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73804d4b | 1 | @comment -*-texinfo-*- |
969fe9b5 | 2 | @c This is part of the GNU Emacs Lisp Reference Manual. |
f1224267 | 3 | @c Copyright (C) 1992-1994, 1998-1999, 2001-2012 Free Software Foundation, Inc. |
969fe9b5 | 4 | @c See the file elisp.texi for copying conditions. |
73804d4b | 5 | |
177c0ea7 JB |
6 | @c This file can also be used by an independent Edebug User |
7 | @c Manual in which case the Edebug node below should be used | |
73804d4b RS |
8 | @c with the following links to the Bugs section and to the top level: |
9 | ||
10 | @c , Bugs and Todo List, Top, Top | |
11 | ||
ecc6530d | 12 | @node Edebug |
73804d4b | 13 | @section Edebug |
77bf576c | 14 | @cindex Edebug debugging facility |
73804d4b | 15 | |
622fa380 | 16 | Edebug is a source-level debugger for Emacs Lisp programs, with which |
73804d4b RS |
17 | you can: |
18 | ||
19 | @itemize @bullet | |
20 | @item | |
21 | Step through evaluation, stopping before and after each expression. | |
22 | ||
23 | @item | |
24 | Set conditional or unconditional breakpoints. | |
25 | ||
26 | @item | |
27 | Stop when a specified condition is true (the global break event). | |
28 | ||
29 | @item | |
30 | Trace slow or fast, stopping briefly at each stop point, or | |
31 | at each breakpoint. | |
32 | ||
33 | @item | |
34 | Display expression results and evaluate expressions as if outside of | |
35 | Edebug. | |
36 | ||
177c0ea7 | 37 | @item |
a9f0a989 | 38 | Automatically re-evaluate a list of expressions and |
73804d4b RS |
39 | display their results each time Edebug updates the display. |
40 | ||
41 | @item | |
622fa380 | 42 | Output trace information on function calls and returns. |
73804d4b RS |
43 | |
44 | @item | |
45 | Stop when an error occurs. | |
46 | ||
47 | @item | |
48 | Display a backtrace, omitting Edebug's own frames. | |
49 | ||
50 | @item | |
51 | Specify argument evaluation for macros and defining forms. | |
52 | ||
53 | @item | |
54 | Obtain rudimentary coverage testing and frequency counts. | |
55 | @end itemize | |
56 | ||
57 | The first three sections below should tell you enough about Edebug to | |
622fa380 | 58 | start using it. |
73804d4b RS |
59 | |
60 | @menu | |
d24880de GM |
61 | * Using Edebug:: Introduction to use of Edebug. |
62 | * Instrumenting:: You must instrument your code | |
63 | in order to debug it with Edebug. | |
73804d4b | 64 | * Modes: Edebug Execution Modes. Execution modes, stopping more or less often. |
d24880de GM |
65 | * Jumping:: Commands to jump to a specified place. |
66 | * Misc: Edebug Misc. Miscellaneous commands. | |
c5f8bf2d | 67 | * Breaks:: Setting breakpoints to make the program stop. |
d24880de GM |
68 | * Trapping Errors:: Trapping errors with Edebug. |
69 | * Views: Edebug Views. Views inside and outside of Edebug. | |
70 | * Eval: Edebug Eval. Evaluating expressions within Edebug. | |
71 | * Eval List:: Expressions whose values are displayed | |
72 | each time you enter Edebug. | |
73 | * Printing in Edebug:: Customization of printing. | |
74 | * Trace Buffer:: How to produce trace output in a buffer. | |
75 | * Coverage Testing:: How to test evaluation coverage. | |
76 | * The Outside Context:: Data that Edebug saves and restores. | |
77 | * Edebug and Macros:: Specifying how to handle macro calls. | |
78 | * Options: Edebug Options. Option variables for customizing Edebug. | |
73804d4b RS |
79 | @end menu |
80 | ||
81 | @node Using Edebug | |
82 | @subsection Using Edebug | |
83 | ||
84 | To debug a Lisp program with Edebug, you must first @dfn{instrument} | |
85 | the Lisp code that you want to debug. A simple way to do this is to | |
86 | first move point into the definition of a function or macro and then do | |
87 | @kbd{C-u C-M-x} (@code{eval-defun} with a prefix argument). See | |
88 | @ref{Instrumenting}, for alternative ways to instrument code. | |
89 | ||
90 | Once a function is instrumented, any call to the function activates | |
8241495d RS |
91 | Edebug. Depending on which Edebug execution mode you have selected, |
92 | activating Edebug may stop execution and let you step through the | |
93 | function, or it may update the display and continue execution while | |
94 | checking for debugging commands. The default execution mode is step, | |
95 | which stops execution. @xref{Edebug Execution Modes}. | |
73804d4b RS |
96 | |
97 | Within Edebug, you normally view an Emacs buffer showing the source of | |
98 | the Lisp code you are debugging. This is referred to as the @dfn{source | |
2bdedac1 | 99 | code buffer}, and it is temporarily read-only. |
73804d4b | 100 | |
2634c6e4 | 101 | An arrow in the left fringe indicates the line where the function is |
73804d4b RS |
102 | executing. Point initially shows where within the line the function is |
103 | executing, but this ceases to be true if you move point yourself. | |
104 | ||
105 | If you instrument the definition of @code{fac} (shown below) and then | |
8241495d RS |
106 | execute @code{(fac 3)}, here is what you would normally see. Point is |
107 | at the open-parenthesis before @code{if}. | |
73804d4b RS |
108 | |
109 | @example | |
110 | (defun fac (n) | |
111 | =>@point{}(if (< 0 n) | |
112 | (* n (fac (1- n))) | |
113 | 1)) | |
114 | @end example | |
115 | ||
116 | @cindex stop points | |
117 | The places within a function where Edebug can stop execution are called | |
118 | @dfn{stop points}. These occur both before and after each subexpression | |
177c0ea7 | 119 | that is a list, and also after each variable reference. |
8241495d | 120 | Here we use periods to show the stop points in the function |
73804d4b RS |
121 | @code{fac}: |
122 | ||
123 | @example | |
124 | (defun fac (n) | |
125 | .(if .(< 0 n.). | |
b180eac2 | 126 | .(* n. .(fac .(1- n.).).). |
73804d4b RS |
127 | 1).) |
128 | @end example | |
129 | ||
130 | The special commands of Edebug are available in the source code buffer | |
131 | in addition to the commands of Emacs Lisp mode. For example, you can | |
132 | type the Edebug command @key{SPC} to execute until the next stop point. | |
133 | If you type @key{SPC} once after entry to @code{fac}, here is the | |
134 | display you will see: | |
135 | ||
136 | @example | |
137 | (defun fac (n) | |
138 | =>(if @point{}(< 0 n) | |
139 | (* n (fac (1- n))) | |
140 | 1)) | |
141 | @end example | |
142 | ||
143 | When Edebug stops execution after an expression, it displays the | |
177c0ea7 | 144 | expression's value in the echo area. |
73804d4b RS |
145 | |
146 | Other frequently used commands are @kbd{b} to set a breakpoint at a stop | |
147 | point, @kbd{g} to execute until a breakpoint is reached, and @kbd{q} to | |
148 | exit Edebug and return to the top-level command loop. Type @kbd{?} to | |
149 | display a list of all Edebug commands. | |
150 | ||
151 | @node Instrumenting | |
152 | @subsection Instrumenting for Edebug | |
287d7455 | 153 | @cindex instrumenting for Edebug |
73804d4b RS |
154 | |
155 | In order to use Edebug to debug Lisp code, you must first | |
156 | @dfn{instrument} the code. Instrumenting code inserts additional code | |
87b2d5ff | 157 | into it, to invoke Edebug at the proper places. |
73804d4b RS |
158 | |
159 | @kindex C-M-x | |
160 | @findex eval-defun (Edebug) | |
2634c6e4 RS |
161 | When you invoke command @kbd{C-M-x} (@code{eval-defun}) with a |
162 | prefix argument on a function definition, it instruments the | |
163 | definition before evaluating it. (This does not modify the source | |
164 | code itself.) If the variable @code{edebug-all-defs} is | |
165 | non-@code{nil}, that inverts the meaning of the prefix argument: in | |
166 | this case, @kbd{C-M-x} instruments the definition @emph{unless} it has | |
167 | a prefix argument. The default value of @code{edebug-all-defs} is | |
168 | @code{nil}. The command @kbd{M-x edebug-all-defs} toggles the value | |
169 | of the variable @code{edebug-all-defs}. | |
73804d4b | 170 | |
969fe9b5 | 171 | @findex eval-region @r{(Edebug)} |
d8ca18c7 | 172 | @findex eval-buffer @r{(Edebug)} |
969fe9b5 | 173 | @findex eval-current-buffer @r{(Edebug)} |
73804d4b RS |
174 | If @code{edebug-all-defs} is non-@code{nil}, then the commands |
175 | @code{eval-region}, @code{eval-current-buffer}, and @code{eval-buffer} | |
176 | also instrument any definitions they evaluate. Similarly, | |
177 | @code{edebug-all-forms} controls whether @code{eval-region} should | |
178 | instrument @emph{any} form, even non-defining forms. This doesn't apply | |
179 | to loading or evaluations in the minibuffer. The command @kbd{M-x | |
180 | edebug-all-forms} toggles this option. | |
181 | ||
182 | @findex edebug-eval-top-level-form | |
287d7455 | 183 | @findex edebug-defun |
969fe9b5 | 184 | Another command, @kbd{M-x edebug-eval-top-level-form}, is available to |
f9f59935 RS |
185 | instrument any top-level form regardless of the values of |
186 | @code{edebug-all-defs} and @code{edebug-all-forms}. | |
287d7455 | 187 | @code{edebug-defun} is an alias for @code{edebug-eval-top-level-form}. |
73804d4b | 188 | |
969fe9b5 | 189 | While Edebug is active, the command @kbd{I} |
73804d4b | 190 | (@code{edebug-instrument-callee}) instruments the definition of the |
da0bbbc4 | 191 | function or macro called by the list form after point, if it is not already |
73804d4b | 192 | instrumented. This is possible only if Edebug knows where to find the |
622fa380 | 193 | source for that function; for this reason, after loading Edebug, |
8241495d RS |
194 | @code{eval-region} records the position of every definition it |
195 | evaluates, even if not instrumenting it. See also the @kbd{i} command | |
196 | (@pxref{Jumping}), which steps into the call after instrumenting the | |
197 | function. | |
73804d4b | 198 | |
a9f0a989 RS |
199 | Edebug knows how to instrument all the standard special forms, |
200 | @code{interactive} forms with an expression argument, anonymous lambda | |
8241495d RS |
201 | expressions, and other defining forms. However, Edebug cannot determine |
202 | on its own what a user-defined macro will do with the arguments of a | |
67c1390d | 203 | macro call, so you must provide that information using Edebug |
622fa380 | 204 | specifications; for details, @pxref{Edebug and Macros}. |
73804d4b | 205 | |
969fe9b5 RS |
206 | When Edebug is about to instrument code for the first time in a |
207 | session, it runs the hook @code{edebug-setup-hook}, then sets it to | |
8241495d | 208 | @code{nil}. You can use this to load Edebug specifications |
67c1390d | 209 | associated with a package you are using, but only when you use Edebug. |
969fe9b5 RS |
210 | |
211 | @findex eval-expression @r{(Edebug)} | |
a9f0a989 | 212 | To remove instrumentation from a definition, simply re-evaluate its |
73804d4b | 213 | definition in a way that does not instrument. There are two ways of |
87b2d5ff | 214 | evaluating forms that never instrument them: from a file with |
73804d4b | 215 | @code{load}, and from the minibuffer with @code{eval-expression} |
bfe721d1 | 216 | (@kbd{M-:}). |
73804d4b RS |
217 | |
218 | If Edebug detects a syntax error while instrumenting, it leaves point | |
219 | at the erroneous code and signals an @code{invalid-read-syntax} error. | |
f1224267 | 220 | @c FIXME? I can't see that it "leaves point at the erroneous code". |
73804d4b RS |
221 | |
222 | @xref{Edebug Eval}, for other evaluation functions available | |
223 | inside of Edebug. | |
224 | ||
225 | @node Edebug Execution Modes | |
226 | @subsection Edebug Execution Modes | |
227 | ||
228 | @cindex Edebug execution modes | |
229 | Edebug supports several execution modes for running the program you are | |
230 | debugging. We call these alternatives @dfn{Edebug execution modes}; do | |
87b2d5ff | 231 | not confuse them with major or minor modes. The current Edebug execution mode |
73804d4b RS |
232 | determines how far Edebug continues execution before stopping---whether |
233 | it stops at each stop point, or continues to the next breakpoint, for | |
234 | example---and how much Edebug displays the progress of the evaluation | |
235 | before it stops. | |
236 | ||
237 | Normally, you specify the Edebug execution mode by typing a command to | |
238 | continue the program in a certain mode. Here is a table of these | |
8241495d | 239 | commands; all except for @kbd{S} resume execution of the program, at |
73804d4b RS |
240 | least for a certain distance. |
241 | ||
242 | @table @kbd | |
243 | @item S | |
8241495d | 244 | Stop: don't execute any more of the program, but wait for more |
73804d4b | 245 | Edebug commands (@code{edebug-stop}). |
f1224267 | 246 | @c FIXME Does not work. http://debbugs.gnu.org/9764 |
73804d4b RS |
247 | |
248 | @item @key{SPC} | |
249 | Step: stop at the next stop point encountered (@code{edebug-step-mode}). | |
250 | ||
251 | @item n | |
252 | Next: stop at the next stop point encountered after an expression | |
253 | (@code{edebug-next-mode}). Also see @code{edebug-forward-sexp} in | |
c5f8bf2d | 254 | @ref{Jumping}. |
73804d4b RS |
255 | |
256 | @item t | |
89f6de49 RS |
257 | Trace: pause (normally one second) at each Edebug stop point |
258 | (@code{edebug-trace-mode}). | |
73804d4b RS |
259 | |
260 | @item T | |
261 | Rapid trace: update the display at each stop point, but don't actually | |
262 | pause (@code{edebug-Trace-fast-mode}). | |
263 | ||
264 | @item g | |
265 | Go: run until the next breakpoint (@code{edebug-go-mode}). @xref{Breakpoints}. | |
266 | ||
267 | @item c | |
268 | Continue: pause one second at each breakpoint, and then continue | |
269 | (@code{edebug-continue-mode}). | |
270 | ||
271 | @item C | |
272 | Rapid continue: move point to each breakpoint, but don't pause | |
273 | (@code{edebug-Continue-fast-mode}). | |
274 | ||
275 | @item G | |
276 | Go non-stop: ignore breakpoints (@code{edebug-Go-nonstop-mode}). You | |
277 | can still stop the program by typing @kbd{S}, or any editing command. | |
278 | @end table | |
279 | ||
280 | In general, the execution modes earlier in the above list run the | |
87b2d5ff | 281 | program more slowly or stop sooner than the modes later in the list. |
73804d4b RS |
282 | |
283 | While executing or tracing, you can interrupt the execution by typing | |
284 | any Edebug command. Edebug stops the program at the next stop point and | |
87b2d5ff RS |
285 | then executes the command you typed. For example, typing @kbd{t} during |
286 | execution switches to trace mode at the next stop point. You can use | |
287 | @kbd{S} to stop execution without doing anything else. | |
73804d4b RS |
288 | |
289 | If your function happens to read input, a character you type intending | |
290 | to interrupt execution may be read by the function instead. You can | |
291 | avoid such unintended results by paying attention to when your program | |
292 | wants input. | |
293 | ||
294 | @cindex keyboard macros (Edebug) | |
295 | Keyboard macros containing the commands in this section do not | |
296 | completely work: exiting from Edebug, to resume the program, loses track | |
297 | of the keyboard macro. This is not easy to fix. Also, defining or | |
298 | executing a keyboard macro outside of Edebug does not affect commands | |
8241495d | 299 | inside Edebug. This is usually an advantage. See also the |
622fa380 | 300 | @code{edebug-continue-kbd-macro} option in @ref{Edebug Options}. |
73804d4b | 301 | |
2634c6e4 | 302 | When you enter a new Edebug level, the initial execution mode comes |
622fa380 GM |
303 | from the value of the variable @code{edebug-initial-mode} |
304 | (@pxref{Edebug Options}). By default, this specifies step mode. Note | |
2634c6e4 RS |
305 | that you may reenter the same Edebug level several times if, for |
306 | example, an instrumented function is called several times from one | |
307 | command. | |
73804d4b | 308 | |
89f6de49 RS |
309 | @defopt edebug-sit-for-seconds |
310 | This option specifies how many seconds to wait between execution steps | |
622fa380 | 311 | in trace mode or continue mode. The default is 1 second. |
b52a26fb | 312 | @end defopt |
73804d4b RS |
313 | |
314 | @node Jumping | |
315 | @subsection Jumping | |
316 | ||
317 | The commands described in this section execute until they reach a | |
318 | specified location. All except @kbd{i} make a temporary breakpoint to | |
319 | establish the place to stop, then switch to go mode. Any other | |
320 | breakpoint reached before the intended stop point will also stop | |
321 | execution. @xref{Breakpoints}, for the details on breakpoints. | |
322 | ||
323 | These commands may fail to work as expected in case of nonlocal exit, | |
8241495d RS |
324 | as that can bypass the temporary breakpoint where you expected the |
325 | program to stop. | |
73804d4b RS |
326 | |
327 | @table @kbd | |
328 | @item h | |
329 | Proceed to the stop point near where point is (@code{edebug-goto-here}). | |
330 | ||
331 | @item f | |
342fd6cd | 332 | Run the program for one expression |
73804d4b RS |
333 | (@code{edebug-forward-sexp}). |
334 | ||
335 | @item o | |
622fa380 | 336 | Run the program until the end of the containing sexp (@code{edebug-step-out}). |
73804d4b RS |
337 | |
338 | @item i | |
f1224267 GM |
339 | Step into the function or macro called by the form after point |
340 | (@code{edebug-step-in}). | |
73804d4b RS |
341 | @end table |
342 | ||
c5f8bf2d LT |
343 | The @kbd{h} command proceeds to the stop point at or after the current |
344 | location of point, using a temporary breakpoint. | |
73804d4b RS |
345 | |
346 | The @kbd{f} command runs the program forward over one expression. More | |
347 | precisely, it sets a temporary breakpoint at the position that | |
622fa380 GM |
348 | @code{forward-sexp} would reach, then executes in go mode so that |
349 | the program will stop at breakpoints. | |
73804d4b RS |
350 | |
351 | With a prefix argument @var{n}, the temporary breakpoint is placed | |
352 | @var{n} sexps beyond point. If the containing list ends before @var{n} | |
353 | more elements, then the place to stop is after the containing | |
354 | expression. | |
355 | ||
622fa380 GM |
356 | You must check that the position @code{forward-sexp} finds is a place |
357 | that the program will really get to. In @code{cond}, for example, | |
358 | this may not be true. | |
73804d4b | 359 | |
8241495d RS |
360 | For flexibility, the @kbd{f} command does @code{forward-sexp} starting |
361 | at point, rather than at the stop point. If you want to execute one | |
622fa380 GM |
362 | expression @emph{from the current stop point}, first type @kbd{w} |
363 | (@code{edebug-where}) to move point there, and then type @kbd{f}. | |
73804d4b RS |
364 | |
365 | The @kbd{o} command continues ``out of'' an expression. It places a | |
366 | temporary breakpoint at the end of the sexp containing point. If the | |
87b2d5ff RS |
367 | containing sexp is a function definition itself, @kbd{o} continues until |
368 | just before the last sexp in the definition. If that is where you are | |
369 | now, it returns from the function and then stops. In other words, this | |
73804d4b RS |
370 | command does not exit the currently executing function unless you are |
371 | positioned after the last sexp. | |
372 | ||
373 | The @kbd{i} command steps into the function or macro called by the list | |
87b2d5ff RS |
374 | form after point, and stops at its first stop point. Note that the form |
375 | need not be the one about to be evaluated. But if the form is a | |
376 | function call about to be evaluated, remember to use this command before | |
377 | any of the arguments are evaluated, since otherwise it will be too late. | |
73804d4b RS |
378 | |
379 | The @kbd{i} command instruments the function or macro it's supposed to | |
380 | step into, if it isn't instrumented already. This is convenient, but keep | |
381 | in mind that the function or macro remains instrumented unless you explicitly | |
382 | arrange to deinstrument it. | |
383 | ||
384 | @node Edebug Misc | |
385 | @subsection Miscellaneous Edebug Commands | |
386 | ||
387 | Some miscellaneous Edebug commands are described here. | |
388 | ||
389 | @table @kbd | |
390 | @item ? | |
391 | Display the help message for Edebug (@code{edebug-help}). | |
392 | ||
393 | @item C-] | |
394 | Abort one level back to the previous command level | |
395 | (@code{abort-recursive-edit}). | |
396 | ||
397 | @item q | |
398 | Return to the top level editor command loop (@code{top-level}). This | |
399 | exits all recursive editing levels, including all levels of Edebug | |
400 | activity. However, instrumented code protected with | |
401 | @code{unwind-protect} or @code{condition-case} forms may resume | |
402 | debugging. | |
403 | ||
404 | @item Q | |
8241495d | 405 | Like @kbd{q}, but don't stop even for protected code |
622fa380 | 406 | (@code{edebug-top-level-nonstop}). |
73804d4b RS |
407 | |
408 | @item r | |
409 | Redisplay the most recently known expression result in the echo area | |
410 | (@code{edebug-previous-result}). | |
411 | ||
412 | @item d | |
413 | Display a backtrace, excluding Edebug's own functions for clarity | |
414 | (@code{edebug-backtrace}). | |
415 | ||
416 | You cannot use debugger commands in the backtrace buffer in Edebug as | |
417 | you would in the standard debugger. | |
418 | ||
419 | The backtrace buffer is killed automatically when you continue | |
420 | execution. | |
421 | @end table | |
422 | ||
8241495d RS |
423 | You can invoke commands from Edebug that activate Edebug again |
424 | recursively. Whenever Edebug is active, you can quit to the top level | |
425 | with @kbd{q} or abort one recursive edit level with @kbd{C-]}. You can | |
426 | display a backtrace of all the pending evaluations with @kbd{d}. | |
73804d4b | 427 | |
c5f8bf2d LT |
428 | @node Breaks |
429 | @subsection Breaks | |
73804d4b | 430 | |
8241495d | 431 | Edebug's step mode stops execution when the next stop point is reached. |
73804d4b RS |
432 | There are three other ways to stop Edebug execution once it has started: |
433 | breakpoints, the global break condition, and source breakpoints. | |
434 | ||
c5f8bf2d LT |
435 | @menu |
436 | * Breakpoints:: Breakpoints at stop points. | |
d24880de GM |
437 | * Global Break Condition:: Breaking on an event. |
438 | * Source Breakpoints:: Embedding breakpoints in source code. | |
c5f8bf2d LT |
439 | @end menu |
440 | ||
441 | @node Breakpoints | |
77bf576c | 442 | @subsubsection Edebug Breakpoints |
c5f8bf2d | 443 | |
77bf576c | 444 | @cindex breakpoints (Edebug) |
73804d4b | 445 | While using Edebug, you can specify @dfn{breakpoints} in the program you |
8241495d | 446 | are testing: these are places where execution should stop. You can set a |
73804d4b RS |
447 | breakpoint at any stop point, as defined in @ref{Using Edebug}. For |
448 | setting and unsetting breakpoints, the stop point that is affected is | |
449 | the first one at or after point in the source code buffer. Here are the | |
450 | Edebug commands for breakpoints: | |
451 | ||
452 | @table @kbd | |
453 | @item b | |
454 | Set a breakpoint at the stop point at or after point | |
455 | (@code{edebug-set-breakpoint}). If you use a prefix argument, the | |
8241495d RS |
456 | breakpoint is temporary---it turns off the first time it stops the |
457 | program. | |
73804d4b RS |
458 | |
459 | @item u | |
177c0ea7 | 460 | Unset the breakpoint (if any) at the stop point at or after |
73804d4b RS |
461 | point (@code{edebug-unset-breakpoint}). |
462 | ||
463 | @item x @var{condition} @key{RET} | |
464 | Set a conditional breakpoint which stops the program only if | |
342fd6cd RS |
465 | evaluating @var{condition} produces a non-@code{nil} value |
466 | (@code{edebug-set-conditional-breakpoint}). With a prefix argument, | |
467 | the breakpoint is temporary. | |
73804d4b RS |
468 | |
469 | @item B | |
9e2b495b | 470 | Move point to the next breakpoint in the current definition |
73804d4b RS |
471 | (@code{edebug-next-breakpoint}). |
472 | @end table | |
473 | ||
474 | While in Edebug, you can set a breakpoint with @kbd{b} and unset one | |
475 | with @kbd{u}. First move point to the Edebug stop point of your choice, | |
476 | then type @kbd{b} or @kbd{u} to set or unset a breakpoint there. | |
477 | Unsetting a breakpoint where none has been set has no effect. | |
478 | ||
8241495d RS |
479 | Re-evaluating or reinstrumenting a definition removes all of its |
480 | previous breakpoints. | |
73804d4b RS |
481 | |
482 | A @dfn{conditional breakpoint} tests a condition each time the program | |
483 | gets there. Any errors that occur as a result of evaluating the | |
484 | condition are ignored, as if the result were @code{nil}. To set a | |
485 | conditional breakpoint, use @kbd{x}, and specify the condition | |
486 | expression in the minibuffer. Setting a conditional breakpoint at a | |
487 | stop point that has a previously established conditional breakpoint puts | |
488 | the previous condition expression in the minibuffer so you can edit it. | |
489 | ||
490 | You can make a conditional or unconditional breakpoint | |
969fe9b5 | 491 | @dfn{temporary} by using a prefix argument with the command to set the |
73804d4b RS |
492 | breakpoint. When a temporary breakpoint stops the program, it is |
493 | automatically unset. | |
494 | ||
8241495d | 495 | Edebug always stops or pauses at a breakpoint, except when the Edebug |
73804d4b RS |
496 | mode is Go-nonstop. In that mode, it ignores breakpoints entirely. |
497 | ||
498 | To find out where your breakpoints are, use the @kbd{B} command, which | |
87b2d5ff RS |
499 | moves point to the next breakpoint following point, within the same |
500 | function, or to the first breakpoint if there are no following | |
501 | breakpoints. This command does not continue execution---it just moves | |
502 | point in the buffer. | |
73804d4b | 503 | |
73804d4b RS |
504 | @node Global Break Condition |
505 | @subsubsection Global Break Condition | |
506 | ||
507 | @cindex stopping on events | |
508 | @cindex global break condition | |
509 | A @dfn{global break condition} stops execution when a specified | |
510 | condition is satisfied, no matter where that may occur. Edebug | |
8241495d | 511 | evaluates the global break condition at every stop point; if it |
73804d4b RS |
512 | evaluates to a non-@code{nil} value, then execution stops or pauses |
513 | depending on the execution mode, as if a breakpoint had been hit. If | |
514 | evaluating the condition gets an error, execution does not stop. | |
515 | ||
516 | @findex edebug-set-global-break-condition | |
9e2b495b RS |
517 | The condition expression is stored in |
518 | @code{edebug-global-break-condition}. You can specify a new expression | |
c5f8bf2d LT |
519 | using the @kbd{X} command from the source code buffer while Edebug is |
520 | active, or using @kbd{C-x X X} from any buffer at any time, as long as | |
521 | Edebug is loaded (@code{edebug-set-global-break-condition}). | |
73804d4b RS |
522 | |
523 | The global break condition is the simplest way to find where in your | |
524 | code some event occurs, but it makes code run much more slowly. So you | |
525 | should reset the condition to @code{nil} when not using it. | |
526 | ||
527 | @node Source Breakpoints | |
528 | @subsubsection Source Breakpoints | |
529 | ||
530 | @findex edebug | |
531 | @cindex source breakpoints | |
532 | All breakpoints in a definition are forgotten each time you | |
8241495d RS |
533 | reinstrument it. If you wish to make a breakpoint that won't be |
534 | forgotten, you can write a @dfn{source breakpoint}, which is simply a | |
535 | call to the function @code{edebug} in your source code. You can, of | |
536 | course, make such a call conditional. For example, in the @code{fac} | |
537 | function, you can insert the first line as shown below, to stop when the | |
538 | argument reaches zero: | |
73804d4b RS |
539 | |
540 | @example | |
541 | (defun fac (n) | |
542 | (if (= n 0) (edebug)) | |
543 | (if (< 0 n) | |
544 | (* n (fac (1- n))) | |
545 | 1)) | |
546 | @end example | |
547 | ||
969fe9b5 | 548 | When the @code{fac} definition is instrumented and the function is |
73804d4b RS |
549 | called, the call to @code{edebug} acts as a breakpoint. Depending on |
550 | the execution mode, Edebug stops or pauses there. | |
551 | ||
969fe9b5 | 552 | If no instrumented code is being executed when @code{edebug} is called, |
73804d4b RS |
553 | that function calls @code{debug}. |
554 | @c This may not be a good idea anymore. | |
555 | ||
556 | @node Trapping Errors | |
557 | @subsection Trapping Errors | |
558 | ||
969fe9b5 RS |
559 | Emacs normally displays an error message when an error is signaled and |
560 | not handled with @code{condition-case}. While Edebug is active and | |
561 | executing instrumented code, it normally responds to all unhandled | |
562 | errors. You can customize this with the options @code{edebug-on-error} | |
563 | and @code{edebug-on-quit}; see @ref{Edebug Options}. | |
73804d4b | 564 | |
969fe9b5 | 565 | When Edebug responds to an error, it shows the last stop point |
73804d4b | 566 | encountered before the error. This may be the location of a call to a |
8241495d | 567 | function which was not instrumented, and within which the error actually |
73804d4b RS |
568 | occurred. For an unbound variable error, the last known stop point |
569 | might be quite distant from the offending variable reference. In that | |
8241495d | 570 | case, you might want to display a full backtrace (@pxref{Edebug Misc}). |
73804d4b | 571 | |
87b2d5ff | 572 | @c Edebug should be changed for the following: -- dan |
969fe9b5 | 573 | If you change @code{debug-on-error} or @code{debug-on-quit} while |
73804d4b RS |
574 | Edebug is active, these changes will be forgotten when Edebug becomes |
575 | inactive. Furthermore, during Edebug's recursive edit, these variables | |
576 | are bound to the values they had outside of Edebug. | |
577 | ||
73804d4b RS |
578 | @node Edebug Views |
579 | @subsection Edebug Views | |
580 | ||
969fe9b5 | 581 | These Edebug commands let you view aspects of the buffer and window |
a9f0a989 | 582 | status as they were before entry to Edebug. The outside window |
87b2d5ff RS |
583 | configuration is the collection of windows and contents that were in |
584 | effect outside of Edebug. | |
73804d4b RS |
585 | |
586 | @table @kbd | |
587 | @item v | |
342fd6cd RS |
588 | Switch to viewing the outside window configuration |
589 | (@code{edebug-view-outside}). Type @kbd{C-x X w} to return to Edebug. | |
73804d4b RS |
590 | |
591 | @item p | |
c5f8bf2d LT |
592 | Temporarily display the outside current buffer with point at its |
593 | outside position (@code{edebug-bounce-point}), pausing for one second | |
594 | before returning to Edebug. With a prefix argument @var{n}, pause for | |
595 | @var{n} seconds instead. | |
73804d4b RS |
596 | |
597 | @item w | |
1911e6e5 RS |
598 | Move point back to the current stop point in the source code buffer |
599 | (@code{edebug-where}). | |
600 | ||
601 | If you use this command in a different window displaying the same | |
602 | buffer, that window will be used instead to display the current | |
603 | definition in the future. | |
73804d4b RS |
604 | |
605 | @item W | |
87b2d5ff RS |
606 | @c Its function is not simply to forget the saved configuration -- dan |
607 | Toggle whether Edebug saves and restores the outside window | |
608 | configuration (@code{edebug-toggle-save-windows}). | |
609 | ||
610 | With a prefix argument, @code{W} only toggles saving and restoring of | |
611 | the selected window. To specify a window that is not displaying the | |
612 | source code buffer, you must use @kbd{C-x X W} from the global keymap. | |
73804d4b RS |
613 | @end table |
614 | ||
969fe9b5 | 615 | You can view the outside window configuration with @kbd{v} or just |
73804d4b | 616 | bounce to the point in the current buffer with @kbd{p}, even if |
c5f8bf2d LT |
617 | it is not normally displayed. |
618 | ||
619 | After moving point, you may wish to jump back to the stop point. | |
620 | You can do that with @kbd{w} from a source code buffer. You can jump | |
621 | back to the stop point in the source code buffer from any buffer using | |
622 | @kbd{C-x X w}. | |
73804d4b | 623 | |
969fe9b5 | 624 | Each time you use @kbd{W} to turn saving @emph{off}, Edebug forgets the |
87b2d5ff RS |
625 | saved outside window configuration---so that even if you turn saving |
626 | back @emph{on}, the current window configuration remains unchanged when | |
627 | you next exit Edebug (by continuing the program). However, the | |
2bb0eca1 | 628 | automatic redisplay of @file{*edebug*} and @file{*edebug-trace*} may |
87b2d5ff RS |
629 | conflict with the buffers you wish to see unless you have enough windows |
630 | open. | |
73804d4b RS |
631 | |
632 | @node Edebug Eval | |
633 | @subsection Evaluation | |
634 | ||
650b6d0b | 635 | While within Edebug, you can evaluate expressions as if Edebug |
8241495d | 636 | were not running. Edebug tries to be invisible to the expression's |
73804d4b | 637 | evaluation and printing. Evaluation of expressions that cause side |
8241495d RS |
638 | effects will work as expected, except for changes to data that Edebug |
639 | explicitly saves and restores. @xref{The Outside Context}, for details | |
640 | on this process. | |
73804d4b RS |
641 | |
642 | @table @kbd | |
643 | @item e @var{exp} @key{RET} | |
644 | Evaluate expression @var{exp} in the context outside of Edebug | |
645 | (@code{edebug-eval-expression}). That is, Edebug tries to minimize its | |
646 | interference with the evaluation. | |
647 | ||
bfe721d1 | 648 | @item M-: @var{exp} @key{RET} |
622fa380 GM |
649 | Evaluate expression @var{exp} in the context of Edebug itself |
650 | (@code{eval-expression}). | |
73804d4b RS |
651 | |
652 | @item C-x C-e | |
653 | Evaluate the expression before point, in the context outside of Edebug | |
654 | (@code{edebug-eval-last-sexp}). | |
655 | @end table | |
656 | ||
657 | @cindex lexical binding (Edebug) | |
969fe9b5 | 658 | Edebug supports evaluation of expressions containing references to |
73804d4b | 659 | lexically bound symbols created by the following constructs in |
622fa380 GM |
660 | @file{cl.el}: @code{lexical-let}, @code{macrolet}, and |
661 | @code{symbol-macrolet}. | |
650b6d0b | 662 | @c FIXME? What about lexical-binding = t? |
73804d4b | 663 | |
73804d4b RS |
664 | @node Eval List |
665 | @subsection Evaluation List Buffer | |
666 | ||
2bb0eca1 | 667 | You can use the @dfn{evaluation list buffer}, called @file{*edebug*}, to |
73804d4b RS |
668 | evaluate expressions interactively. You can also set up the |
669 | @dfn{evaluation list} of expressions to be evaluated automatically each | |
670 | time Edebug updates the display. | |
671 | ||
672 | @table @kbd | |
673 | @item E | |
2bb0eca1 | 674 | Switch to the evaluation list buffer @file{*edebug*} |
73804d4b RS |
675 | (@code{edebug-visit-eval-list}). |
676 | @end table | |
677 | ||
2bb0eca1 | 678 | In the @file{*edebug*} buffer you can use the commands of Lisp |
73804d4b RS |
679 | Interaction mode (@pxref{Lisp Interaction,,, emacs, The GNU Emacs |
680 | Manual}) as well as these special commands: | |
681 | ||
682 | @table @kbd | |
969fe9b5 | 683 | @item C-j |
73804d4b RS |
684 | Evaluate the expression before point, in the outside context, and insert |
685 | the value in the buffer (@code{edebug-eval-print-last-sexp}). | |
686 | ||
687 | @item C-x C-e | |
688 | Evaluate the expression before point, in the context outside of Edebug | |
689 | (@code{edebug-eval-last-sexp}). | |
690 | ||
691 | @item C-c C-u | |
87b2d5ff | 692 | Build a new evaluation list from the contents of the buffer |
73804d4b RS |
693 | (@code{edebug-update-eval-list}). |
694 | ||
695 | @item C-c C-d | |
696 | Delete the evaluation list group that point is in | |
697 | (@code{edebug-delete-eval-item}). | |
698 | ||
699 | @item C-c C-w | |
700 | Switch back to the source code buffer at the current stop point | |
701 | (@code{edebug-where}). | |
702 | @end table | |
703 | ||
969fe9b5 | 704 | You can evaluate expressions in the evaluation list window with |
2bb0eca1 | 705 | @kbd{C-j} or @kbd{C-x C-e}, just as you would in @file{*scratch*}; |
73804d4b RS |
706 | but they are evaluated in the context outside of Edebug. |
707 | ||
969fe9b5 | 708 | The expressions you enter interactively (and their results) are lost |
73804d4b | 709 | when you continue execution; but you can set up an @dfn{evaluation list} |
177c0ea7 | 710 | consisting of expressions to be evaluated each time execution stops. |
73804d4b RS |
711 | |
712 | @cindex evaluation list group | |
969fe9b5 | 713 | To do this, write one or more @dfn{evaluation list groups} in the |
73804d4b RS |
714 | evaluation list buffer. An evaluation list group consists of one or |
715 | more Lisp expressions. Groups are separated by comment lines. | |
716 | ||
969fe9b5 | 717 | The command @kbd{C-c C-u} (@code{edebug-update-eval-list}) rebuilds the |
73804d4b | 718 | evaluation list, scanning the buffer and using the first expression of |
87b2d5ff RS |
719 | each group. (The idea is that the second expression of the group is the |
720 | value previously computed and displayed.) | |
73804d4b | 721 | |
969fe9b5 | 722 | Each entry to Edebug redisplays the evaluation list by inserting each |
87b2d5ff RS |
723 | expression in the buffer, followed by its current value. It also |
724 | inserts comment lines so that each expression becomes its own group. | |
725 | Thus, if you type @kbd{C-c C-u} again without changing the buffer text, | |
726 | the evaluation list is effectively unchanged. | |
73804d4b | 727 | |
622fa380 GM |
728 | If an error occurs during an evaluation from the evaluation list, |
729 | the error message is displayed in a string as if it were the result. | |
730 | Therefore, expressions using variables that are not currently valid do | |
731 | not interrupt your debugging. | |
73804d4b | 732 | |
969fe9b5 | 733 | Here is an example of what the evaluation list window looks like after |
73804d4b RS |
734 | several expressions have been added to it: |
735 | ||
736 | @smallexample | |
737 | (current-buffer) | |
738 | #<buffer *scratch*> | |
739 | ;--------------------------------------------------------------- | |
740 | (selected-window) | |
741 | #<window 16 on *scratch*> | |
742 | ;--------------------------------------------------------------- | |
743 | (point) | |
744 | 196 | |
745 | ;--------------------------------------------------------------- | |
746 | bad-var | |
747 | "Symbol's value as variable is void: bad-var" | |
748 | ;--------------------------------------------------------------- | |
749 | (recursion-depth) | |
750 | 0 | |
751 | ;--------------------------------------------------------------- | |
752 | this-command | |
753 | eval-last-sexp | |
754 | ;--------------------------------------------------------------- | |
755 | @end smallexample | |
756 | ||
757 | To delete a group, move point into it and type @kbd{C-c C-d}, or simply | |
758 | delete the text for the group and update the evaluation list with | |
759 | @kbd{C-c C-u}. To add a new expression to the evaluation list, insert | |
8241495d RS |
760 | the expression at a suitable place, insert a new comment line, then type |
761 | @kbd{C-c C-u}. You need not insert dashes in the comment line---its | |
762 | contents don't matter. | |
73804d4b | 763 | |
2bb0eca1 GM |
764 | After selecting @file{*edebug*}, you can return to the source code |
765 | buffer with @kbd{C-c C-w}. The @file{*edebug*} buffer is killed when | |
73804d4b RS |
766 | you continue execution, and recreated next time it is needed. |
767 | ||
73804d4b RS |
768 | @node Printing in Edebug |
769 | @subsection Printing in Edebug | |
770 | ||
771 | @cindex printing (Edebug) | |
772 | @cindex printing circular structures | |
773 | @pindex cust-print | |
774 | If an expression in your program produces a value containing circular | |
775 | list structure, you may get an error when Edebug attempts to print it. | |
776 | ||
73804d4b RS |
777 | One way to cope with circular structure is to set @code{print-length} |
778 | or @code{print-level} to truncate the printing. Edebug does this for | |
622fa380 GM |
779 | you; it binds @code{print-length} and @code{print-level} to the values |
780 | of the variables @code{edebug-print-length} and | |
781 | @code{edebug-print-level} (so long as they have non-@code{nil} | |
782 | values). @xref{Output Variables}. | |
73804d4b | 783 | |
969fe9b5 | 784 | @defopt edebug-print-length |
8241495d RS |
785 | If non-@code{nil}, Edebug binds @code{print-length} to this value while |
786 | printing results. The default value is @code{50}. | |
969fe9b5 RS |
787 | @end defopt |
788 | ||
177c0ea7 | 789 | @defopt edebug-print-level |
8241495d RS |
790 | If non-@code{nil}, Edebug binds @code{print-level} to this value while |
791 | printing results. The default value is @code{50}. | |
969fe9b5 RS |
792 | @end defopt |
793 | ||
73804d4b | 794 | You can also print circular structures and structures that share |
8241495d RS |
795 | elements more informatively by binding @code{print-circle} |
796 | to a non-@code{nil} value. | |
73804d4b RS |
797 | |
798 | Here is an example of code that creates a circular structure: | |
799 | ||
800 | @example | |
801 | (setq a '(x y)) | |
a9f0a989 | 802 | (setcar a a) |
73804d4b RS |
803 | @end example |
804 | ||
805 | @noindent | |
806 | Custom printing prints this as @samp{Result: #1=(#1# y)}. The | |
807 | @samp{#1=} notation labels the structure that follows it with the label | |
a9f0a989 | 808 | @samp{1}, and the @samp{#1#} notation references the previously labeled |
73804d4b RS |
809 | structure. This notation is used for any shared elements of lists or |
810 | vectors. | |
811 | ||
177c0ea7 | 812 | @defopt edebug-print-circle |
8241495d | 813 | If non-@code{nil}, Edebug binds @code{print-circle} to this value while |
011caae1 | 814 | printing results. The default value is @code{t}. |
969fe9b5 RS |
815 | @end defopt |
816 | ||
73804d4b RS |
817 | Other programs can also use custom printing; see @file{cust-print.el} |
818 | for details. | |
819 | ||
820 | @node Trace Buffer | |
821 | @subsection Trace Buffer | |
822 | @cindex trace buffer | |
823 | ||
87b2d5ff | 824 | Edebug can record an execution trace, storing it in a buffer named |
2bb0eca1 | 825 | @file{*edebug-trace*}. This is a log of function calls and returns, |
73804d4b RS |
826 | showing the function names and their arguments and values. To enable |
827 | trace recording, set @code{edebug-trace} to a non-@code{nil} value. | |
828 | ||
829 | Making a trace buffer is not the same thing as using trace execution | |
830 | mode (@pxref{Edebug Execution Modes}). | |
831 | ||
832 | When trace recording is enabled, each function entry and exit adds | |
8241495d RS |
833 | lines to the trace buffer. A function entry record consists of |
834 | @samp{::::@{}, followed by the function name and argument values. A | |
835 | function exit record consists of @samp{::::@}}, followed by the function | |
73804d4b RS |
836 | name and result of the function. |
837 | ||
838 | The number of @samp{:}s in an entry shows its recursion depth. You | |
839 | can use the braces in the trace buffer to find the matching beginning or | |
840 | end of function calls. | |
841 | ||
842 | @findex edebug-print-trace-before | |
843 | @findex edebug-print-trace-after | |
844 | You can customize trace recording for function entry and exit by | |
845 | redefining the functions @code{edebug-print-trace-before} and | |
846 | @code{edebug-print-trace-after}. | |
847 | ||
848 | @defmac edebug-tracing string body@dots{} | |
849 | This macro requests additional trace information around the execution | |
850 | of the @var{body} forms. The argument @var{string} specifies text | |
c5f8bf2d LT |
851 | to put in the trace buffer, after the @samp{@{} or @samp{@}}. All |
852 | the arguments are evaluated, and @code{edebug-tracing} returns the | |
853 | value of the last form in @var{body}. | |
73804d4b RS |
854 | @end defmac |
855 | ||
856 | @defun edebug-trace format-string &rest format-args | |
857 | This function inserts text in the trace buffer. It computes the text | |
858 | with @code{(apply 'format @var{format-string} @var{format-args})}. | |
87b2d5ff | 859 | It also appends a newline to separate entries. |
73804d4b RS |
860 | @end defun |
861 | ||
1911e6e5 RS |
862 | @code{edebug-tracing} and @code{edebug-trace} insert lines in the |
863 | trace buffer whenever they are called, even if Edebug is not active. | |
864 | Adding text to the trace buffer also scrolls its window to show the last | |
865 | lines inserted. | |
73804d4b | 866 | |
73804d4b RS |
867 | @node Coverage Testing |
868 | @subsection Coverage Testing | |
869 | ||
77bf576c | 870 | @cindex coverage testing (Edebug) |
73804d4b RS |
871 | @cindex frequency counts |
872 | @cindex performance analysis | |
77bf576c | 873 | Edebug provides rudimentary coverage testing and display of execution |
1911e6e5 RS |
874 | frequency. |
875 | ||
876 | Coverage testing works by comparing the result of each expression with | |
877 | the previous result; each form in the program is considered ``covered'' | |
878 | if it has returned two different values since you began testing coverage | |
879 | in the current Emacs session. Thus, to do coverage testing on your | |
880 | program, execute it under various conditions and note whether it behaves | |
881 | correctly; Edebug will tell you when you have tried enough different | |
882 | conditions that each form has returned two different values. | |
883 | ||
884 | Coverage testing makes execution slower, so it is only done if | |
ebc6903b | 885 | @code{edebug-test-coverage} is non-@code{nil}. Frequency counting is |
622fa380 | 886 | performed for all executions of an instrumented function, even if the |
ebc6903b RS |
887 | execution mode is Go-nonstop, and regardless of whether coverage testing |
888 | is enabled. | |
1911e6e5 | 889 | |
89f6de49 RS |
890 | @kindex C-x X = |
891 | @findex edebug-temp-display-freq-count | |
892 | Use @kbd{C-x X =} (@code{edebug-display-freq-count}) to display both | |
893 | the coverage information and the frequency counts for a definition. | |
894 | Just @kbd{=} (@code{edebug-temp-display-freq-count}) displays the same | |
895 | information temporarily, only until you type another key. | |
73804d4b RS |
896 | |
897 | @deffn Command edebug-display-freq-count | |
898 | This command displays the frequency count data for each line of the | |
899 | current definition. | |
900 | ||
622fa380 GM |
901 | It inserts frequency counts as comment lines after each line of code. |
902 | You can undo all insertions with one @code{undo} command. The counts | |
903 | appear under the @samp{(} before an expression or the @samp{)} after | |
904 | an expression, or on the last character of a variable. To simplify | |
905 | the display, a count is not shown if it is equal to the count of an | |
906 | earlier expression on the same line. | |
73804d4b RS |
907 | |
908 | The character @samp{=} following the count for an expression says that | |
a9f0a989 | 909 | the expression has returned the same value each time it was evaluated. |
1911e6e5 | 910 | In other words, it is not yet ``covered'' for coverage testing purposes. |
73804d4b RS |
911 | |
912 | To clear the frequency count and coverage data for a definition, | |
a9f0a989 | 913 | simply reinstrument it with @code{eval-defun}. |
73804d4b RS |
914 | @end deffn |
915 | ||
916 | For example, after evaluating @code{(fac 5)} with a source | |
917 | breakpoint, and setting @code{edebug-test-coverage} to @code{t}, when | |
918 | the breakpoint is reached, the frequency data looks like this: | |
919 | ||
920 | @example | |
921 | (defun fac (n) | |
922 | (if (= n 0) (edebug)) | |
011caae1 | 923 | ;#6 1 = =5 |
73804d4b | 924 | (if (< 0 n) |
177c0ea7 | 925 | ;#5 = |
73804d4b | 926 | (* n (fac (1- n))) |
177c0ea7 | 927 | ;# 5 0 |
73804d4b | 928 | 1)) |
177c0ea7 | 929 | ;# 0 |
73804d4b RS |
930 | @end example |
931 | ||
87b2d5ff RS |
932 | The comment lines show that @code{fac} was called 6 times. The |
933 | first @code{if} statement returned 5 times with the same result each | |
73804d4b | 934 | time; the same is true of the condition on the second @code{if}. |
87b2d5ff | 935 | The recursive call of @code{fac} did not return at all. |
73804d4b RS |
936 | |
937 | ||
938 | @node The Outside Context | |
939 | @subsection The Outside Context | |
940 | ||
941 | Edebug tries to be transparent to the program you are debugging, but it | |
942 | does not succeed completely. Edebug also tries to be transparent when | |
943 | you evaluate expressions with @kbd{e} or with the evaluation list | |
944 | buffer, by temporarily restoring the outside context. This section | |
945 | explains precisely what context Edebug restores, and how Edebug fails to | |
946 | be completely transparent. | |
947 | ||
73804d4b | 948 | @menu |
d24880de GM |
949 | * Checking Whether to Stop:: When Edebug decides what to do. |
950 | * Edebug Display Update:: When Edebug updates the display. | |
951 | * Edebug Recursive Edit:: When Edebug stops execution. | |
73804d4b RS |
952 | @end menu |
953 | ||
954 | @node Checking Whether to Stop | |
955 | @subsubsection Checking Whether to Stop | |
956 | ||
87b2d5ff RS |
957 | Whenever Edebug is entered, it needs to save and restore certain data |
958 | before even deciding whether to make trace information or stop the | |
959 | program. | |
73804d4b RS |
960 | |
961 | @itemize @bullet | |
177c0ea7 | 962 | @item |
73804d4b | 963 | @code{max-lisp-eval-depth} and @code{max-specpdl-size} are both |
622fa380 GM |
964 | increased to reduce Edebug's impact on the stack. You could, however, |
965 | still run out of stack space when using Edebug. | |
73804d4b | 966 | |
177c0ea7 | 967 | @item |
73804d4b | 968 | The state of keyboard macro execution is saved and restored. While |
473671bd RS |
969 | Edebug is active, @code{executing-kbd-macro} is bound to @code{nil} |
970 | unless @code{edebug-continue-kbd-macro} is non-@code{nil}. | |
73804d4b RS |
971 | @end itemize |
972 | ||
973 | ||
974 | @node Edebug Display Update | |
975 | @subsubsection Edebug Display Update | |
976 | ||
87b2d5ff RS |
977 | @c This paragraph is not filled, because LaLiberte's conversion script |
978 | @c needs an xref to be on just one line. | |
73804d4b | 979 | When Edebug needs to display something (e.g., in trace mode), it saves |
177c0ea7 | 980 | the current window configuration from ``outside'' Edebug |
161c2a25 GM |
981 | (@pxref{Window Configurations}). When you exit Edebug, it restores |
982 | the previous window configuration. | |
73804d4b RS |
983 | |
984 | Emacs redisplays only when it pauses. Usually, when you continue | |
8241495d RS |
985 | execution, the program re-enters Edebug at a breakpoint or after |
986 | stepping, without pausing or reading input in between. In such cases, | |
73804d4b | 987 | Emacs never gets a chance to redisplay the ``outside'' configuration. |
8241495d RS |
988 | Consequently, what you see is the same window configuration as the last |
989 | time Edebug was active, with no interruption. | |
73804d4b RS |
990 | |
991 | Entry to Edebug for displaying something also saves and restores the | |
8241495d RS |
992 | following data (though some of them are deliberately not restored if an |
993 | error or quit signal occurs). | |
73804d4b RS |
994 | |
995 | @itemize @bullet | |
177c0ea7 | 996 | @item |
73804d4b RS |
997 | @cindex current buffer point and mark (Edebug) |
998 | Which buffer is current, and the positions of point and the mark in the | |
999 | current buffer, are saved and restored. | |
1000 | ||
177c0ea7 | 1001 | @item |
73804d4b RS |
1002 | @cindex window configuration (Edebug) |
1003 | The outside window configuration is saved and restored if | |
c5f8bf2d | 1004 | @code{edebug-save-windows} is non-@code{nil} (@pxref{Edebug Options}). |
73804d4b RS |
1005 | |
1006 | The window configuration is not restored on error or quit, but the | |
1007 | outside selected window @emph{is} reselected even on error or quit in | |
1008 | case a @code{save-excursion} is active. If the value of | |
1009 | @code{edebug-save-windows} is a list, only the listed windows are saved | |
1010 | and restored. | |
1011 | ||
1012 | The window start and horizontal scrolling of the source code buffer are | |
1013 | not restored, however, so that the display remains coherent within Edebug. | |
1014 | ||
1015 | @item | |
73804d4b RS |
1016 | The value of point in each displayed buffer is saved and restored if |
1017 | @code{edebug-save-displayed-buffer-points} is non-@code{nil}. | |
1018 | ||
1019 | @item | |
1020 | The variables @code{overlay-arrow-position} and | |
622fa380 | 1021 | @code{overlay-arrow-string} are saved and restored, so you can safely |
73804d4b RS |
1022 | invoke Edebug from the recursive edit elsewhere in the same buffer. |
1023 | ||
177c0ea7 | 1024 | @item |
73804d4b RS |
1025 | @code{cursor-in-echo-area} is locally bound to @code{nil} so that |
1026 | the cursor shows up in the window. | |
1027 | @end itemize | |
1028 | ||
1029 | @node Edebug Recursive Edit | |
1030 | @subsubsection Edebug Recursive Edit | |
1031 | ||
1032 | When Edebug is entered and actually reads commands from the user, it | |
1033 | saves (and later restores) these additional data: | |
1034 | ||
1035 | @itemize @bullet | |
1036 | @item | |
1037 | The current match data. @xref{Match Data}. | |
1038 | ||
1039 | @item | |
342fd6cd | 1040 | The variables @code{last-command}, @code{this-command}, |
84f4a531 | 1041 | @code{last-command-event}, @code{last-input-event}, |
342fd6cd | 1042 | @code{last-event-frame}, @code{last-nonmenu-event}, and |
84f4a531 CY |
1043 | @code{track-mouse}. Commands in Edebug do not affect these variables |
1044 | outside of Edebug. | |
73804d4b | 1045 | |
94da4eb4 RS |
1046 | Executing commands within Edebug can change the key sequence that |
1047 | would be returned by @code{this-command-keys}, and there is no way to | |
1048 | reset the key sequence from Lisp. | |
73804d4b | 1049 | |
87b2d5ff RS |
1050 | Edebug cannot save and restore the value of |
1051 | @code{unread-command-events}. Entering Edebug while this variable has a | |
1052 | nontrivial value can interfere with execution of the program you are | |
1053 | debugging. | |
1054 | ||
73804d4b RS |
1055 | @item |
1056 | Complex commands executed while in Edebug are added to the variable | |
1057 | @code{command-history}. In rare cases this can alter execution. | |
1058 | ||
1059 | @item | |
1060 | Within Edebug, the recursion depth appears one deeper than the recursion | |
1061 | depth outside Edebug. This is not true of the automatically updated | |
1062 | evaluation list window. | |
1063 | ||
1064 | @item | |
1065 | @code{standard-output} and @code{standard-input} are bound to @code{nil} | |
1066 | by the @code{recursive-edit}, but Edebug temporarily restores them during | |
1067 | evaluations. | |
1068 | ||
177c0ea7 | 1069 | @item |
73804d4b RS |
1070 | The state of keyboard macro definition is saved and restored. While |
1071 | Edebug is active, @code{defining-kbd-macro} is bound to | |
1072 | @code{edebug-continue-kbd-macro}. | |
1073 | @end itemize | |
1074 | ||
c5f8bf2d LT |
1075 | @node Edebug and Macros |
1076 | @subsection Edebug and Macros | |
1077 | ||
1078 | To make Edebug properly instrument expressions that call macros, some | |
1079 | extra care is needed. This subsection explains the details. | |
1080 | ||
1081 | @menu | |
1082 | * Instrumenting Macro Calls:: The basic problem. | |
d24880de GM |
1083 | * Specification List:: How to specify complex patterns of evaluation. |
1084 | * Backtracking:: What Edebug does when matching fails. | |
1085 | * Specification Examples:: To help understand specifications. | |
c5f8bf2d LT |
1086 | @end menu |
1087 | ||
73804d4b | 1088 | @node Instrumenting Macro Calls |
c5f8bf2d | 1089 | @subsubsection Instrumenting Macro Calls |
73804d4b | 1090 | |
969fe9b5 RS |
1091 | When Edebug instruments an expression that calls a Lisp macro, it needs |
1092 | additional information about the macro to do the job properly. This is | |
1093 | because there is no a-priori way to tell which subexpressions of the | |
1094 | macro call are forms to be evaluated. (Evaluation may occur explicitly | |
1095 | in the macro body, or when the resulting expansion is evaluated, or any | |
1096 | time later.) | |
1097 | ||
f9350c5c RS |
1098 | Therefore, you must define an Edebug specification for each macro |
1099 | that Edebug will encounter, to explain the format of calls to that | |
a7679889 | 1100 | macro. To do this, add a @code{debug} declaration to the macro |
f9350c5c RS |
1101 | definition. Here is a simple example that shows the specification for |
1102 | the @code{for} example macro (@pxref{Argument Evaluation}). | |
1103 | ||
342fd6cd | 1104 | @smallexample |
f9350c5c RS |
1105 | (defmacro for (var from init to final do &rest body) |
1106 | "Execute a simple \"for\" loop. | |
1107 | For example, (for i from 1 to 10 do (print i))." | |
af5a6df7 | 1108 | (declare (debug (symbolp "from" form "to" form "do" &rest form))) |
f9350c5c | 1109 | ...) |
342fd6cd | 1110 | @end smallexample |
f9350c5c | 1111 | |
89f6de49 | 1112 | The Edebug specification says which parts of a call to the macro are |
622fa380 | 1113 | forms to be evaluated. For simple macros, the specification |
a756468d RS |
1114 | often looks very similar to the formal argument list of the macro |
1115 | definition, but specifications are much more general than macro | |
1116 | arguments. @xref{Defining Macros}, for more explanation of | |
40d2bb40 | 1117 | the @code{declare} form. |
a756468d | 1118 | |
0b021094 GM |
1119 | @c See eg http://debbugs.gnu.org/10577 |
1120 | @c FIXME Maybe there should be an Edebug option to get it to | |
1121 | @c automatically load the entire source file containing the function | |
1122 | @c being instrumented. That would avoid this. | |
1123 | Take care to ensure that the specifications are known to Edebug when | |
1124 | you instrument code. If you are instrumenting a function from a file | |
1125 | that uses @code{eval-when-compile} to require another file containing | |
1126 | macro definitions, you may need to explicitly load that file. | |
1127 | ||
a756468d | 1128 | You can also define an edebug specification for a macro separately |
f9350c5c | 1129 | from the macro definition with @code{def-edebug-spec}. Adding |
a7679889 LK |
1130 | @code{debug} declarations is preferred, and more convenient, for macro |
1131 | definitions in Lisp, but @code{def-edebug-spec} makes it possible to | |
1132 | define Edebug specifications for special forms implemented in C. | |
73804d4b RS |
1133 | |
1134 | @deffn Macro def-edebug-spec macro specification | |
1135 | Specify which expressions of a call to macro @var{macro} are forms to be | |
f9350c5c | 1136 | evaluated. @var{specification} should be the edebug specification. |
c5f8bf2d | 1137 | Neither argument is evaluated. |
73804d4b | 1138 | |
969fe9b5 | 1139 | The @var{macro} argument can actually be any symbol, not just a macro |
73804d4b RS |
1140 | name. |
1141 | @end deffn | |
1142 | ||
73804d4b RS |
1143 | Here is a table of the possibilities for @var{specification} and how each |
1144 | directs processing of arguments. | |
1145 | ||
ec221d13 | 1146 | @table @asis |
73804d4b RS |
1147 | @item @code{t} |
1148 | All arguments are instrumented for evaluation. | |
1149 | ||
1150 | @item @code{0} | |
1151 | None of the arguments is instrumented. | |
1152 | ||
1153 | @item a symbol | |
622fa380 | 1154 | The symbol must have an Edebug specification, which is used instead. |
73804d4b | 1155 | This indirection is repeated until another kind of specification is |
a9f0a989 | 1156 | found. This allows you to inherit the specification from another macro. |
73804d4b RS |
1157 | |
1158 | @item a list | |
1159 | The elements of the list describe the types of the arguments of a | |
1160 | calling form. The possible elements of a specification list are | |
1161 | described in the following sections. | |
1162 | @end table | |
1163 | ||
c5f8bf2d LT |
1164 | If a macro has no Edebug specification, neither through a @code{debug} |
1165 | declaration nor through a @code{def-edebug-spec} call, the variable | |
622fa380 GM |
1166 | @code{edebug-eval-macro-args} comes into play. |
1167 | ||
1168 | @defopt edebug-eval-macro-args | |
1169 | This controls the way Edebug treats macro arguments with no explicit | |
1170 | Edebug specification. If it is @code{nil} (the default), none of the | |
1171 | arguments is instrumented for evaluation. Otherwise, all arguments | |
1172 | are instrumented. | |
1173 | @end defopt | |
73804d4b RS |
1174 | |
1175 | @node Specification List | |
1176 | @subsubsection Specification List | |
1177 | ||
1178 | @cindex Edebug specification list | |
1179 | A @dfn{specification list} is required for an Edebug specification if | |
1180 | some arguments of a macro call are evaluated while others are not. Some | |
1181 | elements in a specification list match one or more arguments, but others | |
1182 | modify the processing of all following elements. The latter, called | |
1183 | @dfn{specification keywords}, are symbols beginning with @samp{&} (such | |
1184 | as @code{&optional}). | |
1185 | ||
650b6d0b | 1186 | A specification list may contain sublists, which match arguments that are |
73804d4b RS |
1187 | themselves lists, or it may contain vectors used for grouping. Sublists |
1188 | and groups thus subdivide the specification list into a hierarchy of | |
969fe9b5 | 1189 | levels. Specification keywords apply only to the remainder of the |
73804d4b RS |
1190 | sublist or group they are contained in. |
1191 | ||
1192 | When a specification list involves alternatives or repetition, matching | |
622fa380 GM |
1193 | it against an actual macro call may require backtracking. For more |
1194 | details, @pxref{Backtracking}. | |
73804d4b RS |
1195 | |
1196 | Edebug specifications provide the power of regular expression matching, | |
1197 | plus some context-free grammar constructs: the matching of sublists with | |
1198 | balanced parentheses, recursive processing of forms, and recursion via | |
1199 | indirect specifications. | |
1200 | ||
1201 | Here's a table of the possible elements of a specification list, with | |
67c1390d LT |
1202 | their meanings (see @ref{Specification Examples}, for the referenced |
1203 | examples): | |
73804d4b RS |
1204 | |
1205 | @table @code | |
1206 | @item sexp | |
1911e6e5 | 1207 | A single unevaluated Lisp object, which is not instrumented. |
a9f0a989 | 1208 | @c an "expression" is not necessarily intended for evaluation. |
73804d4b RS |
1209 | |
1210 | @item form | |
1211 | A single evaluated expression, which is instrumented. | |
1212 | ||
1213 | @item place | |
7c08f8ba | 1214 | A generalized variable. @xref{Generalized Variables}. |
73804d4b RS |
1215 | |
1216 | @item body | |
1217 | Short for @code{&rest form}. See @code{&rest} below. | |
1218 | ||
1219 | @item function-form | |
1220 | A function form: either a quoted function symbol, a quoted lambda | |
1221 | expression, or a form (that should evaluate to a function symbol or | |
1222 | lambda expression). This is useful when an argument that's a lambda | |
1223 | expression might be quoted with @code{quote} rather than | |
1224 | @code{function}, since it instruments the body of the lambda expression | |
1225 | either way. | |
1226 | ||
1227 | @item lambda-expr | |
1228 | A lambda expression with no quoting. | |
1229 | ||
1230 | @item &optional | |
89f6de49 | 1231 | @c @kindex &optional @r{(Edebug)} |
73804d4b | 1232 | All following elements in the specification list are optional; as soon |
177c0ea7 | 1233 | as one does not match, Edebug stops matching at this level. |
73804d4b | 1234 | |
650b6d0b | 1235 | To make just a few elements optional, followed by non-optional elements, |
73804d4b RS |
1236 | use @code{[&optional @var{specs}@dots{}]}. To specify that several |
1237 | elements must all match or none, use @code{&optional | |
67c1390d | 1238 | [@var{specs}@dots{}]}. See the @code{defun} example. |
73804d4b RS |
1239 | |
1240 | @item &rest | |
89f6de49 | 1241 | @c @kindex &rest @r{(Edebug)} |
73804d4b | 1242 | All following elements in the specification list are repeated zero or |
ebc6903b RS |
1243 | more times. In the last repetition, however, it is not a problem if the |
1244 | expression runs out before matching all of the elements of the | |
1245 | specification list. | |
73804d4b RS |
1246 | |
1247 | To repeat only a few elements, use @code{[&rest @var{specs}@dots{}]}. | |
1248 | To specify several elements that must all match on every repetition, use | |
1249 | @code{&rest [@var{specs}@dots{}]}. | |
1250 | ||
1251 | @item &or | |
89f6de49 | 1252 | @c @kindex &or @r{(Edebug)} |
73804d4b RS |
1253 | Each of the following elements in the specification list is an |
1254 | alternative. One of the alternatives must match, or the @code{&or} | |
1255 | specification fails. | |
1256 | ||
1257 | Each list element following @code{&or} is a single alternative. To | |
1258 | group two or more list elements as a single alternative, enclose them in | |
1259 | @code{[@dots{}]}. | |
1260 | ||
1261 | @item ¬ | |
89f6de49 | 1262 | @c @kindex ¬ @r{(Edebug)} |
73804d4b RS |
1263 | Each of the following elements is matched as alternatives as if by using |
1264 | @code{&or}, but if any of them match, the specification fails. If none | |
1265 | of them match, nothing is matched, but the @code{¬} specification | |
1266 | succeeds. | |
1267 | ||
0b021094 GM |
1268 | @c FIXME &key? |
1269 | ||
177c0ea7 | 1270 | @item &define |
89f6de49 | 1271 | @c @kindex &define @r{(Edebug)} |
73804d4b | 1272 | Indicates that the specification is for a defining form. The defining |
a9f0a989 | 1273 | form itself is not instrumented (that is, Edebug does not stop before and |
73804d4b RS |
1274 | after the defining form), but forms inside it typically will be |
1275 | instrumented. The @code{&define} keyword should be the first element in | |
1276 | a list specification. | |
1277 | ||
1278 | @item nil | |
1279 | This is successful when there are no more arguments to match at the | |
1280 | current argument list level; otherwise it fails. See sublist | |
67c1390d | 1281 | specifications and the backquote example. |
73804d4b RS |
1282 | |
1283 | @item gate | |
1284 | @cindex preventing backtracking | |
1285 | No argument is matched but backtracking through the gate is disabled | |
1286 | while matching the remainder of the specifications at this level. This | |
1287 | is primarily used to generate more specific syntax error messages. See | |
67c1390d | 1288 | @ref{Backtracking}, for more details. Also see the @code{let} example. |
73804d4b RS |
1289 | |
1290 | @item @var{other-symbol} | |
1291 | @cindex indirect specifications | |
1292 | Any other symbol in a specification list may be a predicate or an | |
1293 | indirect specification. | |
1294 | ||
1295 | If the symbol has an Edebug specification, this @dfn{indirect | |
1296 | specification} should be either a list specification that is used in | |
1297 | place of the symbol, or a function that is called to process the | |
1298 | arguments. The specification may be defined with @code{def-edebug-spec} | |
622fa380 | 1299 | just as for macros. See the @code{defun} example. |
73804d4b RS |
1300 | |
1301 | Otherwise, the symbol should be a predicate. The predicate is called | |
650b6d0b GM |
1302 | with the argument, and if the predicate returns @code{nil}, the |
1303 | specification fails and the argument is not instrumented. | |
73804d4b | 1304 | |
73804d4b RS |
1305 | Some suitable predicates include @code{symbolp}, @code{integerp}, |
1306 | @code{stringp}, @code{vectorp}, and @code{atom}. | |
73804d4b RS |
1307 | |
1308 | @item [@var{elements}@dots{}] | |
1309 | @cindex [@dots{}] (Edebug) | |
1310 | A vector of elements groups the elements into a single @dfn{group | |
1311 | specification}. Its meaning has nothing to do with vectors. | |
1312 | ||
1313 | @item "@var{string}" | |
1314 | The argument should be a symbol named @var{string}. This specification | |
1315 | is equivalent to the quoted symbol, @code{'@var{symbol}}, where the name | |
1316 | of @var{symbol} is the @var{string}, but the string form is preferred. | |
1317 | ||
73804d4b RS |
1318 | @item (vector @var{elements}@dots{}) |
1319 | The argument should be a vector whose elements must match the | |
67c1390d | 1320 | @var{elements} in the specification. See the backquote example. |
73804d4b RS |
1321 | |
1322 | @item (@var{elements}@dots{}) | |
1323 | Any other list is a @dfn{sublist specification} and the argument must be | |
1324 | a list whose elements match the specification @var{elements}. | |
1325 | ||
1326 | @cindex dotted lists (Edebug) | |
1327 | A sublist specification may be a dotted list and the corresponding list | |
1328 | argument may then be a dotted list. Alternatively, the last @sc{cdr} of a | |
1329 | dotted list specification may be another sublist specification (via a | |
a9f0a989 | 1330 | grouping or an indirect specification, e.g., @code{(spec . [(more |
73804d4b RS |
1331 | specs@dots{})])}) whose elements match the non-dotted list arguments. |
1332 | This is useful in recursive specifications such as in the backquote | |
67c1390d | 1333 | example. Also see the description of a @code{nil} specification |
73804d4b RS |
1334 | above for terminating such recursion. |
1335 | ||
87b2d5ff RS |
1336 | Note that a sublist specification written as @code{(specs . nil)} |
1337 | is equivalent to @code{(specs)}, and @code{(specs . | |
1338 | (sublist-elements@dots{}))} is equivalent to @code{(specs | |
73804d4b RS |
1339 | sublist-elements@dots{})}. |
1340 | @end table | |
1341 | ||
1342 | @c Need to document extensions with &symbol and :symbol | |
1343 | ||
969fe9b5 | 1344 | Here is a list of additional specifications that may appear only after |
67c1390d | 1345 | @code{&define}. See the @code{defun} example. |
73804d4b RS |
1346 | |
1347 | @table @code | |
1348 | @item name | |
177c0ea7 | 1349 | The argument, a symbol, is the name of the defining form. |
73804d4b RS |
1350 | |
1351 | A defining form is not required to have a name field; and it may have | |
1352 | multiple name fields. | |
1353 | ||
1354 | @item :name | |
1355 | This construct does not actually match an argument. The element | |
1356 | following @code{:name} should be a symbol; it is used as an additional | |
1357 | name component for the definition. You can use this to add a unique, | |
1358 | static component to the name of the definition. It may be used more | |
1359 | than once. | |
1360 | ||
1361 | @item arg | |
1362 | The argument, a symbol, is the name of an argument of the defining form. | |
a9f0a989 | 1363 | However, lambda-list keywords (symbols starting with @samp{&}) |
87b2d5ff | 1364 | are not allowed. |
73804d4b RS |
1365 | |
1366 | @item lambda-list | |
1367 | @cindex lambda-list (Edebug) | |
1368 | This matches a lambda list---the argument list of a lambda expression. | |
73804d4b RS |
1369 | |
1370 | @item def-body | |
1371 | The argument is the body of code in a definition. This is like | |
1372 | @code{body}, described above, but a definition body must be instrumented | |
1373 | with a different Edebug call that looks up information associated with | |
1374 | the definition. Use @code{def-body} for the highest level list of forms | |
1375 | within the definition. | |
1376 | ||
1377 | @item def-form | |
1378 | The argument is a single, highest-level form in a definition. This is | |
622fa380 | 1379 | like @code{def-body}, except it is used to match a single form rather than |
73804d4b RS |
1380 | a list of forms. As a special case, @code{def-form} also means that |
1381 | tracing information is not output when the form is executed. See the | |
67c1390d | 1382 | @code{interactive} example. |
73804d4b RS |
1383 | @end table |
1384 | ||
1385 | @node Backtracking | |
969fe9b5 | 1386 | @subsubsection Backtracking in Specifications |
73804d4b RS |
1387 | |
1388 | @cindex backtracking | |
1389 | @cindex syntax error (Edebug) | |
1390 | If a specification fails to match at some point, this does not | |
1391 | necessarily mean a syntax error will be signaled; instead, | |
1392 | @dfn{backtracking} will take place until all alternatives have been | |
1393 | exhausted. Eventually every element of the argument list must be | |
1394 | matched by some element in the specification, and every required element | |
1395 | in the specification must match some argument. | |
177c0ea7 | 1396 | |
a9f0a989 | 1397 | When a syntax error is detected, it might not be reported until much |
622fa380 | 1398 | later, after higher-level alternatives have been exhausted, and with the |
a9f0a989 RS |
1399 | point positioned further from the real error. But if backtracking is |
1400 | disabled when an error occurs, it can be reported immediately. Note | |
1401 | that backtracking is also reenabled automatically in several situations; | |
622fa380 GM |
1402 | when a new alternative is established by @code{&optional}, |
1403 | @code{&rest}, or @code{&or}, or at the start of processing a sublist, | |
1404 | group, or indirect specification. The effect of enabling or disabling | |
1405 | backtracking is limited to the remainder of the level currently being | |
1406 | processed and lower levels. | |
a9f0a989 RS |
1407 | |
1408 | Backtracking is disabled while matching any of the | |
1409 | form specifications (that is, @code{form}, @code{body}, @code{def-form}, and | |
73804d4b RS |
1410 | @code{def-body}). These specifications will match any form so any error |
1411 | must be in the form itself rather than at a higher level. | |
1412 | ||
a9f0a989 | 1413 | Backtracking is also disabled after successfully matching a quoted |
73804d4b | 1414 | symbol or string specification, since this usually indicates a |
a9f0a989 | 1415 | recognized construct. But if you have a set of alternative constructs that |
73804d4b RS |
1416 | all begin with the same symbol, you can usually work around this |
1417 | constraint by factoring the symbol out of the alternatives, e.g., | |
1418 | @code{["foo" &or [first case] [second case] ...]}. | |
1419 | ||
3e7274ae | 1420 | Most needs are satisfied by these two ways that backtracking is |
a9f0a989 RS |
1421 | automatically disabled, but occasionally it is useful to explicitly |
1422 | disable backtracking by using the @code{gate} specification. This is | |
1423 | useful when you know that no higher alternatives could apply. See the | |
1424 | example of the @code{let} specification. | |
73804d4b | 1425 | |
73804d4b RS |
1426 | @node Specification Examples |
1427 | @subsubsection Specification Examples | |
1428 | ||
1429 | It may be easier to understand Edebug specifications by studying | |
1430 | the examples provided here. | |
1431 | ||
1432 | A @code{let} special form has a sequence of bindings and a body. Each | |
1433 | of the bindings is either a symbol or a sublist with a symbol and | |
a9f0a989 | 1434 | optional expression. In the specification below, notice the @code{gate} |
73804d4b RS |
1435 | inside of the sublist to prevent backtracking once a sublist is found. |
1436 | ||
0b021094 GM |
1437 | @ignore |
1438 | @c FIXME? The actual definition in edebug.el looks like this (and always | |
1439 | @c has AFAICS). In fact, nothing in edebug.el uses gate. So maybe | |
1440 | @c this is just an example for illustration? | |
1441 | (def-edebug-spec let | |
1442 | ((&rest | |
1443 | &or (symbolp &optional form) symbolp) | |
1444 | body)) | |
1445 | @end ignore | |
73804d4b RS |
1446 | @example |
1447 | (def-edebug-spec let | |
1448 | ((&rest | |
1449 | &or symbolp (gate symbolp &optional form)) | |
1450 | body)) | |
1451 | @end example | |
1452 | ||
622fa380 GM |
1453 | Edebug uses the following specifications for @code{defun} and the |
1454 | associated argument list and @code{interactive} specifications. It is | |
1455 | necessary to handle interactive forms specially since an expression | |
1456 | argument is actually evaluated outside of the function body. (The | |
1457 | specification for @code{defmacro} is very similar to that for | |
1458 | @code{defun}, but allows for the @code{declare} statement.) | |
73804d4b | 1459 | |
87b2d5ff | 1460 | @smallexample |
177c0ea7 JB |
1461 | (def-edebug-spec defun |
1462 | (&define name lambda-list | |
87b2d5ff | 1463 | [&optional stringp] ; @r{Match the doc string, if present.} |
73804d4b RS |
1464 | [&optional ("interactive" interactive)] |
1465 | def-body)) | |
1466 | ||
1467 | (def-edebug-spec lambda-list | |
1468 | (([&rest arg] | |
1469 | [&optional ["&optional" arg &rest arg]] | |
1470 | &optional ["&rest" arg] | |
1471 | ))) | |
1472 | ||
1473 | (def-edebug-spec interactive | |
1474 | (&optional &or stringp def-form)) ; @r{Notice: @code{def-form}} | |
87b2d5ff | 1475 | @end smallexample |
73804d4b RS |
1476 | |
1477 | The specification for backquote below illustrates how to match | |
1478 | dotted lists and use @code{nil} to terminate recursion. It also | |
1479 | illustrates how components of a vector may be matched. (The actual | |
622fa380 GM |
1480 | specification defined by Edebug is a little different, and does not |
1481 | support dotted lists because doing so causes very deep recursion that | |
1482 | could fail.) | |
73804d4b | 1483 | |
87b2d5ff | 1484 | @smallexample |
622fa380 | 1485 | (def-edebug-spec \` (backquote-form)) ; @r{Alias just for clarity.} |
73804d4b RS |
1486 | |
1487 | (def-edebug-spec backquote-form | |
1488 | (&or ([&or "," ",@@"] &or ("quote" backquote-form) form) | |
1489 | (backquote-form . [&or nil backquote-form]) | |
1490 | (vector &rest backquote-form) | |
1491 | sexp)) | |
87b2d5ff | 1492 | @end smallexample |
73804d4b RS |
1493 | |
1494 | ||
1495 | @node Edebug Options | |
1496 | @subsection Edebug Options | |
1497 | ||
1498 | These options affect the behavior of Edebug: | |
622fa380 GM |
1499 | @c Previously defopt'd: |
1500 | @c edebug-sit-for-seconds, edebug-print-length, edebug-print-level | |
1501 | @c edebug-print-circle, edebug-eval-macro-args | |
73804d4b RS |
1502 | |
1503 | @defopt edebug-setup-hook | |
1504 | Functions to call before Edebug is used. Each time it is set to a new | |
1505 | value, Edebug will call those functions once and then | |
650b6d0b GM |
1506 | reset @code{edebug-setup-hook} to @code{nil}. You could use this to |
1507 | load up Edebug specifications associated with a package you are using, | |
73804d4b RS |
1508 | but only when you also use Edebug. |
1509 | @xref{Instrumenting}. | |
1510 | @end defopt | |
1511 | ||
1512 | @defopt edebug-all-defs | |
1513 | If this is non-@code{nil}, normal evaluation of defining forms such as | |
1514 | @code{defun} and @code{defmacro} instruments them for Edebug. This | |
87b2d5ff RS |
1515 | applies to @code{eval-defun}, @code{eval-region}, @code{eval-buffer}, |
1516 | and @code{eval-current-buffer}. | |
1517 | ||
1518 | Use the command @kbd{M-x edebug-all-defs} to toggle the value of this | |
1519 | option. @xref{Instrumenting}. | |
73804d4b RS |
1520 | @end defopt |
1521 | ||
1522 | @defopt edebug-all-forms | |
87b2d5ff RS |
1523 | If this is non-@code{nil}, the commands @code{eval-defun}, |
1524 | @code{eval-region}, @code{eval-buffer}, and @code{eval-current-buffer} | |
1525 | instrument all forms, even those that don't define anything. | |
1526 | This doesn't apply to loading or evaluations in the minibuffer. | |
73804d4b RS |
1527 | |
1528 | Use the command @kbd{M-x edebug-all-forms} to toggle the value of this | |
87b2d5ff | 1529 | option. @xref{Instrumenting}. |
73804d4b RS |
1530 | @end defopt |
1531 | ||
1532 | @defopt edebug-save-windows | |
1533 | If this is non-@code{nil}, Edebug saves and restores the window | |
1534 | configuration. That takes some time, so if your program does not care | |
1535 | what happens to the window configurations, it is better to set this | |
1536 | variable to @code{nil}. | |
1537 | ||
1538 | If the value is a list, only the listed windows are saved and | |
177c0ea7 | 1539 | restored. |
73804d4b RS |
1540 | |
1541 | You can use the @kbd{W} command in Edebug to change this variable | |
1542 | interactively. @xref{Edebug Display Update}. | |
1543 | @end defopt | |
1544 | ||
1545 | @defopt edebug-save-displayed-buffer-points | |
87b2d5ff RS |
1546 | If this is non-@code{nil}, Edebug saves and restores point in all |
1547 | displayed buffers. | |
73804d4b RS |
1548 | |
1549 | Saving and restoring point in other buffers is necessary if you are | |
622fa380 | 1550 | debugging code that changes the point of a buffer that is displayed in |
73804d4b | 1551 | a non-selected window. If Edebug or the user then selects the window, |
87b2d5ff | 1552 | point in that buffer will move to the window's value of point. |
73804d4b RS |
1553 | |
1554 | Saving and restoring point in all buffers is expensive, since it | |
1555 | requires selecting each window twice, so enable this only if you need | |
1556 | it. @xref{Edebug Display Update}. | |
1557 | @end defopt | |
1558 | ||
1559 | @defopt edebug-initial-mode | |
1560 | If this variable is non-@code{nil}, it specifies the initial execution | |
1561 | mode for Edebug when it is first activated. Possible values are | |
1562 | @code{step}, @code{next}, @code{go}, @code{Go-nonstop}, @code{trace}, | |
1563 | @code{Trace-fast}, @code{continue}, and @code{Continue-fast}. | |
1564 | ||
177c0ea7 | 1565 | The default value is @code{step}. |
73804d4b RS |
1566 | @xref{Edebug Execution Modes}. |
1567 | @end defopt | |
1568 | ||
1569 | @defopt edebug-trace | |
42995636 | 1570 | If this is non-@code{nil}, trace each function entry and exit. |
2bb0eca1 | 1571 | Tracing output is displayed in a buffer named @file{*edebug-trace*}, one |
177c0ea7 | 1572 | function entry or exit per line, indented by the recursion level. |
73804d4b | 1573 | |
a9f0a989 | 1574 | Also see @code{edebug-tracing}, in @ref{Trace Buffer}. |
73804d4b RS |
1575 | @end defopt |
1576 | ||
177c0ea7 | 1577 | @defopt edebug-test-coverage |
73804d4b | 1578 | If non-@code{nil}, Edebug tests coverage of all expressions debugged. |
73804d4b RS |
1579 | @xref{Coverage Testing}. |
1580 | @end defopt | |
1581 | ||
177c0ea7 | 1582 | @defopt edebug-continue-kbd-macro |
73804d4b RS |
1583 | If non-@code{nil}, continue defining or executing any keyboard macro |
1584 | that is executing outside of Edebug. Use this with caution since it is not | |
1585 | debugged. | |
1586 | @xref{Edebug Execution Modes}. | |
1587 | @end defopt | |
1588 | ||
0b021094 GM |
1589 | @defopt edebug-unwrap-results |
1590 | If non-@code{nil}, Edebug tries to remove any of its own | |
1591 | instrumentation when showing the results of expressions. This is | |
1592 | relevant when debugging macros where the results of expressions are | |
1593 | themselves instrumented expressions. As a very artificial example, | |
1594 | suppose that the example function @code{fac} has been instrumented, | |
1595 | and consider a macro of the form: | |
1596 | ||
1597 | @c FIXME find a less silly example. | |
1598 | @smallexample | |
1599 | (defmacro test () "Edebug example." | |
1600 | (if (symbol-function 'fac) | |
1601 | @dots{})) | |
1602 | @end smallexample | |
1603 | ||
1604 | If you instrument the @code{test} macro and step through it, then by | |
1605 | default the result of the @code{symbol-function} call has numerous | |
1606 | @code{edebug-after} and @code{edebug-before} forms, which can make it | |
1607 | difficult to see the ``actual'' result. If | |
1608 | @code{edebug-unwrap-results} is non-@code{nil}, Edebug tries to remove | |
1609 | these forms from the result. | |
1610 | @end defopt | |
622fa380 | 1611 | |
73804d4b RS |
1612 | @defopt edebug-on-error |
1613 | Edebug binds @code{debug-on-error} to this value, if | |
1614 | @code{debug-on-error} was previously @code{nil}. @xref{Trapping | |
1615 | Errors}. | |
1616 | @end defopt | |
1617 | ||
1618 | @defopt edebug-on-quit | |
1619 | Edebug binds @code{debug-on-quit} to this value, if | |
1620 | @code{debug-on-quit} was previously @code{nil}. @xref{Trapping | |
1621 | Errors}. | |
1622 | @end defopt | |
1623 | ||
1624 | If you change the values of @code{edebug-on-error} or | |
1625 | @code{edebug-on-quit} while Edebug is active, their values won't be used | |
87b2d5ff RS |
1626 | until the @emph{next} time Edebug is invoked via a new command. |
1627 | @c Not necessarily a deeper command level. | |
1628 | @c A new command is not precisely true, but that is close enough -- dan | |
73804d4b RS |
1629 | |
1630 | @defopt edebug-global-break-condition | |
9a8dc0d3 RS |
1631 | If non-@code{nil}, an expression to test for at every stop point. If |
1632 | the result is non-@code{nil}, then break. Errors are ignored. | |
73804d4b RS |
1633 | @xref{Global Break Condition}. |
1634 | @end defopt |