | |
2397 | If such an advice was found it will be removed from the list of advices | |
2398 | in that CLASS." | |
2399 | (interactive (ad-read-advice-specification "Remove advice of: ")) | |
2400 | (if (ad-is-advised function) | |
2401 | (let* ((advice-to-remove (ad-find-advice function class name))) | |
2402 | (if advice-to-remove | |
2403 | (ad-set-advice-info-field | |
2404 | function class | |
2405 | (delq advice-to-remove (ad-get-advice-info-field function class))) | |
2406 | (error "ad-remove-advice: `%s' has no %s advice `%s'" | |
2407 | function class name))) | |
2408 | (error "ad-remove-advice: `%s' is not advised" function))) | |
2409 | ||
2410 | ;;;###autoload | |
2411 | (defun ad-add-advice (function advice class position) | |
2412 | "Adds a piece of ADVICE to FUNCTION's list of advices in CLASS. | |
2413 | If FUNCTION already has one or more pieces of advice of the specified | |
6e2f6f45 | 2414 | CLASS then POSITION determines where the new piece will go. The value |
ee7bf2ad | 2415 | of POSITION can either be `first', `last' or a number where 0 corresponds |
6e2f6f45 RS |
2416 | to `first'. Numbers outside the range will be mapped to the closest |
2417 | extreme position. If there was already a piece of ADVICE with the same | |
ee7bf2ad RM |
2418 | name, then the position argument will be ignored and the old advice |
2419 | will be overwritten with the new one. | |
2420 | If the FUNCTION was not advised already, then its advice info will be | |
6e2f6f45 | 2421 | initialized. Redefining a piece of advice whose name is part of the cache-id |
ee7bf2ad RM |
2422 | will clear the cache." |
2423 | (cond ((not (ad-is-advised function)) | |
2424 | (ad-initialize-advice-info function) | |
2425 | (ad-set-advice-info-field | |
2426 | function 'origname (ad-make-origname function)))) | |
2427 | (let* ((previous-position | |
2428 | (ad-advice-position function class (ad-advice-name advice))) | |
2429 | (advices (ad-get-advice-info-field function class)) | |
2430 | ;; Determine a numerical position for the new advice: | |
2431 | (position (cond (previous-position) | |
2432 | ((eq position 'first) 0) | |
2433 | ((eq position 'last) (length advices)) | |
2434 | ((numberp position) | |
2435 | (max 0 (min position (length advices)))) | |
2436 | (t 0)))) | |
2437 | ;; Check whether we have to clear the cache: | |
2438 | (if (memq (ad-advice-name advice) (ad-get-cache-class-id function class)) | |
2439 | (ad-clear-cache function)) | |
2440 | (if previous-position | |
2441 | (setcar (nthcdr position advices) advice) | |
2442 | (if (= position 0) | |
2443 | (ad-set-advice-info-field function class (cons advice advices)) | |
2444 | (setcdr (nthcdr (1- position) advices) | |
2445 | (cons advice (nthcdr position advices))))))) | |
2446 | ||
2447 | ||
2448 | ;; @@ Accessing and manipulating function definitions: | |
2449 | ;; =================================================== | |
2450 | ||
2451 | (defmacro ad-macrofy (definition) | |
2452 | ;;"Takes a lambda function DEFINITION and makes a macro out of it." | |
2453 | (` (cons 'macro (, definition)))) | |
2454 | ||
2455 | (defmacro ad-lambdafy (definition) | |
2456 | ;;"Takes a macro function DEFINITION and makes a lambda out of it." | |
2457 | (` (cdr (, definition)))) | |
2458 | ||
2459 | ;; There is no way to determine whether some subr is a special form or not, | |
6e2f6f45 | 2460 | ;; hence we need this list (which is probably out of date): |
ee7bf2ad RM |
2461 | (defvar ad-special-forms |
2462 | (mapcar 'symbol-function | |
2463 | '(and catch cond condition-case defconst defmacro | |
2464 | defun defvar function if interactive let let* | |
2465 | or prog1 prog2 progn quote save-excursion | |
2466 | save-restriction save-window-excursion setq | |
2467 | setq-default unwind-protect while | |
2468 | with-output-to-temp-buffer))) | |
2469 | ||
2470 | (defmacro ad-special-form-p (definition) | |
6e2f6f45 | 2471 | ;;"non-nil if DEFINITION is a special form." |
ee7bf2ad RM |
2472 | (list 'memq definition 'ad-special-forms)) |
2473 | ||
2474 | (defmacro ad-interactive-p (definition) | |
6e2f6f45 | 2475 | ;;"non-nil if DEFINITION can be called interactively." |
ee7bf2ad RM |
2476 | (list 'commandp definition)) |
2477 | ||
2478 | (defmacro ad-subr-p (definition) | |
6e2f6f45 | 2479 | ;;"non-nil if DEFINITION is a subr." |
ee7bf2ad RM |
2480 | (list 'subrp definition)) |
2481 | ||
2482 | (defmacro ad-macro-p (definition) | |
6e2f6f45 | 2483 | ;;"non-nil if DEFINITION is a macro." |
ee7bf2ad RM |
2484 | (` (eq (car-safe (, definition)) 'macro))) |
2485 | ||
2486 | (defmacro ad-lambda-p (definition) | |
6e2f6f45 | 2487 | ;;"non-nil if DEFINITION is a lambda expression." |
ee7bf2ad RM |
2488 | (` (eq (car-safe (, definition)) 'lambda))) |
2489 | ||
2490 | ;; see ad-make-advice for the format of advice definitions: | |
2491 | (defmacro ad-advice-p (definition) | |
6e2f6f45 | 2492 | ;;"non-nil if DEFINITION is a piece of advice." |
ee7bf2ad RM |
2493 | (` (eq (car-safe (, definition)) 'advice))) |
2494 | ||
6e2f6f45 RS |
2495 | ;; Emacs/Lemacs cross-compatibility |
2496 | ;; (compiled-function-p is an obsolete function in Emacs): | |
ee7bf2ad RM |
2497 | (if (and (not (fboundp 'byte-code-function-p)) |
2498 | (fboundp 'compiled-function-p)) | |
fabaa9b5 | 2499 | (ad-safe-fset 'byte-code-function-p 'compiled-function-p)) |
ee7bf2ad | 2500 | |
6e2f6f45 RS |
2501 | (defmacro ad-compiled-p (definition) |
2502 | ;;"non-nil if DEFINITION is a compiled byte-code object." | |
2503 | (` (or (byte-code-function-p (, definition)) | |
2504 | (and (ad-macro-p (, definition)) | |
2505 | (byte-code-function-p (ad-lambdafy (, definition))))))) | |
ee7bf2ad | 2506 | |
6e2f6f45 RS |
2507 | (defmacro ad-compiled-code (compiled-definition) |
2508 | ;;"Returns the byte-code object of a COMPILED-DEFINITION." | |
ee7bf2ad RM |
2509 | (` (if (ad-macro-p (, compiled-definition)) |
2510 | (ad-lambdafy (, compiled-definition)) | |
2511 | (, compiled-definition)))) | |
2512 | ||
2513 | (defun ad-lambda-expression (definition) | |
2514 | ;;"Returns the lambda expression of a function/macro/advice DEFINITION." | |
2515 | (cond ((ad-lambda-p definition) | |
2516 | definition) | |
2517 | ((ad-macro-p definition) | |
2518 | (ad-lambdafy definition)) | |
2519 | ((ad-advice-p definition) | |
2520 | (cdr definition)) | |
2521 | (t nil))) | |
2522 | ||
2523 | (defun ad-arglist (definition &optional name) | |
2524 | ;;"Returns the argument list of DEFINITION. | |
2525 | ;;If DEFINITION could be from a subr then its NAME should be | |
2526 | ;;supplied to make subr arglist lookup more efficient." | |
6e2f6f45 RS |
2527 | (cond ((ad-compiled-p definition) |
2528 | (aref (ad-compiled-code definition) 0)) | |
ee7bf2ad RM |
2529 | ((consp definition) |
2530 | (car (cdr (ad-lambda-expression definition)))) | |
2531 | ((ad-subr-p definition) | |
2532 | (if name | |
2533 | (ad-subr-arglist name) | |
2534 | ;; otherwise get it from its printed representation: | |
2535 | (setq name (format "%s" definition)) | |
2536 | (string-match "^#<subr \\([^>]+\\)>$" name) | |
2537 | (ad-subr-arglist | |
2538 | (intern (substring name (match-beginning 1) (match-end 1)))))))) | |
2539 | ||
2540 | ;; Store subr-args as `((arg1 arg2 ...))' so I can distinguish | |
2541 | ;; a defined empty arglist `(nil)' from an undefined arglist: | |
2542 | (defmacro ad-define-subr-args (subr arglist) | |
2543 | (` (put (, subr) 'ad-subr-arglist (list (, arglist))))) | |
2544 | (defmacro ad-undefine-subr-args (subr) | |
2545 | (` (put (, subr) 'ad-subr-arglist nil))) | |
2546 | (defmacro ad-subr-args-defined-p (subr) | |
2547 | (` (get (, subr) 'ad-subr-arglist))) | |
2548 | (defmacro ad-get-subr-args (subr) | |
2549 | (` (car (get (, subr) 'ad-subr-arglist)))) | |
2550 | ||
2551 | (defun ad-subr-arglist (subr-name) | |
2552 | ;;"Retrieve arglist of the subr with SUBR-NAME. | |
6e2f6f45 RS |
2553 | ;;Either use the one stored under the `ad-subr-arglist' property, |
2554 | ;;or try to retrieve it from the docstring and cache it under | |
ee7bf2ad | 2555 | ;;that property, or otherwise use `(&rest ad-subr-args)'." |
6e2f6f45 RS |
2556 | (cond ((ad-subr-args-defined-p subr-name) |
2557 | (ad-get-subr-args subr-name)) | |
2558 | ;; says jwz: Should use this for Lemacs 19.8 and above: | |
2559 | ;;((fboundp 'subr-min-args) | |
2560 | ;; ...) | |
2561 | ;; says hans: I guess what Jamie means is that I should use the values | |
2562 | ;; of `subr-min-args' and `subr-max-args' to construct the subr arglist | |
2563 | ;; without having to look it up via parsing the docstring, e.g., | |
2564 | ;; values 1 and 2 would suggest `(arg1 &optional arg2)' as an | |
2565 | ;; argument list. However, that won't work because there is no | |
2566 | ;; way to distinguish a subr with args `(a &optional b &rest c)' from | |
2567 | ;; one with args `(a &rest c)' using that mechanism. Also, the argument | |
2568 | ;; names from the docstring are more meaningful. Hence, I'll stick with | |
2569 | ;; the old way of doing things. | |
81eee8ab RS |
2570 | (t (let ((doc (or (ad-real-documentation subr-name t) ""))) |
2571 | (cond ((string-match "^\\(([^\)]+)\\)\n?\\'" doc) | |
2572 | (ad-define-subr-args | |
2573 | subr-name | |
2574 | (cdr (car (read-from-string | |
2575 | (downcase | |
2576 | (substring doc | |
2577 | (match-beginning 1) | |
2578 | (match-end 1))))))) | |
2579 | (ad-get-subr-args subr-name)) | |
2580 | ;; this is the old format used before Emacs 19.24: | |
2581 | ((string-match | |
2582 | "[\n\t ]*\narguments: ?\\((.*)\\)\n?\\'" doc) | |
6e2f6f45 RS |
2583 | (ad-define-subr-args |
2584 | subr-name | |
2585 | (car (read-from-string | |
2586 | doc (match-beginning 1) (match-end 1)))) | |
2587 | (ad-get-subr-args subr-name)) | |
2588 | (t '(&rest ad-subr-args))))))) | |
ee7bf2ad RM |
2589 | |
2590 | (defun ad-docstring (definition) | |
2591 | ;;"Returns the unexpanded docstring of DEFINITION." | |
2592 | (let ((docstring | |
6e2f6f45 RS |
2593 | (if (ad-compiled-p definition) |
2594 | (ad-real-documentation definition t) | |
ee7bf2ad RM |
2595 | (car (cdr (cdr (ad-lambda-expression definition))))))) |
2596 | (if (or (stringp docstring) | |
2597 | (natnump docstring)) | |
2598 | docstring))) | |
2599 | ||
2600 | (defun ad-interactive-form (definition) | |
2601 | ;;"Returns the interactive form of DEFINITION." | |
6e2f6f45 | 2602 | (cond ((ad-compiled-p definition) |
ee7bf2ad | 2603 | (and (commandp definition) |
6e2f6f45 | 2604 | (list 'interactive (aref (ad-compiled-code definition) 5)))) |
ee7bf2ad RM |
2605 | ((or (ad-advice-p definition) |
2606 | (ad-lambda-p definition)) | |
2607 | (commandp (ad-lambda-expression definition))))) | |
2608 | ||
2609 | (defun ad-body-forms (definition) | |
2610 | ;;"Returns the list of body forms of DEFINITION." | |
6e2f6f45 RS |
2611 | (cond ((ad-compiled-p definition) |
2612 | nil) | |
ee7bf2ad RM |
2613 | ((consp definition) |
2614 | (nthcdr (+ (if (ad-docstring definition) 1 0) | |
2615 | (if (ad-interactive-form definition) 1 0)) | |
2616 | (cdr (cdr (ad-lambda-expression definition))))))) | |
2617 | ||
ee7bf2ad RM |
2618 | ;; Matches the docstring of an advised definition. |
2619 | ;; The first group of the regexp matches the function name: | |
2620 | (defvar ad-advised-definition-docstring-regexp "^\\$ad-doc: \\(.+\\)\\$$") | |
2621 | ||
2622 | (defun ad-make-advised-definition-docstring (function) | |
2623 | ;; Makes an identifying docstring for the advised definition of FUNCTION. | |
2624 | ;; Put function name into the documentation string so we can infer | |
6e2f6f45 | 2625 | ;; the name of the advised function from the docstring. This is needed |
ee7bf2ad RM |
2626 | ;; to generate a proper advised docstring even if we are just given a |
2627 | ;; definition (also see the defadvice for `documentation'): | |
2628 | (format "$ad-doc: %s$" (prin1-to-string function))) | |
2629 | ||
2630 | (defun ad-advised-definition-p (definition) | |
6e2f6f45 | 2631 | ;;"non-nil if DEFINITION was generated from advice information." |
ee7bf2ad RM |
2632 | (if (or (ad-lambda-p definition) |
2633 | (ad-macro-p definition) | |
2634 | (ad-compiled-p definition)) | |
2635 | (let ((docstring (ad-docstring definition))) | |
2636 | (and (stringp docstring) | |
2637 | (string-match | |
2638 | ad-advised-definition-docstring-regexp docstring))))) | |
2639 | ||
2640 | (defun ad-definition-type (definition) | |
2641 | ;;"Returns symbol that describes the type of DEFINITION." | |
2642 | (if (ad-macro-p definition) | |
2643 | 'macro | |
2644 | (if (ad-subr-p definition) | |
2645 | (if (ad-special-form-p definition) | |
2646 | 'special-form | |
2647 | 'subr) | |
2648 | (if (or (ad-lambda-p definition) | |
2649 | (ad-compiled-p definition)) | |
2650 | 'function | |
2651 | (if (ad-advice-p definition) | |
2652 | 'advice))))) | |
2653 | ||
2654 | (defun ad-has-proper-definition (function) | |
2655 | ;;"True if FUNCTION is a symbol with a proper definition. | |
2656 | ;;For that it has to be fbound with a non-autoload definition." | |
2657 | (and (symbolp function) | |
2658 | (fboundp function) | |
2659 | (not (eq (car-safe (symbol-function function)) 'autoload)))) | |
2660 | ||
2661 | ;; The following two are necessary for the sake of packages such as | |
2662 | ;; ange-ftp which redefine functions via fcell indirection: | |
2663 | (defun ad-real-definition (function) | |
2664 | ;;"Finds FUNCTION's definition at the end of function cell indirection." | |
2665 | (if (ad-has-proper-definition function) | |
2666 | (let ((definition (symbol-function function))) | |
2667 | (if (symbolp definition) | |
2668 | (ad-real-definition definition) | |
2669 | definition)))) | |
2670 | ||
2671 | (defun ad-real-orig-definition (function) | |
2672 | ;;"Finds FUNCTION's real original definition starting from its `origname'." | |
2673 | (if (ad-is-advised function) | |
2674 | (ad-real-definition (ad-get-advice-info-field function 'origname)))) | |
2675 | ||
2676 | (defun ad-is-compilable (function) | |
2677 | ;;"True if FUNCTION has an interpreted definition that can be compiled." | |
2678 | (and (ad-has-proper-definition function) | |
2679 | (or (ad-lambda-p (symbol-function function)) | |
2680 | (ad-macro-p (symbol-function function))) | |
2681 | (not (ad-compiled-p (symbol-function function))))) | |
2682 | ||
ee7bf2ad RM |
2683 | (defun ad-compile-function (function) |
2684 | "Byte-compiles FUNCTION (or macro) if it is not yet compiled." | |
2685 | (interactive "aByte-compile function: ") | |
2686 | (if (ad-is-compilable function) | |
fabaa9b5 RS |
2687 | ;; Need to turn off auto-activation |
2688 | ;; because `byte-compile' uses `fset': | |
2689 | (ad-with-auto-activation-disabled | |
2690 | (byte-compile function)))) | |
ee7bf2ad RM |
2691 | |
2692 | ||
2693 | ;; @@ Constructing advised definitions: | |
2694 | ;; ==================================== | |
2695 | ;; | |
2696 | ;; Main design decisions about the form of advised definitions: | |
2697 | ;; | |
2698 | ;; A) How will original definitions be called? | |
2699 | ;; B) What will argument lists of advised functions look like? | |
2700 | ;; | |
2701 | ;; Ad A) | |
2702 | ;; I chose to use function indirection for all four types of original | |
2703 | ;; definitions (functions, macros, subrs and special forms), i.e., create | |
2704 | ;; a unique symbol `ad-Orig-<name>' which is fbound to the original | |
6e2f6f45 | 2705 | ;; definition and call it according to type and arguments. Functions and |
ee7bf2ad | 2706 | ;; subrs that don't have any &rest arguments can be called directly in a |
6e2f6f45 RS |
2707 | ;; `(ad-Orig-<name> ....)' form. If they have a &rest argument we have to |
2708 | ;; use `apply'. Macros will be called with | |
ee7bf2ad RM |
2709 | ;; `(macroexpand '(ad-Orig-<name> ....))', and special forms also need a |
2710 | ;; form like that with `eval' instead of `macroexpand'. | |
2711 | ;; | |
2712 | ;; Ad B) | |
2713 | ;; Use original arguments where possible and `(&rest ad-subr-args)' | |
2714 | ;; otherwise, even though this seems to be more complicated and less | |
2715 | ;; uniform than a general `(&rest args)' approach. My reason to still | |
2716 | ;; do it that way is that in most cases my approach leads to the more | |
2717 | ;; efficient form for the advised function, and portability (e.g., to | |
2718 | ;; make the same advice work regardless of whether something is a | |
2719 | ;; function or a subr) can still be achieved with argument access macros. | |
2720 | ||
2721 | ||
2722 | (defun ad-prognify (forms) | |
2723 | (cond ((<= (length forms) 1) | |
2724 | (car forms)) | |
2725 | (t (cons 'progn forms)))) | |
2726 | ||
2727 | ;; @@@ Accessing argument lists: | |
2728 | ;; ============================= | |
2729 | ||
2730 | (defun ad-parse-arglist (arglist) | |
2731 | ;;"Parses ARGLIST into its required, optional and rest parameters. | |
2732 | ;;A three-element list is returned, where the 1st element is the list of | |
2733 | ;;required arguments, the 2nd is the list of optional arguments, and the 3rd | |
6e2f6f45 | 2734 | ;;is the name of an optional rest parameter (or nil)." |
ee7bf2ad RM |
2735 | (let* (required optional rest) |
2736 | (setq rest (car (cdr (memq '&rest arglist)))) | |
2737 | (if rest (setq arglist (reverse (cdr (memq '&rest (reverse arglist)))))) | |
2738 | (setq optional (cdr (memq '&optional arglist))) | |
2739 | (if optional | |
2740 | (setq required (reverse (cdr (memq '&optional (reverse arglist))))) | |
2741 | (setq required arglist)) | |
2742 | (list required optional rest))) | |
2743 | ||
2744 | (defun ad-retrieve-args-form (arglist) | |
2745 | ;;"Generates a form which evaluates into names/values/types of ARGLIST. | |
2746 | ;;When the form gets evaluated within a function with that argument list | |
2747 | ;;it will result in a list with one entry for each argument, where the | |
2748 | ;;first element of each entry is the name of the argument, the second | |
2749 | ;;element is its actual current value, and the third element is either | |
2750 | ;;`required', `optional' or `rest' depending on the type of the argument." | |
2751 | (let* ((parsed-arglist (ad-parse-arglist arglist)) | |
2752 | (rest (nth 2 parsed-arglist))) | |
2753 | (` (list | |
2754 | (,@ (mapcar (function | |
2755 | (lambda (req) | |
2756 | (` (list '(, req) (, req) 'required)))) | |
2757 | (nth 0 parsed-arglist))) | |
2758 | (,@ (mapcar (function | |
2759 | (lambda (opt) | |
2760 | (` (list '(, opt) (, opt) 'optional)))) | |
2761 | (nth 1 parsed-arglist))) | |
2762 | (,@ (if rest (list (` (list '(, rest) (, rest) 'rest))))) | |
2763 | )))) | |
2764 | ||
2765 | (defun ad-arg-binding-field (binding field) | |
2766 | (cond ((eq field 'name) (car binding)) | |
2767 | ((eq field 'value) (car (cdr binding))) | |
2768 | ((eq field 'type) (car (cdr (cdr binding)))))) | |
2769 | ||
2770 | (defun ad-list-access (position list) | |
2771 | (cond ((= position 0) list) | |
2772 | ((= position 1) (list 'cdr list)) | |
2773 | (t (list 'nthcdr position list)))) | |
2774 | ||
2775 | (defun ad-element-access (position list) | |
2776 | (cond ((= position 0) (list 'car list)) | |
2777 | ((= position 1) (` (car (cdr (, list))))) | |
2778 | (t (list 'nth position list)))) | |
2779 | ||
2780 | (defun ad-access-argument (arglist index) | |
2781 | ;;"Tells how to access ARGLIST's actual argument at position INDEX. | |
2782 | ;;For a required/optional arg it simply returns it, if a rest argument has | |
2783 | ;;to be accessed, it returns a list with the index and name." | |
2784 | (let* ((parsed-arglist (ad-parse-arglist arglist)) | |
2785 | (reqopt-args (append (nth 0 parsed-arglist) | |
2786 | (nth 1 parsed-arglist))) | |
2787 | (rest-arg (nth 2 parsed-arglist))) | |
2788 | (cond ((< index (length reqopt-args)) | |
2789 | (nth index reqopt-args)) | |
2790 | (rest-arg | |
2791 | (list (- index (length reqopt-args)) rest-arg))))) | |
2792 | ||
2793 | (defun ad-get-argument (arglist index) | |
2794 | ;;"Returns form to access ARGLIST's actual argument at position INDEX." | |
2795 | (let ((argument-access (ad-access-argument arglist index))) | |
2796 | (cond ((consp argument-access) | |
2797 | (ad-element-access | |
2798 | (car argument-access) (car (cdr argument-access)))) | |
2799 | (argument-access)))) | |
2800 | ||
2801 | (defun ad-set-argument (arglist index value-form) | |
2802 | ;;"Returns form to set ARGLIST's actual arg at INDEX to VALUE-FORM." | |
2803 | (let ((argument-access (ad-access-argument arglist index))) | |
2804 | (cond ((consp argument-access) | |
2805 | ;; should this check whether there actually is something to set? | |
2806 | (` (setcar (, (ad-list-access | |
2807 | (car argument-access) (car (cdr argument-access)))) | |
2808 | (, value-form)))) | |
2809 | (argument-access | |
2810 | (` (setq (, argument-access) (, value-form)))) | |
2811 | (t (error "ad-set-argument: No argument at position %d of `%s'" | |
2812 | index arglist))))) | |
2813 | ||
2814 | (defun ad-get-arguments (arglist index) | |
2815 | ;;"Returns form to access all actual arguments starting at position INDEX." | |
2816 | (let* ((parsed-arglist (ad-parse-arglist arglist)) | |
2817 | (reqopt-args (append (nth 0 parsed-arglist) | |
2818 | (nth 1 parsed-arglist))) | |
2819 | (rest-arg (nth 2 parsed-arglist)) | |
2820 | args-form) | |
2821 | (if (< index (length reqopt-args)) | |
2822 | (setq args-form (` (list (,@ (nthcdr index reqopt-args)))))) | |
2823 | (if rest-arg | |
2824 | (if args-form | |
2825 | (setq args-form (` (nconc (, args-form) (, rest-arg)))) | |
2826 | (setq args-form (ad-list-access (- index (length reqopt-args)) | |
2827 | rest-arg)))) | |
2828 | args-form)) | |
2829 | ||
2830 | (defun ad-set-arguments (arglist index values-form) | |
2831 | ;;"Makes form to assign elements of VALUES-FORM as actual ARGLIST args. | |
2832 | ;;The assignment starts at position INDEX." | |
2833 | (let ((values-index 0) | |
2834 | argument-access set-forms) | |
2835 | (while (setq argument-access (ad-access-argument arglist index)) | |
2836 | (if (symbolp argument-access) | |
2837 | (setq set-forms | |
2838 | (cons (ad-set-argument | |
2839 | arglist index | |
2840 | (ad-element-access values-index 'ad-vAlUeS)) | |
2841 | set-forms)) | |
2842 | (setq set-forms | |
2843 | (cons (if (= (car argument-access) 0) | |
2844 | (list 'setq | |
2845 | (car (cdr argument-access)) | |
2846 | (ad-list-access values-index 'ad-vAlUeS)) | |
2847 | (list 'setcdr | |
2848 | (ad-list-access (1- (car argument-access)) | |
2849 | (car (cdr argument-access))) | |
2850 | (ad-list-access values-index 'ad-vAlUeS))) | |
2851 | set-forms)) | |
2852 | ;; terminate loop | |
2853 | (setq arglist nil)) | |
2854 | (setq index (1+ index)) | |
2855 | (setq values-index (1+ values-index))) | |
2856 | (if (null set-forms) | |
2857 | (error "ad-set-arguments: No argument at position %d of `%s'" | |
2858 | index arglist) | |
2859 | (if (= (length set-forms) 1) | |
2860 | ;; For exactly one set-form we can use values-form directly,... | |
2861 | (ad-substitute-tree | |
2862 | (function (lambda (form) (eq form 'ad-vAlUeS))) | |
2863 | (function (lambda (form) values-form)) | |
2864 | (car set-forms)) | |
2865 | ;; ...if we have more we have to bind it to a variable: | |
2866 | (` (let ((ad-vAlUeS (, values-form))) | |
2867 | (,@ (reverse set-forms)) | |
2868 | ;; work around the old backquote bug: | |
2869 | (, 'ad-vAlUeS))))))) | |
2870 | ||
2871 | (defun ad-insert-argument-access-forms (definition arglist) | |
2872 | ;;"Expands arg-access text macros in DEFINITION according to ARGLIST." | |
2873 | (ad-substitute-tree | |
2874 | (function | |
2875 | (lambda (form) | |
2876 | (or (eq form 'ad-arg-bindings) | |
2877 | (and (memq (car-safe form) | |
2878 | '(ad-get-arg ad-get-args ad-set-arg ad-set-args)) | |
2879 | (integerp (car-safe (cdr form))))))) | |
2880 | (function | |
2881 | (lambda (form) | |
2882 | (if (eq form 'ad-arg-bindings) | |
2883 | (ad-retrieve-args-form arglist) | |
2884 | (let ((accessor (car form)) | |
2885 | (index (car (cdr form))) | |
2886 | (val (car (cdr (ad-insert-argument-access-forms | |
2887 | (cdr form) arglist))))) | |
2888 | (cond ((eq accessor 'ad-get-arg) | |
2889 | (ad-get-argument arglist index)) | |
2890 | ((eq accessor 'ad-set-arg) | |
2891 | (ad-set-argument arglist index val)) | |
2892 | ((eq accessor 'ad-get-args) | |
2893 | (ad-get-arguments arglist index)) | |
2894 | ((eq accessor 'ad-set-args) | |
2895 | (ad-set-arguments arglist index val))))))) | |
2896 | definition)) | |
2897 | ||
2898 | ;; @@@ Mapping argument lists: | |
2899 | ;; =========================== | |
2900 | ;; Here is the problem: | |
2901 | ;; Suppose function foo was called with (foo 1 2 3 4 5), and foo has the | |
2902 | ;; argument list (x y &rest z), and we want to call the function bar which | |
2903 | ;; has argument list (a &rest b) with a combination of x, y and z so that | |
2904 | ;; the effect is just as if we had called (bar 1 2 3 4 5) directly. | |
2905 | ;; The mapping should work for any two argument lists. | |
2906 | ||
2907 | (defun ad-map-arglists (source-arglist target-arglist) | |
6e2f6f45 | 2908 | "Makes `funcall/apply' form to map SOURCE-ARGLIST to TARGET-ARGLIST. |
ee7bf2ad RM |
2909 | The arguments supplied to TARGET-ARGLIST will be taken from SOURCE-ARGLIST just |
2910 | as if they had been supplied to a function with TARGET-ARGLIST directly. | |
2911 | Excess source arguments will be neglected, missing source arguments will be | |
6e2f6f45 RS |
2912 | supplied as nil. Returns a `funcall' or `apply' form with the second element |
2913 | being `function' which has to be replaced by an actual function argument. | |
2914 | Example: `(ad-map-arglists '(a &rest args) '(w x y z))' will return | |
2915 | `(funcall function a (car args) (car (cdr args)) (nth 2 args))'." | |
ee7bf2ad RM |
2916 | (let* ((parsed-source-arglist (ad-parse-arglist source-arglist)) |
2917 | (source-reqopt-args (append (nth 0 parsed-source-arglist) | |
2918 | (nth 1 parsed-source-arglist))) | |
2919 | (source-rest-arg (nth 2 parsed-source-arglist)) | |
2920 | (parsed-target-arglist (ad-parse-arglist target-arglist)) | |
2921 | (target-reqopt-args (append (nth 0 parsed-target-arglist) | |
2922 | (nth 1 parsed-target-arglist))) | |
2923 | (target-rest-arg (nth 2 parsed-target-arglist)) | |
2924 | (need-apply (and source-rest-arg target-rest-arg)) | |
2925 | (target-arg-index -1)) | |
2926 | ;; This produces ``error-proof'' target function calls with the exception | |
2927 | ;; of a case like (&rest a) mapped onto (x &rest y) where the actual args | |
2928 | ;; supplied to A might not be enough to supply the required target arg X | |
2929 | (append (list (if need-apply 'apply 'funcall) 'function) | |
2930 | (cond (need-apply | |
2931 | ;; `apply' can take care of that directly: | |
2932 | (append source-reqopt-args (list source-rest-arg))) | |
2933 | (t (mapcar (function | |
2934 | (lambda (arg) | |
2935 | (setq target-arg-index (1+ target-arg-index)) | |
2936 | (ad-get-argument | |
2937 | source-arglist target-arg-index))) | |
2938 | (append target-reqopt-args | |
2939 | (and target-rest-arg | |
2940 | ;; If we have a rest arg gobble up | |
2941 | ;; remaining source args: | |
2942 | (nthcdr (length target-reqopt-args) | |
2943 | source-reqopt-args))))))))) | |
2944 | ||
2945 | (defun ad-make-mapped-call (source-arglist target-arglist target-function) | |
2946 | ;;"Makes form to call TARGET-FUNCTION with args from SOURCE-ARGLIST." | |
2947 | (let* ((mapped-form (ad-map-arglists source-arglist target-arglist))) | |
2948 | (if (eq (car mapped-form) 'funcall) | |
2949 | (cons target-function (cdr (cdr mapped-form))) | |
2950 | (prog1 mapped-form | |
2951 | (setcar (cdr mapped-form) (list 'quote target-function)))))) | |
2952 | ||
2953 | ;; @@@ Making an advised documentation string: | |
2954 | ;; =========================================== | |
2955 | ;; New policy: The documentation string for an advised function will be built | |
6e2f6f45 | 2956 | ;; at the time the advised `documentation' function is called. This has the |
ee7bf2ad RM |
2957 | ;; following advantages: |
2958 | ;; 1) command-key substitutions will automatically be correct | |
2959 | ;; 2) No wasted string space due to big advised docstrings in caches or | |
2960 | ;; compiled files that contain preactivations | |
2961 | ;; The overall overhead for this should be negligible because people normally | |
2962 | ;; don't lookup documentation for the same function over and over again. | |
2963 | ||
6e2f6f45 | 2964 | (defun ad-make-single-advice-docstring (advice class &optional style) |
ee7bf2ad | 2965 | (let ((advice-docstring (ad-docstring (ad-advice-definition advice)))) |
6e2f6f45 RS |
2966 | (cond ((eq style 'plain) |
2967 | advice-docstring) | |
2968 | ((eq style 'freeze) | |
2969 | (format "Permanent %s-advice `%s':%s%s" | |
2970 | class (ad-advice-name advice) | |
2971 | (if advice-docstring "\n" "") | |
2972 | (or advice-docstring ""))) | |
2973 | (t (format "%s-advice `%s':%s%s" | |
2974 | (capitalize (symbol-name class)) (ad-advice-name advice) | |
2975 | (if advice-docstring "\n" "") | |
2976 | (or advice-docstring "")))))) | |
2977 | ||
2978 | (defun ad-make-advised-docstring (function &optional style) | |
ee7bf2ad RM |
2979 | ;;"Constructs a documentation string for the advised FUNCTION. |
2980 | ;;It concatenates the original documentation with the documentation | |
6e2f6f45 RS |
2981 | ;;strings of the individual pieces of advice which will be formatted |
2982 | ;;according to STYLE. STYLE can be `plain' or `freeze', everything else | |
2983 | ;;will be interpreted as `default'. The order of the advice documentation | |
ee7bf2ad RM |
2984 | ;;strings corresponds to before/around/after and the individual ordering |
2985 | ;;in any of these classes." | |
2986 | (let* ((origdef (ad-real-orig-definition function)) | |
6e2f6f45 | 2987 | (origtype (symbol-name (ad-definition-type origdef))) |
ee7bf2ad | 2988 | (origdoc |
6e2f6f45 RS |
2989 | ;; Retrieve raw doc, key substitution will be taken care of later: |
2990 | (ad-real-documentation origdef t)) | |
2991 | paragraphs advice-docstring) | |
2992 | (if origdoc (setq paragraphs (list origdoc))) | |
2993 | (if (not (eq style 'plain)) | |
2994 | (setq paragraphs (cons (concat "This " origtype " is advised.") | |
2995 | paragraphs))) | |
2996 | (ad-dolist (class ad-advice-classes) | |
2997 | (ad-dolist (advice (ad-get-enabled-advices function class)) | |
2998 | (setq advice-docstring | |
2999 | (ad-make-single-advice-docstring advice class style)) | |
3000 | (if advice-docstring | |
3001 | (setq paragraphs (cons advice-docstring paragraphs))))) | |
3002 | (if paragraphs | |
3003 | ;; separate paragraphs with blank lines: | |
3004 | (mapconcat 'identity (nreverse paragraphs) "\n\n")))) | |
3005 | ||
3006 | (defun ad-make-plain-docstring (function) | |
3007 | (ad-make-advised-docstring function 'plain)) | |
3008 | (defun ad-make-freeze-docstring (function) | |
3009 | (ad-make-advised-docstring function 'freeze)) | |
ee7bf2ad RM |
3010 | |
3011 | ;; @@@ Accessing overriding arglists and interactive forms: | |
3012 | ;; ======================================================== | |
3013 | ||
3014 | (defun ad-advised-arglist (function) | |
3015 | ;;"Finds first defined arglist in FUNCTION's redefining advices." | |
3016 | (ad-dolist (advice (append (ad-get-enabled-advices function 'before) | |
3017 | (ad-get-enabled-advices function 'around) | |
3018 | (ad-get-enabled-advices function 'after))) | |
3019 | (let ((arglist (ad-arglist (ad-advice-definition advice)))) | |
3020 | (if arglist | |
3021 | ;; We found the first one, use it: | |
3022 | (ad-do-return arglist))))) | |
3023 | ||
3024 | (defun ad-advised-interactive-form (function) | |
3025 | ;;"Finds first interactive form in FUNCTION's redefining advices." | |
3026 | (ad-dolist (advice (append (ad-get-enabled-advices function 'before) | |
3027 | (ad-get-enabled-advices function 'around) | |
3028 | (ad-get-enabled-advices function 'after))) | |
3029 | (let ((interactive-form | |
3030 | (ad-interactive-form (ad-advice-definition advice)))) | |
3031 | (if interactive-form | |
3032 | ;; We found the first one, use it: | |
3033 | (ad-do-return interactive-form))))) | |
3034 | ||
3035 | ;; @@@ Putting it all together: | |
3036 | ;; ============================ | |
3037 | ||
3038 | (defun ad-make-advised-definition (function) | |
3039 | ;;"Generates an advised definition of FUNCTION from its advice info." | |
3040 | (if (and (ad-is-advised function) | |
3041 | (ad-has-redefining-advice function)) | |
3042 | (let* ((origdef (ad-real-orig-definition function)) | |
3043 | (origname (ad-get-advice-info-field function 'origname)) | |
3044 | (orig-interactive-p (ad-interactive-p origdef)) | |
3045 | (orig-subr-p (ad-subr-p origdef)) | |
3046 | (orig-special-form-p (ad-special-form-p origdef)) | |
3047 | (orig-macro-p (ad-macro-p origdef)) | |
3048 | ;; Construct the individual pieces that we need for assembly: | |
3049 | (orig-arglist (ad-arglist origdef function)) | |
3050 | (advised-arglist (or (ad-advised-arglist function) | |
3051 | orig-arglist)) | |
3052 | (advised-interactive-form (ad-advised-interactive-form function)) | |
3053 | (interactive-form | |
3054 | (cond (orig-macro-p nil) | |
3055 | (advised-interactive-form) | |
3056 | ((ad-interactive-form origdef)) | |
3057 | ;; Otherwise we must have a subr: make it interactive if | |
3058 | ;; we have to and initialize required arguments in case | |
3059 | ;; it is called interactively: | |
3060 | (orig-interactive-p | |
3061 | (let ((reqargs (car (ad-parse-arglist advised-arglist)))) | |
3062 | (if reqargs | |
3063 | (` (interactive | |
3064 | '(, (make-list (length reqargs) nil)))) | |
3065 | '(interactive)))))) | |
3066 | (orig-form | |
3067 | (cond ((or orig-special-form-p orig-macro-p) | |
3068 | ;; Special forms and macros will be advised into macros. | |
3069 | ;; The trick is to construct an expansion for the advised | |
3070 | ;; macro that does the correct thing when it gets eval'ed. | |
3071 | ;; For macros we'll just use the expansion of the original | |
3072 | ;; macro and return that. This way compiled advised macros | |
3073 | ;; will be expanded into something useful. Note that after | |
3074 | ;; advices have full control over whether they want to | |
3075 | ;; evaluate the expansion (the value of `ad-return-value') | |
3076 | ;; at macro expansion time or not. For special forms there | |
3077 | ;; is no solution that interacts reasonably with the | |
3078 | ;; compiler, hence we just evaluate the original at macro | |
3079 | ;; expansion time and return the result. The moral of that | |
3080 | ;; is that one should always deactivate advised special | |
3081 | ;; forms before one byte-compiles a file. | |
3082 | (` ((, (if orig-macro-p | |
3083 | 'macroexpand | |
3084 | 'eval)) | |
3085 | (cons '(, origname) | |
3086 | (, (ad-get-arguments advised-arglist 0)))))) | |
3087 | ((and orig-subr-p | |
3088 | orig-interactive-p | |
3089 | (not advised-interactive-form)) | |
3090 | ;; Check whether we were called interactively | |
3091 | ;; in order to do proper prompting: | |
3092 | (` (if (interactive-p) | |
3093 | (call-interactively '(, origname)) | |
3094 | (, (ad-make-mapped-call | |
3095 | orig-arglist advised-arglist origname))))) | |
3096 | ;; And now for normal functions and non-interactive subrs | |
3097 | ;; (or subrs whose interactive behavior was advised): | |
3098 | (t (ad-make-mapped-call | |
3099 | advised-arglist orig-arglist origname))))) | |
3100 | ||
3101 | ;; Finally, build the sucker: | |
3102 | (ad-assemble-advised-definition | |
3103 | (cond (orig-macro-p 'macro) | |
3104 | (orig-special-form-p 'special-form) | |
3105 | (t 'function)) | |
3106 | advised-arglist | |
3107 | (ad-make-advised-definition-docstring function) | |
3108 | interactive-form | |
3109 | orig-form | |
3110 | (ad-get-enabled-advices function 'before) | |
3111 | (ad-get-enabled-advices function 'around) | |
3112 | (ad-get-enabled-advices function 'after))))) | |
3113 | ||
3114 | (defun ad-assemble-advised-definition | |
3115 | (type args docstring interactive orig &optional befores arounds afters) | |
3116 | ||
3117 | ;;"Assembles an original and its advices into an advised function. | |
3118 | ;;It constructs a function or macro definition according to TYPE which has to | |
6e2f6f45 RS |
3119 | ;;be either `macro', `function' or `special-form'. ARGS is the argument list |
3120 | ;;that has to be used, DOCSTRING if non-nil defines the documentation of the | |
3121 | ;;definition, INTERACTIVE if non-nil is the interactive form to be used, | |
ee7bf2ad RM |
3122 | ;;ORIG is a form that calls the body of the original unadvised function, |
3123 | ;;and BEFORES, AROUNDS and AFTERS are the lists of advices with which ORIG | |
6e2f6f45 | 3124 | ;;should be modified. The assembled function will be returned." |
ee7bf2ad RM |
3125 | |
3126 | (let (before-forms around-form around-form-protected after-forms definition) | |
3127 | (ad-dolist (advice befores) | |
3128 | (cond ((and (ad-advice-protected advice) | |
3129 | before-forms) | |
3130 | (setq before-forms | |
3131 | (` ((unwind-protect | |
3132 | (, (ad-prognify before-forms)) | |
3133 | (,@ (ad-body-forms | |
3134 | (ad-advice-definition advice)))))))) | |
3135 | (t (setq before-forms | |
3136 | (append before-forms | |
3137 | (ad-body-forms (ad-advice-definition advice))))))) | |
3138 | ||
3139 | (setq around-form (` (setq ad-return-value (, orig)))) | |
3140 | (ad-dolist (advice (reverse arounds)) | |
3141 | ;; If any of the around advices is protected then we | |
3142 | ;; protect the complete around advice onion: | |
3143 | (if (ad-advice-protected advice) | |
3144 | (setq around-form-protected t)) | |
3145 | (setq around-form | |
3146 | (ad-substitute-tree | |
3147 | (function (lambda (form) (eq form 'ad-do-it))) | |
3148 | (function (lambda (form) around-form)) | |
3149 | (ad-prognify (ad-body-forms (ad-advice-definition advice)))))) | |
3150 | ||
3151 | (setq after-forms | |
3152 | (if (and around-form-protected before-forms) | |
3153 | (` ((unwind-protect | |
3154 | (, (ad-prognify before-forms)) | |
3155 | (, around-form)))) | |
3156 | (append before-forms (list around-form)))) | |
3157 | (ad-dolist (advice afters) | |
3158 | (cond ((and (ad-advice-protected advice) | |
3159 | after-forms) | |
3160 | (setq after-forms | |
3161 | (` ((unwind-protect | |
3162 | (, (ad-prognify after-forms)) | |
3163 | (,@ (ad-body-forms | |
3164 | (ad-advice-definition advice)))))))) | |
3165 | (t (setq after-forms | |
3166 | (append after-forms | |
3167 | (ad-body-forms (ad-advice-definition advice))))))) | |
3168 | ||
3169 | (setq definition | |
3170 | (` ((,@ (if (memq type '(macro special-form)) '(macro))) | |
3171 | lambda | |
3172 | (, args) | |
3173 | (,@ (if docstring (list docstring))) | |
3174 | (,@ (if interactive (list interactive))) | |
3175 | (let (ad-return-value) | |
3176 | (,@ after-forms) | |
3177 | (, (if (eq type 'special-form) | |
3178 | '(list 'quote ad-return-value) | |
3179 | 'ad-return-value)))))) | |
3180 | ||
3181 | (ad-insert-argument-access-forms definition args))) | |
3182 | ||
3183 | ;; This is needed for activation/deactivation hooks: | |
3184 | (defun ad-make-hook-form (function hook-name) | |
3185 | ;;"Makes hook-form from FUNCTION's advice bodies in class HOOK-NAME." | |
3186 | (let ((hook-forms | |
3187 | (mapcar (function (lambda (advice) | |
3188 | (ad-body-forms (ad-advice-definition advice)))) | |
3189 | (ad-get-enabled-advices function hook-name)))) | |
3190 | (if hook-forms | |
3191 | (ad-prognify (apply 'append hook-forms))))) | |
3192 | ||
3193 | ||
3194 | ;; @@ Caching: | |
3195 | ;; =========== | |
3196 | ;; Generating an advised definition of a function is moderately expensive, | |
3197 | ;; hence, it makes sense to cache it so we can reuse it in appropriate | |
3198 | ;; circumstances. Of course, it only makes sense to reuse a cached | |
3199 | ;; definition if the current advice and function definition state is the | |
3200 | ;; same as it was at the time when the cached definition was generated. | |
3201 | ;; For that purpose we associate every cache with an id so we can verify | |
6e2f6f45 | 3202 | ;; if it is still valid at a certain point in time. This id mechanism |
ee7bf2ad RM |
3203 | ;; makes it possible to preactivate advised functions, write the compiled |
3204 | ;; advised definitions to a file and reuse them during the actual | |
3205 | ;; activation without having to risk that the resulting definition will be | |
3206 | ;; incorrect, well, almost. | |
3207 | ;; | |
3208 | ;; A cache id is a list with six elements: | |
3209 | ;; 1) the list of names of enabled before advices | |
3210 | ;; 2) the list of names of enabled around advices | |
3211 | ;; 3) the list of names of enabled after advices | |
3212 | ;; 4) the type of the original function (macro, subr, etc.) | |
3213 | ;; 5) the arglist of the original definition (or t if it was equal to the | |
3214 | ;; arglist of the cached definition) | |
3215 | ;; 6) t if the interactive form of the original definition was equal to the | |
3216 | ;; interactive form of the cached definition | |
3217 | ;; | |
3218 | ;; Here's how a cache can get invalidated or be incorrect: | |
3219 | ;; A) a piece of advice used in the cache gets redefined | |
3220 | ;; B) the current list of enabled advices is different from the ones used | |
3221 | ;; for the cache | |
3222 | ;; C) the type of the original function changed, e.g., a function became a | |
3223 | ;; macro, or a subr became a function | |
3224 | ;; D) the arglist of the original function changed | |
3225 | ;; E) the interactive form of the original function changed | |
3226 | ;; F) a piece of advice used in the cache got redefined before the | |
3227 | ;; defadvice with the cached definition got loaded: This is a PROBLEM! | |
3228 | ;; | |
6e2f6f45 | 3229 | ;; Cases A and B are the normal ones. A is taken care of by `ad-add-advice' |
ee7bf2ad RM |
3230 | ;; which clears the cache in such a case, B is easily checked during |
3231 | ;; verification at activation time. | |
3232 | ;; | |
3233 | ;; Cases C, D and E have to be considered if one is slightly paranoid, i.e., | |
3234 | ;; if one considers the case that the original function could be different | |
3235 | ;; from the one available at caching time (e.g., for forward advice of | |
3236 | ;; functions that get redefined by some packages - such as `eval-region' gets | |
6e2f6f45 RS |
3237 | ;; redefined by edebug). All these cases can be easily checked during |
3238 | ;; verification. Element 4 of the id lets one check case C, element 5 takes | |
ee7bf2ad RM |
3239 | ;; care of case D (using t in the equality case saves some space, because the |
3240 | ;; arglist can be recovered at validation time from the cached definition), | |
3241 | ;; and element 6 takes care of case E which is only a problem if the original | |
3242 | ;; was actually a function whose interactive form was not overridden by a | |
3243 | ;; piece of advice. | |
3244 | ;; | |
3245 | ;; Case F is the only one which will lead to an incorrect advised function. | |
3246 | ;; There is no way to avoid this without storing the complete advice definition | |
3247 | ;; in the cache-id which is not feasible. | |
3248 | ;; | |
3249 | ;; The cache-id of a typical advised function with one piece of advice and | |
3250 | ;; no arglist redefinition takes 7 conses which is a small price to pay for | |
6e2f6f45 | 3251 | ;; the added efficiency. The validation itself is also pretty cheap, certainly |
ee7bf2ad RM |
3252 | ;; a lot cheaper than reconstructing an advised definition. |
3253 | ||
3254 | (defmacro ad-get-cache-definition (function) | |
3255 | (` (car (ad-get-advice-info-field (, function) 'cache)))) | |
3256 | ||
3257 | (defmacro ad-get-cache-id (function) | |
3258 | (` (cdr (ad-get-advice-info-field (, function) 'cache)))) | |
3259 | ||
3260 | (defmacro ad-set-cache (function definition id) | |
3261 | (` (ad-set-advice-info-field | |
3262 | (, function) 'cache (cons (, definition) (, id))))) | |
3263 | ||
3264 | (defun ad-clear-cache (function) | |
3265 | "Clears a previously cached advised definition of FUNCTION. | |
3266 | Clear the cache if you want to force `ad-activate' to construct a new | |
3267 | advised definition from scratch." | |
3268 | (interactive | |
3269 | (list (ad-read-advised-function "Clear cached definition of: "))) | |
3270 | (ad-set-advice-info-field function 'cache nil)) | |
3271 | ||
3272 | (defun ad-make-cache-id (function) | |
3273 | ;;"Generates an identifying image of the current advices of FUNCTION." | |
3274 | (let ((original-definition (ad-real-orig-definition function)) | |
3275 | (cached-definition (ad-get-cache-definition function))) | |
3276 | (list (mapcar (function (lambda (advice) (ad-advice-name advice))) | |
3277 | (ad-get-enabled-advices function 'before)) | |
3278 | (mapcar (function (lambda (advice) (ad-advice-name advice))) | |
3279 | (ad-get-enabled-advices function 'around)) | |
3280 | (mapcar (function (lambda (advice) (ad-advice-name advice))) | |
3281 | (ad-get-enabled-advices function 'after)) | |
3282 | (ad-definition-type original-definition) | |
3283 | (if (equal (ad-arglist original-definition function) | |
3284 | (ad-arglist cached-definition)) | |
3285 | t | |
3286 | (ad-arglist original-definition function)) | |
3287 | (if (eq (ad-definition-type original-definition) 'function) | |
3288 | (equal (ad-interactive-form original-definition) | |
3289 | (ad-interactive-form cached-definition)))))) | |
3290 | ||
3291 | (defun ad-get-cache-class-id (function class) | |
3292 | ;;"Returns the part of FUNCTION's cache id that identifies CLASS." | |
3293 | (let ((cache-id (ad-get-cache-id function))) | |
3294 | (if (eq class 'before) | |
3295 | (car cache-id) | |
3296 | (if (eq class 'around) | |
3297 | (nth 1 cache-id) | |
3298 | (nth 2 cache-id))))) | |
3299 | ||
3300 | (defun ad-verify-cache-class-id (cache-class-id advices) | |
3301 | (ad-dolist (advice advices (null cache-class-id)) | |
3302 | (if (ad-advice-enabled advice) | |
3303 | (if (eq (car cache-class-id) (ad-advice-name advice)) | |
3304 | (setq cache-class-id (cdr cache-class-id)) | |
3305 | (ad-do-return nil))))) | |
3306 | ||
3307 | ;; There should be a way to monitor if and why a cache verification failed | |
3308 | ;; in order to determine whether a certain preactivation could be used or | |
6e2f6f45 RS |
3309 | ;; not. Right now the only way to find out is to trace |
3310 | ;; `ad-cache-id-verification-code'. The code it returns indicates where the | |
3311 | ;; verification failed. Tracing `ad-verify-cache-class-id' might provide | |
ee7bf2ad RM |
3312 | ;; some additional useful information. |
3313 | ||
3314 | (defun ad-cache-id-verification-code (function) | |
3315 | (let ((cache-id (ad-get-cache-id function)) | |
3316 | (code 'before-advice-mismatch)) | |
3317 | (and (ad-verify-cache-class-id | |
3318 | (car cache-id) (ad-get-advice-info-field function 'before)) | |
3319 | (setq code 'around-advice-mismatch) | |
3320 | (ad-verify-cache-class-id | |
3321 | (nth 1 cache-id) (ad-get-advice-info-field function 'around)) | |
3322 | (setq code 'after-advice-mismatch) | |
3323 | (ad-verify-cache-class-id | |
3324 | (nth 2 cache-id) (ad-get-advice-info-field function 'after)) | |
3325 | (setq code 'definition-type-mismatch) | |
3326 | (let ((original-definition (ad-real-orig-definition function)) | |
3327 | (cached-definition (ad-get-cache-definition function))) | |
3328 | (and (eq (nth 3 cache-id) (ad-definition-type original-definition)) | |
3329 | (setq code 'arglist-mismatch) | |
3330 | (equal (if (eq (nth 4 cache-id) t) | |
3331 | (ad-arglist original-definition function) | |
3332 | (nth 4 cache-id) ) | |
3333 | (ad-arglist cached-definition)) | |
3334 | (setq code 'interactive-form-mismatch) | |
3335 | (or (null (nth 5 cache-id)) | |
3336 | (equal (ad-interactive-form original-definition) | |
3337 | (ad-interactive-form cached-definition))) | |
3338 | (setq code 'verified)))) | |
3339 | code)) | |
3340 | ||
3341 | (defun ad-verify-cache-id (function) | |
3342 | ;;"True if FUNCTION's cache-id is compatible with its current advices." | |
3343 | (eq (ad-cache-id-verification-code function) 'verified)) | |
3344 | ||
3345 | ||
3346 | ;; @@ Preactivation: | |
3347 | ;; ================= | |
3348 | ;; Preactivation can be used to generate compiled advised definitions | |
3349 | ;; at compile time without having to give up the dynamic runtime flexibility | |
6e2f6f45 | 3350 | ;; of the advice mechanism. Preactivation is a special feature of `defadvice', |
ee7bf2ad RM |
3351 | ;; it involves the following steps: |
3352 | ;; - remembering the function's current state (definition and advice-info) | |
3353 | ;; - advising it with the defined piece of advice | |
3354 | ;; - clearing its cache | |
3355 | ;; - generating an interpreted advised definition by activating it, this will | |
3356 | ;; make use of all its current active advice and its current definition | |
3357 | ;; - saving the so generated cached definition and id | |
3358 | ;; - resetting the function's advice and definition state to what it was | |
3359 | ;; before the preactivation | |
3360 | ;; - Returning the saved definition and its id to be used in the expansion of | |
3361 | ;; `defadvice' to assign it as an initial cache, hence it will be compiled | |
6e2f6f45 | 3362 | ;; at time the `defadvice' gets compiled. |
ee7bf2ad RM |
3363 | ;; Naturally, for preactivation to be effective it has to be applied/compiled |
3364 | ;; at the right time, i.e., when the current state of advices and function | |
6e2f6f45 | 3365 | ;; definition exactly reflects the state at activation time. Should that not |
ee7bf2ad RM |
3366 | ;; be the case, the precompiled definition will just be discarded and a new |
3367 | ;; advised definition will be generated. | |
3368 | ||
3369 | (defun ad-preactivate-advice (function advice class position) | |
3370 | ;;"Preactivates FUNCTION and returns the constructed cache." | |
3371 | (let* ((function-defined-p (fboundp function)) | |
3372 | (old-definition | |
3373 | (if function-defined-p | |
3374 | (symbol-function function))) | |
3375 | (old-advice-info (ad-copy-advice-info function)) | |
3376 | (ad-advised-functions ad-advised-functions)) | |
3377 | (unwind-protect | |
3378 | (progn | |
3379 | (ad-add-advice function advice class position) | |
3380 | (ad-enable-advice function class (ad-advice-name advice)) | |
3381 | (ad-clear-cache function) | |
fabaa9b5 | 3382 | (ad-activate-on function -1) |
ee7bf2ad RM |
3383 | (if (and (ad-is-active function) |
3384 | (ad-get-cache-definition function)) | |
3385 | (list (ad-get-cache-definition function) | |
3386 | (ad-get-cache-id function)))) | |
3387 | (ad-set-advice-info function old-advice-info) | |
3388 | ;; Don't `fset' function to nil if it was previously unbound: | |
3389 | (if function-defined-p | |
fabaa9b5 | 3390 | (ad-safe-fset function old-definition) |
ee7bf2ad RM |
3391 | (fmakunbound function))))) |
3392 | ||
fabaa9b5 RS |
3393 | |
3394 | ;; @@ Freezing: | |
3395 | ;; ============ | |
3396 | ;; Freezing transforms a `defadvice' into a redefining `defun/defmacro' | |
3397 | ;; for the advised function without keeping any advice information. This | |
3398 | ;; feature was jwz's idea: It generates a dumpable function definition | |
3399 | ;; whose documentation can be written to the DOC file, and the generated | |
3400 | ;; code does not need any Advice runtime support. Of course, frozen advices | |
3401 | ;; cannot be undone. | |
3402 | ||
3403 | ;; Freezing only considers the advice of the particular `defadvice', other | |
3404 | ;; already existing advices for the same function will be ignored. To ensure | |
3405 | ;; proper interaction when an already advised function gets redefined with | |
3406 | ;; a frozen advice, frozen advices always use the actual original definition | |
3407 | ;; of the function, i.e., they are always at the core of the onion. E.g., if | |
3408 | ;; an already advised function gets redefined with a frozen advice and then | |
3409 | ;; unadvised, the frozen advice remains as the new definition of the function. | |
3410 | ||
3411 | ;; While multiple freeze advices for a single function or freeze-advising | |
3412 | ;; of an already advised function are possible, they are better avoided, | |
3413 | ;; because definition/compile/load ordering is relevant, and it becomes | |
3414 | ;; incomprehensible pretty quickly. | |
3415 | ||
3416 | (defun ad-make-freeze-definition (function advice class position) | |
3417 | (if (not (ad-has-proper-definition function)) | |
3418 | (error | |
3419 | "ad-make-freeze-definition: `%s' is not yet defined" | |
3420 | function)) | |
3421 | (let* ((name (ad-advice-name advice)) | |
3422 | ;; With a unique origname we can have multiple freeze advices | |
3423 | ;; for the same function, each overloading the previous one: | |
3424 | (unique-origname | |
3425 | (intern (format "%s-%s-%s" (ad-make-origname function) class name))) | |
3426 | (orig-definition | |
3427 | ;; If FUNCTION is already advised, we'll use its current origdef | |
3428 | ;; as the original definition of the frozen advice: | |
3429 | (or (ad-get-orig-definition function) | |
3430 | (symbol-function function))) | |
3431 | (old-advice-info | |
3432 | (if (ad-is-advised function) | |
3433 | (ad-copy-advice-info function))) | |
3434 | (real-docstring-fn | |
3435 | (symbol-function 'ad-make-advised-definition-docstring)) | |
3436 | (real-origname-fn | |
3437 | (symbol-function 'ad-make-origname)) | |
3438 | (frozen-definition | |
3439 | (unwind-protect | |
3440 | (progn | |
3441 | ;; Make sure we construct a proper docstring: | |
3442 | (ad-safe-fset 'ad-make-advised-definition-docstring | |
3443 | 'ad-make-freeze-docstring) | |
3444 | ;; Make sure `unique-origname' is used as the origname: | |
3445 | (ad-safe-fset 'ad-make-origname '(lambda (x) unique-origname)) | |
3446 | ;; No we reset all current advice information to nil and | |
3447 | ;; generate an advised definition that's solely determined | |
3448 | ;; by ADVICE and the current origdef of FUNCTION: | |
3449 | (ad-set-advice-info function nil) | |
3450 | (ad-add-advice function advice class position) | |
3451 | ;; The following will provide proper real docstrings as | |
3452 | ;; well as a definition that will make the compiler happy: | |
3453 | (ad-set-orig-definition function orig-definition) | |
3454 | (ad-make-advised-definition function)) | |
3455 | ;; Restore the old advice state: | |
3456 | (ad-set-advice-info function old-advice-info) | |
3457 | ;; Restore functions: | |
3458 | (ad-safe-fset | |
3459 | 'ad-make-advised-definition-docstring real-docstring-fn) | |
3460 | (ad-safe-fset 'ad-make-origname real-origname-fn)))) | |
3461 | (if frozen-definition | |
3462 | (let* ((macro-p (ad-macro-p frozen-definition)) | |
3463 | (body (cdr (if macro-p | |
3464 | (ad-lambdafy frozen-definition) | |
3465 | frozen-definition)))) | |
3466 | (` (progn | |
3467 | (if (not (fboundp '(, unique-origname))) | |
3468 | (fset '(, unique-origname) | |
3469 | ;; avoid infinite recursion in case the function | |
3470 | ;; we want to freeze is already advised: | |
3471 | (or (ad-get-orig-definition '(, function)) | |
3472 | (symbol-function '(, function))))) | |
3473 | ((, (if macro-p 'defmacro 'defun)) | |
3474 | (, function) | |
3475 | (,@ body)))))))) | |
3476 | ||
3477 | ||
3478 | ;; @@ Activation and definition handling: | |
3479 | ;; ====================================== | |
3480 | ||
3481 | (defun ad-should-compile (function compile) | |
3482 | ;;"Returns non-nil if the advised FUNCTION should be compiled. | |
3483 | ;;If COMPILE is non-nil and not a negative number then it returns t. | |
3484 | ;;If COMPILE is a negative number then it returns nil. | |
3485 | ;;If COMPILE is nil then the result depends on the value of | |
3486 | ;;`ad-default-compilation-action' (which see)." | |
3487 | (if (integerp compile) | |
3488 | (>= compile 0) | |
3489 | (if compile | |
3490 | compile | |
3491 | (cond ((eq ad-default-compilation-action 'never) | |
3492 | nil) | |
3493 | ((eq ad-default-compilation-action 'always) | |
3494 | t) | |
3495 | ((eq ad-default-compilation-action 'like-original) | |
3496 | (or (ad-subr-p (ad-get-orig-definition function)) | |
3497 | (ad-compiled-p (ad-get-orig-definition function)))) | |
3498 | ;; everything else means `maybe': | |
3499 | (t (featurep 'byte-compile)))))) | |
3500 | ||
ee7bf2ad RM |
3501 | (defun ad-activate-advised-definition (function compile) |
3502 | ;;"Redefines FUNCTION with its advised definition from cache or scratch. | |
fabaa9b5 RS |
3503 | ;;The resulting FUNCTION will be compiled if `ad-should-compile' returns t. |
3504 | ;;The current definition and its cache-id will be put into the cache." | |
ee7bf2ad RM |
3505 | (let ((verified-cached-definition |
3506 | (if (ad-verify-cache-id function) | |
3507 | (ad-get-cache-definition function)))) | |
fabaa9b5 | 3508 | (ad-safe-fset function |
ee7bf2ad RM |
3509 | (or verified-cached-definition |
3510 | (ad-make-advised-definition function))) | |
fabaa9b5 RS |
3511 | (if (ad-should-compile function compile) |
3512 | (ad-compile-function function)) | |
ee7bf2ad RM |
3513 | (if verified-cached-definition |
3514 | (if (not (eq verified-cached-definition (symbol-function function))) | |
3515 | ;; we must have compiled, cache the compiled definition: | |
3516 | (ad-set-cache | |
3517 | function (symbol-function function) (ad-get-cache-id function))) | |
3518 | ;; We created a new advised definition, cache it with a proper id: | |
3519 | (ad-clear-cache function) | |
3520 | ;; ad-make-cache-id needs the new cached definition: | |
3521 | (ad-set-cache function (symbol-function function) nil) | |
3522 | (ad-set-cache | |
3523 | function (symbol-function function) (ad-make-cache-id function))))) | |
3524 | ||
3525 | (defun ad-handle-definition (function) | |
3526 | "Handles re/definition of an advised FUNCTION during de/activation. | |
3527 | If FUNCTION does not have an original definition associated with it and | |
3528 | the current definition is usable, then it will be stored as FUNCTION's | |
6e2f6f45 RS |
3529 | original definition. If no current definition is available (even in the |
3530 | case of undefinition) nothing will be done. In the case of redefinition | |
ee7bf2ad | 3531 | the action taken depends on the value of `ad-redefinition-action' (which |
6e2f6f45 | 3532 | see). Redefinition occurs when FUNCTION already has an original definition |
ee7bf2ad | 3533 | associated with it but got redefined with a new definition and then |
6e2f6f45 | 3534 | de/activated. If you do not like the current redefinition action change |
ee7bf2ad RM |
3535 | the value of `ad-redefinition-action' and de/activate again." |
3536 | (let ((original-definition (ad-get-orig-definition function)) | |
3537 | (current-definition (if (ad-real-definition function) | |
3538 | (symbol-function function)))) | |
3539 | (if original-definition | |
3540 | (if current-definition | |
3541 | (if (and (not (eq current-definition original-definition)) | |
3542 | ;; Redefinition with an advised definition from a | |
3543 | ;; different function won't count as such: | |
3544 | (not (ad-advised-definition-p current-definition))) | |
3545 | ;; we have a redefinition: | |
3546 | (if (not (memq ad-redefinition-action '(accept discard warn))) | |
3547 | (error "ad-handle-definition (see its doc): `%s' %s" | |
3548 | function "illegally redefined") | |
3549 | (if (eq ad-redefinition-action 'discard) | |
fabaa9b5 | 3550 | (ad-safe-fset function original-definition) |
ee7bf2ad RM |
3551 | (ad-set-orig-definition function current-definition) |
3552 | (if (eq ad-redefinition-action 'warn) | |
3553 | (message "ad-handle-definition: `%s' got redefined" | |
3554 | function)))) | |
3555 | ;; either advised def or correct original is in place: | |
3556 | nil) | |
3557 | ;; we have an undefinition, ignore it: | |
3558 | nil) | |
3559 | (if current-definition | |
3560 | ;; we have a first definition, save it as original: | |
3561 | (ad-set-orig-definition function current-definition) | |
3562 | ;; we don't have anything noteworthy: | |
3563 | nil)))) | |
3564 | ||
3565 | ||
3566 | ;; @@ The top-level advice interface: | |
3567 | ;; ================================== | |
3568 | ||
fabaa9b5 | 3569 | (defun ad-activate-on (function &optional compile) |
ee7bf2ad RM |
3570 | "Activates all the advice information of an advised FUNCTION. |
3571 | If FUNCTION has a proper original definition then an advised | |
3572 | definition will be generated from FUNCTION's advice info and the | |
6e2f6f45 | 3573 | definition of FUNCTION will be replaced with it. If a previously |
fabaa9b5 RS |
3574 | cached advised definition was available, it will be used. |
3575 | The optional COMPILE argument determines whether the resulting function | |
3576 | or a compilable cached definition will be compiled. If it is negative | |
3577 | no compilation will be performed, if it is positive or otherwise non-nil | |
3578 | the resulting function will be compiled, if it is nil the behavior depends | |
3579 | on the value of `ad-default-compilation-action' (which see). | |
3580 | Activation of an advised function that has an advice info but no actual | |
3581 | pieces of advice is equivalent to a call to `ad-unadvise'. Activation of | |
3582 | an advised function that has actual pieces of advice but none of them are | |
3583 | enabled is equivalent to a call to `ad-deactivate'. The current advised | |
ee7bf2ad RM |
3584 | definition will always be cached for later usage." |
3585 | (interactive | |
3586 | (list (ad-read-advised-function "Activate advice of: ") | |
3587 | current-prefix-arg)) | |
fabaa9b5 RS |
3588 | (if ad-activate-on-top-level |
3589 | ;; avoid recursive calls to `ad-activate-on': | |
3590 | (ad-with-auto-activation-disabled | |
3591 | (if (not (ad-is-advised function)) | |
3592 | (error "ad-activate: `%s' is not advised" function) | |
3593 | (ad-handle-definition function) | |
3594 | ;; Just return for forward advised and not yet defined functions: | |
3595 | (if (ad-get-orig-definition function) | |
3596 | (if (not (ad-has-any-advice function)) | |
3597 | (ad-unadvise function) | |
3598 | ;; Otherwise activate the advice: | |
3599 | (cond ((ad-has-redefining-advice function) | |
3600 | (ad-activate-advised-definition function compile) | |
3601 | (ad-set-advice-info-field function 'active t) | |
3602 | (eval (ad-make-hook-form function 'activation)) | |
3603 | function) | |
3604 | ;; Here we are if we have all disabled advices: | |
3605 | (t (ad-deactivate function))))))))) | |
ee7bf2ad RM |
3606 | |
3607 | (defun ad-deactivate (function) | |
3608 | "Deactivates the advice of an actively advised FUNCTION. | |
3609 | If FUNCTION has a proper original definition, then the current | |
6e2f6f45 | 3610 | definition of FUNCTION will be replaced with it. All the advice |
ee7bf2ad RM |
3611 | information will still be available so it can be activated again with |
3612 | a call to `ad-activate'." | |
3613 | (interactive | |
3614 | (list (ad-read-advised-function "Deactivate advice of: " 'ad-is-active))) | |
3615 | (if (not (ad-is-advised function)) | |
3616 | (error "ad-deactivate: `%s' is not advised" function) | |
3617 | (cond ((ad-is-active function) | |
3618 | (ad-handle-definition function) | |
3619 | (if (not (ad-get-orig-definition function)) | |
3620 | (error "ad-deactivate: `%s' has no original definition" | |
3621 | function) | |
fabaa9b5 | 3622 | (ad-safe-fset function (ad-get-orig-definition function)) |
ee7bf2ad RM |
3623 | (ad-set-advice-info-field function 'active nil) |
3624 | (eval (ad-make-hook-form function 'deactivation)) | |
3625 | function))))) | |
3626 | ||
3627 | (defun ad-update (function &optional compile) | |
3628 | "Update the advised definition of FUNCTION if its advice is active. | |
fabaa9b5 | 3629 | See `ad-activate-on' for documentation on the optional COMPILE argument." |
ee7bf2ad RM |
3630 | (interactive |
3631 | (list (ad-read-advised-function | |
3632 | "Update advised definition of: " 'ad-is-active))) | |
3633 | (if (ad-is-active function) | |
fabaa9b5 | 3634 | (ad-activate-on function compile))) |
ee7bf2ad RM |
3635 | |
3636 | (defun ad-unadvise (function) | |
3637 | "Deactivates FUNCTION and then removes all its advice information. | |
3638 | If FUNCTION was not advised this will be a noop." | |
3639 | (interactive | |
3640 | (list (ad-read-advised-function "Unadvise function: "))) | |
3641 | (cond ((ad-is-advised function) | |
3642 | (if (ad-is-active function) | |
3643 | (ad-deactivate function)) | |
3644 | (ad-clear-orig-definition function) | |
3645 | (ad-set-advice-info function nil) | |
3646 | (ad-pop-advised-function function)))) | |
3647 | ||
3648 | (defun ad-recover (function) | |
3649 | "Tries to recover FUNCTION's original definition and unadvises it. | |
3650 | This is more low-level than `ad-unadvise' because it does not do any | |
3651 | deactivation which might run hooks and get into other trouble. | |
3652 | Use in emergencies." | |
3653 | ;; Use more primitive interactive behavior here: Accept any symbol that's | |
3654 | ;; currently defined in obarray, not necessarily with a function definition: | |
3655 | (interactive | |
3656 | (list (intern | |
3657 | (completing-read "Recover advised function: " obarray nil t)))) | |
3658 | (cond ((ad-is-advised function) | |
3659 | (cond ((ad-get-orig-definition function) | |
fabaa9b5 | 3660 | (ad-safe-fset function (ad-get-orig-definition function)) |
ee7bf2ad RM |
3661 | (ad-clear-orig-definition function))) |
3662 | (ad-set-advice-info function nil) | |
3663 | (ad-pop-advised-function function)))) | |
3664 | ||
3665 | (defun ad-activate-regexp (regexp &optional compile) | |
3666 | "Activates functions with an advice name containing a REGEXP match. | |
fabaa9b5 | 3667 | See `ad-activate-on' for documentation on the optional COMPILE argument." |
ee7bf2ad RM |
3668 | (interactive |
3669 | (list (ad-read-regexp "Activate via advice regexp: ") | |
3670 | current-prefix-arg)) | |
3671 | (ad-do-advised-functions (function) | |
3672 | (if (ad-find-some-advice function 'any regexp) | |
fabaa9b5 | 3673 | (ad-activate-on function compile)))) |
ee7bf2ad RM |
3674 | |
3675 | (defun ad-deactivate-regexp (regexp) | |
3676 | "Deactivates functions with an advice name containing REGEXP match." | |
3677 | (interactive | |
3678 | (list (ad-read-regexp "Deactivate via advice regexp: "))) | |
3679 | (ad-do-advised-functions (function) | |
3680 | (if (ad-find-some-advice function 'any regexp) | |
3681 | (ad-deactivate function)))) | |
3682 | ||
3683 | (defun ad-update-regexp (regexp &optional compile) | |
3684 | "Updates functions with an advice name containing a REGEXP match. | |
fabaa9b5 | 3685 | See `ad-activate-on' for documentation on the optional COMPILE argument." |
ee7bf2ad RM |
3686 | (interactive |
3687 | (list (ad-read-regexp "Update via advice regexp: ") | |
3688 | current-prefix-arg)) | |
3689 | (ad-do-advised-functions (function) | |
3690 | (if (ad-find-some-advice function 'any regexp) | |
3691 | (ad-update function compile)))) | |
3692 | ||
3693 | (defun ad-activate-all (&optional compile) | |
3694 | "Activates all currently advised functions. | |
fabaa9b5 | 3695 | See `ad-activate-on' for documentation on the optional COMPILE argument." |
ee7bf2ad RM |
3696 | (interactive "P") |
3697 | (ad-do-advised-functions (function) | |
fabaa9b5 | 3698 | (ad-activate-on function compile))) |
ee7bf2ad RM |
3699 | |
3700 | (defun ad-deactivate-all () | |
3701 | "Deactivates all currently advised functions." | |
3702 | (interactive) | |
3703 | (ad-do-advised-functions (function) | |
3704 | (ad-deactivate function))) | |
3705 | ||
3706 | (defun ad-update-all (&optional compile) | |
3707 | "Updates all currently advised functions. | |
3708 | With prefix argument compiles resulting advised definitions." | |
3709 | (interactive "P") | |
3710 | (ad-do-advised-functions (function) | |
3711 | (ad-update function compile))) | |
3712 | ||
3713 | (defun ad-unadvise-all () | |
3714 | "Unadvises all currently advised functions." | |
3715 | (interactive) | |
3716 | (ad-do-advised-functions (function) | |
3717 | (ad-unadvise function))) | |
3718 | ||
3719 | (defun ad-recover-all () | |
6e2f6f45 | 3720 | "Recovers all currently advised functions. Use in emergencies." |
ee7bf2ad RM |
3721 | (interactive) |
3722 | (ad-do-advised-functions (function) | |
6e2f6f45 | 3723 | (condition-case nil |
ee7bf2ad RM |
3724 | (ad-recover function) |
3725 | (error nil)))) | |
3726 | ||
3727 | ||
3728 | ;; Completion alist of legal `defadvice' flags | |
3729 | (defvar ad-defadvice-flags | |
6e2f6f45 RS |
3730 | '(("protect") ("disable") ("activate") |
3731 | ("compile") ("preactivate") ("freeze"))) | |
ee7bf2ad RM |
3732 | |
3733 | ;;;###autoload | |
3734 | (defmacro defadvice (function args &rest body) | |
3735 | "Defines a piece of advice for FUNCTION (a symbol). | |
6e2f6f45 RS |
3736 | The syntax of `defadvice' is as follows: |
3737 | ||
3738 | (defadvice FUNCTION (CLASS NAME [POSITION] [ARGLIST] FLAG...) | |
3739 | [DOCSTRING] [INTERACTIVE-FORM] | |
3740 | BODY... ) | |
3741 | ||
3742 | FUNCTION ::= Name of the function to be advised. | |
3743 | CLASS ::= `before' | `around' | `after' | `activation' | `deactivation'. | |
3744 | NAME ::= Non-nil symbol that names this piece of advice. | |
3745 | POSITION ::= `first' | `last' | NUMBER. Optional, defaults to `first', | |
3746 | see also `ad-add-advice'. | |
3747 | ARGLIST ::= An optional argument list to be used for the advised function | |
3748 | instead of the argument list of the original. The first one found in | |
3749 | before/around/after-advices will be used. | |
3750 | FLAG ::= `protect'|`disable'|`activate'|`compile'|`preactivate'|`freeze'. | |
ee7bf2ad | 3751 | All flags can be specified with unambiguous initial substrings. |
6e2f6f45 RS |
3752 | DOCSTRING ::= Optional documentation for this piece of advice. |
3753 | INTERACTIVE-FORM ::= Optional interactive form to be used for the advised | |
3754 | function. The first one found in before/around/after-advices will be used. | |
3755 | BODY ::= Any s-expression. | |
ee7bf2ad RM |
3756 | |
3757 | Semantics of the various flags: | |
3758 | `protect': The piece of advice will be protected against non-local exits in | |
6e2f6f45 RS |
3759 | any code that precedes it. If any around-advice of a function is protected |
3760 | then automatically all around-advices will be protected (the complete onion). | |
ee7bf2ad RM |
3761 | |
3762 | `activate': All advice of FUNCTION will be activated immediately if | |
6e2f6f45 | 3763 | FUNCTION has been properly defined prior to this application of `defadvice'. |
ee7bf2ad RM |
3764 | |
3765 | `compile': In conjunction with `activate' specifies that the resulting | |
3766 | advised function should be compiled. | |
3767 | ||
6e2f6f45 | 3768 | `disable': The defined advice will be disabled, hence, it will not be used |
ee7bf2ad RM |
3769 | during activation until somebody enables it. |
3770 | ||
6e2f6f45 RS |
3771 | `preactivate': Preactivates the advised FUNCTION at macro-expansion/compile |
3772 | time. This generates a compiled advised definition according to the current | |
3773 | advice state that will be used during activation if appropriate. Only use | |
3774 | this if the `defadvice' gets actually compiled. | |
ee7bf2ad | 3775 | |
6e2f6f45 | 3776 | `freeze': Expands the `defadvice' into a redefining `defun/defmacro' according |
fabaa9b5 | 3777 | to this particular single advice. No other advice information will be saved. |
6e2f6f45 RS |
3778 | Frozen advices cannot be undone, they behave like a hard redefinition of |
3779 | the advised function. `freeze' implies `activate' and `preactivate'. The | |
3780 | documentation of the advised function can be dumped onto the `DOC' file | |
3781 | during preloading. | |
3782 | ||
3783 | Look at the file `advice.el' for comprehensive documentation." | |
ee7bf2ad RM |
3784 | (if (not (ad-name-p function)) |
3785 | (error "defadvice: Illegal function name: %s" function)) | |
3786 | (let* ((class (car args)) | |
3787 | (name (if (not (ad-class-p class)) | |
3788 | (error "defadvice: Illegal advice class: %s" class) | |
3789 | (nth 1 args))) | |
3790 | (position (if (not (ad-name-p name)) | |
3791 | (error "defadvice: Illegal advice name: %s" name) | |
3792 | (setq args (nthcdr 2 args)) | |
3793 | (if (ad-position-p (car args)) | |
3794 | (prog1 (car args) | |
3795 | (setq args (cdr args)))))) | |
3796 | (arglist (if (listp (car args)) | |
3797 | (prog1 (car args) | |
3798 | (setq args (cdr args))))) | |
3799 | (flags | |
3800 | (mapcar | |
3801 | (function | |
3802 | (lambda (flag) | |
3803 | (let ((completion | |
3804 | (try-completion (symbol-name flag) ad-defadvice-flags))) | |
3805 | (cond ((eq completion t) flag) | |
3806 | ((assoc completion ad-defadvice-flags) | |
3807 | (intern completion)) | |
3808 | (t (error "defadvice: Illegal or ambiguous flag: %s" | |
3809 | flag)))))) | |
3810 | args)) | |
3811 | (advice (ad-make-advice | |
3812 | name (memq 'protect flags) | |
3813 | (not (memq 'disable flags)) | |
3814 | (` (advice lambda (, arglist) (,@ body))))) | |
3815 | (preactivation (if (memq 'preactivate flags) | |
3816 | (ad-preactivate-advice | |
fabaa9b5 | 3817 | function advice class position)))) |
ee7bf2ad | 3818 | ;; Now for the things to be done at evaluation time: |
fabaa9b5 | 3819 | (if (memq 'freeze flags) |
6e2f6f45 RS |
3820 | ;; jwz's idea: Freeze the advised definition into a dumpable |
3821 | ;; defun/defmacro whose docs can be written to the DOC file: | |
fabaa9b5 | 3822 | (ad-make-freeze-definition function advice class position) |
6e2f6f45 RS |
3823 | ;; the normal case: |
3824 | (` (progn | |
3825 | (ad-add-advice '(, function) '(, advice) '(, class) '(, position)) | |
3826 | (,@ (if preactivation | |
3827 | (` ((ad-set-cache | |
3828 | '(, function) | |
3829 | ;; the function will get compiled: | |
3830 | (, (cond ((ad-macro-p (car preactivation)) | |
3831 | (` (ad-macrofy | |
3832 | (function | |
3833 | (, (ad-lambdafy | |
3834 | (car preactivation))))))) | |
3835 | (t (` (function | |
3836 | (, (car preactivation))))))) | |
3837 | '(, (car (cdr preactivation)))))))) | |
3838 | (,@ (if (memq 'activate flags) | |
fabaa9b5 RS |
3839 | (` ((ad-activate-on '(, function) |
3840 | (, (if (memq 'compile flags) t))))))) | |
6e2f6f45 | 3841 | '(, function)))))) |
ee7bf2ad RM |
3842 | |
3843 | ||
3844 | ;; @@ Tools: | |
3845 | ;; ========= | |
3846 | ||
3847 | (defmacro ad-with-originals (functions &rest body) | |
3848 | "Binds FUNCTIONS to their original definitions and executes BODY. | |
3849 | For any members of FUNCTIONS that are not currently advised the rebinding will | |
6e2f6f45 | 3850 | be a noop. Any modifications done to the definitions of FUNCTIONS will be |
ee7bf2ad RM |
3851 | undone on exit of this macro." |
3852 | (let* ((index -1) | |
3853 | ;; Make let-variables to store current definitions: | |
3854 | (current-bindings | |
3855 | (mapcar (function | |
3856 | (lambda (function) | |
3857 | (setq index (1+ index)) | |
3858 | (list (intern (format "ad-oRiGdEf-%d" index)) | |
3859 | (` (symbol-function '(, function)))))) | |
3860 | functions))) | |
3861 | (` (let (, current-bindings) | |
3862 | (unwind-protect | |
3863 | (progn | |
3864 | (,@ (progn | |
3865 | ;; Make forms to redefine functions to their | |
3866 | ;; original definitions if they are advised: | |
3867 | (setq index -1) | |
3868 | (mapcar | |
3869 | (function | |
3870 | (lambda (function) | |
3871 | (setq index (1+ index)) | |
fabaa9b5 | 3872 | (` (ad-safe-fset |
ee7bf2ad RM |
3873 | '(, function) |
3874 | (or (ad-get-orig-definition '(, function)) | |
3875 | (, (car (nth index current-bindings)))))))) | |
3876 | functions))) | |
3877 | (,@ body)) | |
3878 | (,@ (progn | |
3879 | ;; Make forms to back-define functions to the definitions | |
3880 | ;; they had outside this macro call: | |
3881 | (setq index -1) | |
3882 | (mapcar | |
3883 | (function | |
3884 | (lambda (function) | |
3885 | (setq index (1+ index)) | |
fabaa9b5 | 3886 | (` (ad-safe-fset |
ee7bf2ad RM |
3887 | '(, function) |
3888 | (, (car (nth index current-bindings))))))) | |
3889 | functions)))))))) | |
3890 | ||
3891 | (if (not (get 'ad-with-originals 'lisp-indent-hook)) | |
3892 | (put 'ad-with-originals 'lisp-indent-hook 1)) | |
3893 | ||
3894 | ||
fabaa9b5 RS |
3895 | ;; @@ Advising `documentation': |
3896 | ;; ============================ | |
3897 | ;; Use the advice mechanism to advise `documentation' to make it | |
3898 | ;; generate proper documentation strings for advised definitions: | |
ee7bf2ad RM |
3899 | |
3900 | (defadvice documentation (after ad-advised-docstring first disable preact) | |
3901 | "Builds an advised docstring if FUNCTION is advised." | |
3902 | ;; Because we get the function name from the advised docstring | |
3903 | ;; this will work for function names as well as for definitions: | |
3904 | (if (and (stringp ad-return-value) | |
3905 | (string-match | |
3906 | ad-advised-definition-docstring-regexp ad-return-value)) | |
3907 | (let ((function | |
3908 | (car (read-from-string | |
3909 | ad-return-value (match-beginning 1) (match-end 1))))) | |
3910 | (cond ((ad-is-advised function) | |
3911 | (setq ad-return-value (ad-make-advised-docstring function)) | |
6e2f6f45 | 3912 | ;; Handle optional `raw' argument: |
ee7bf2ad RM |
3913 | (if (not (ad-get-arg 1)) |
3914 | (setq ad-return-value | |
3915 | (substitute-command-keys ad-return-value)))))))) | |
835cd48e | 3916 | |
ee7bf2ad RM |
3917 | |
3918 | ;; @@ Starting, stopping and recovering from the advice package magic: | |
3919 | ;; =================================================================== | |
3920 | ||
ee7bf2ad | 3921 | (defun ad-start-advice () |
fabaa9b5 | 3922 | "Starts the automatic advice handling magic." |
ee7bf2ad | 3923 | (interactive) |
fabaa9b5 RS |
3924 | ;; Advising `ad-activate' means death!! |
3925 | (ad-set-advice-info 'ad-activate nil) | |
3926 | (ad-safe-fset 'ad-activate 'ad-activate-on) | |
ee7bf2ad | 3927 | (ad-enable-advice 'documentation 'after 'ad-advised-docstring) |
fabaa9b5 | 3928 | (ad-activate-on 'documentation 'compile)) |
ee7bf2ad RM |
3929 | |
3930 | (defun ad-stop-advice () | |
fabaa9b5 RS |
3931 | "Stops the automatic advice handling magic. |
3932 | You should only need this in case of Advice-related emergencies." | |
ee7bf2ad | 3933 | (interactive) |
fabaa9b5 RS |
3934 | ;; Advising `ad-activate' means death!! |
3935 | (ad-set-advice-info 'ad-activate nil) | |
ee7bf2ad RM |
3936 | (ad-disable-advice 'documentation 'after 'ad-advised-docstring) |
3937 | (ad-update 'documentation) | |
fabaa9b5 | 3938 | (ad-safe-fset 'ad-activate 'ad-activate-off)) |
ee7bf2ad | 3939 | |
ee7bf2ad RM |
3940 | (defun ad-recover-normality () |
3941 | "Undoes all advice related redefinitions and unadvises everything. | |
3942 | Use only in REAL emergencies." | |
3943 | (interactive) | |
fabaa9b5 RS |
3944 | ;; Advising `ad-activate' means death!! |
3945 | (ad-set-advice-info 'ad-activate nil) | |
3946 | (ad-safe-fset 'ad-activate 'ad-activate-off) | |
ee7bf2ad RM |
3947 | (ad-recover-all) |
3948 | (setq ad-advised-functions nil)) | |
3949 | ||
fabaa9b5 RS |
3950 | ;; Until the Advice-related changes to `data.c' are part of Lemacs we |
3951 | ;; have to load the old implementation of advice activation hooks: | |
3952 | (if (ad-lemacs-p) | |
3953 | (require 'ad-hooks)) | |
3954 | ||
3955 | (ad-start-advice) | |
ee7bf2ad RM |
3956 | |
3957 | (provide 'advice) | |
3958 | ||
3959 | ;;; advice.el ends here |