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73804d4b | 1 | @comment -*-texinfo-*- |
969fe9b5 | 2 | @c This is part of the GNU Emacs Lisp Reference Manual. |
ab422c4d PE |
3 | @c Copyright (C) 1992-1994, 1998-1999, 2001-2013 Free Software |
4 | @c Foundation, Inc. | |
969fe9b5 | 5 | @c See the file elisp.texi for copying conditions. |
73804d4b | 6 | |
177c0ea7 JB |
7 | @c This file can also be used by an independent Edebug User |
8 | @c Manual in which case the Edebug node below should be used | |
73804d4b RS |
9 | @c with the following links to the Bugs section and to the top level: |
10 | ||
11 | @c , Bugs and Todo List, Top, Top | |
12 | ||
ecc6530d | 13 | @node Edebug |
73804d4b | 14 | @section Edebug |
77bf576c | 15 | @cindex Edebug debugging facility |
73804d4b | 16 | |
622fa380 | 17 | Edebug is a source-level debugger for Emacs Lisp programs, with which |
73804d4b RS |
18 | you can: |
19 | ||
20 | @itemize @bullet | |
21 | @item | |
22 | Step through evaluation, stopping before and after each expression. | |
23 | ||
24 | @item | |
25 | Set conditional or unconditional breakpoints. | |
26 | ||
27 | @item | |
28 | Stop when a specified condition is true (the global break event). | |
29 | ||
30 | @item | |
31 | Trace slow or fast, stopping briefly at each stop point, or | |
32 | at each breakpoint. | |
33 | ||
34 | @item | |
35 | Display expression results and evaluate expressions as if outside of | |
36 | Edebug. | |
37 | ||
177c0ea7 | 38 | @item |
a9f0a989 | 39 | Automatically re-evaluate a list of expressions and |
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40 | display their results each time Edebug updates the display. |
41 | ||
42 | @item | |
622fa380 | 43 | Output trace information on function calls and returns. |
73804d4b RS |
44 | |
45 | @item | |
46 | Stop when an error occurs. | |
47 | ||
48 | @item | |
49 | Display a backtrace, omitting Edebug's own frames. | |
50 | ||
51 | @item | |
52 | Specify argument evaluation for macros and defining forms. | |
53 | ||
54 | @item | |
55 | Obtain rudimentary coverage testing and frequency counts. | |
56 | @end itemize | |
57 | ||
58 | The first three sections below should tell you enough about Edebug to | |
622fa380 | 59 | start using it. |
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60 | |
61 | @menu | |
d24880de GM |
62 | * Using Edebug:: Introduction to use of Edebug. |
63 | * Instrumenting:: You must instrument your code | |
64 | in order to debug it with Edebug. | |
73804d4b | 65 | * Modes: Edebug Execution Modes. Execution modes, stopping more or less often. |
d24880de GM |
66 | * Jumping:: Commands to jump to a specified place. |
67 | * Misc: Edebug Misc. Miscellaneous commands. | |
c5f8bf2d | 68 | * Breaks:: Setting breakpoints to make the program stop. |
d24880de GM |
69 | * Trapping Errors:: Trapping errors with Edebug. |
70 | * Views: Edebug Views. Views inside and outside of Edebug. | |
71 | * Eval: Edebug Eval. Evaluating expressions within Edebug. | |
72 | * Eval List:: Expressions whose values are displayed | |
73 | each time you enter Edebug. | |
74 | * Printing in Edebug:: Customization of printing. | |
75 | * Trace Buffer:: How to produce trace output in a buffer. | |
76 | * Coverage Testing:: How to test evaluation coverage. | |
77 | * The Outside Context:: Data that Edebug saves and restores. | |
78 | * Edebug and Macros:: Specifying how to handle macro calls. | |
79 | * Options: Edebug Options. Option variables for customizing Edebug. | |
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80 | @end menu |
81 | ||
82 | @node Using Edebug | |
83 | @subsection Using Edebug | |
84 | ||
85 | To debug a Lisp program with Edebug, you must first @dfn{instrument} | |
86 | the Lisp code that you want to debug. A simple way to do this is to | |
87 | first move point into the definition of a function or macro and then do | |
88 | @kbd{C-u C-M-x} (@code{eval-defun} with a prefix argument). See | |
89 | @ref{Instrumenting}, for alternative ways to instrument code. | |
90 | ||
91 | Once a function is instrumented, any call to the function activates | |
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92 | Edebug. Depending on which Edebug execution mode you have selected, |
93 | activating Edebug may stop execution and let you step through the | |
94 | function, or it may update the display and continue execution while | |
95 | checking for debugging commands. The default execution mode is step, | |
96 | which stops execution. @xref{Edebug Execution Modes}. | |
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97 | |
98 | Within Edebug, you normally view an Emacs buffer showing the source of | |
99 | the Lisp code you are debugging. This is referred to as the @dfn{source | |
2bdedac1 | 100 | code buffer}, and it is temporarily read-only. |
73804d4b | 101 | |
2634c6e4 | 102 | An arrow in the left fringe indicates the line where the function is |
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103 | executing. Point initially shows where within the line the function is |
104 | executing, but this ceases to be true if you move point yourself. | |
105 | ||
106 | If you instrument the definition of @code{fac} (shown below) and then | |
8241495d RS |
107 | execute @code{(fac 3)}, here is what you would normally see. Point is |
108 | at the open-parenthesis before @code{if}. | |
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109 | |
110 | @example | |
111 | (defun fac (n) | |
112 | =>@point{}(if (< 0 n) | |
113 | (* n (fac (1- n))) | |
114 | 1)) | |
115 | @end example | |
116 | ||
117 | @cindex stop points | |
118 | The places within a function where Edebug can stop execution are called | |
119 | @dfn{stop points}. These occur both before and after each subexpression | |
177c0ea7 | 120 | that is a list, and also after each variable reference. |
8241495d | 121 | Here we use periods to show the stop points in the function |
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122 | @code{fac}: |
123 | ||
124 | @example | |
125 | (defun fac (n) | |
126 | .(if .(< 0 n.). | |
b180eac2 | 127 | .(* n. .(fac .(1- n.).).). |
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128 | 1).) |
129 | @end example | |
130 | ||
131 | The special commands of Edebug are available in the source code buffer | |
132 | in addition to the commands of Emacs Lisp mode. For example, you can | |
133 | type the Edebug command @key{SPC} to execute until the next stop point. | |
134 | If you type @key{SPC} once after entry to @code{fac}, here is the | |
135 | display you will see: | |
136 | ||
137 | @example | |
138 | (defun fac (n) | |
139 | =>(if @point{}(< 0 n) | |
140 | (* n (fac (1- n))) | |
141 | 1)) | |
142 | @end example | |
143 | ||
144 | When Edebug stops execution after an expression, it displays the | |
177c0ea7 | 145 | expression's value in the echo area. |
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146 | |
147 | Other frequently used commands are @kbd{b} to set a breakpoint at a stop | |
148 | point, @kbd{g} to execute until a breakpoint is reached, and @kbd{q} to | |
149 | exit Edebug and return to the top-level command loop. Type @kbd{?} to | |
150 | display a list of all Edebug commands. | |
151 | ||
152 | @node Instrumenting | |
153 | @subsection Instrumenting for Edebug | |
287d7455 | 154 | @cindex instrumenting for Edebug |
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155 | |
156 | In order to use Edebug to debug Lisp code, you must first | |
157 | @dfn{instrument} the code. Instrumenting code inserts additional code | |
87b2d5ff | 158 | into it, to invoke Edebug at the proper places. |
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159 | |
160 | @kindex C-M-x | |
161 | @findex eval-defun (Edebug) | |
2634c6e4 RS |
162 | When you invoke command @kbd{C-M-x} (@code{eval-defun}) with a |
163 | prefix argument on a function definition, it instruments the | |
164 | definition before evaluating it. (This does not modify the source | |
165 | code itself.) If the variable @code{edebug-all-defs} is | |
166 | non-@code{nil}, that inverts the meaning of the prefix argument: in | |
167 | this case, @kbd{C-M-x} instruments the definition @emph{unless} it has | |
168 | a prefix argument. The default value of @code{edebug-all-defs} is | |
169 | @code{nil}. The command @kbd{M-x edebug-all-defs} toggles the value | |
170 | of the variable @code{edebug-all-defs}. | |
73804d4b | 171 | |
969fe9b5 | 172 | @findex eval-region @r{(Edebug)} |
d8ca18c7 | 173 | @findex eval-buffer @r{(Edebug)} |
969fe9b5 | 174 | @findex eval-current-buffer @r{(Edebug)} |
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175 | If @code{edebug-all-defs} is non-@code{nil}, then the commands |
176 | @code{eval-region}, @code{eval-current-buffer}, and @code{eval-buffer} | |
177 | also instrument any definitions they evaluate. Similarly, | |
178 | @code{edebug-all-forms} controls whether @code{eval-region} should | |
179 | instrument @emph{any} form, even non-defining forms. This doesn't apply | |
180 | to loading or evaluations in the minibuffer. The command @kbd{M-x | |
181 | edebug-all-forms} toggles this option. | |
182 | ||
183 | @findex edebug-eval-top-level-form | |
287d7455 | 184 | @findex edebug-defun |
969fe9b5 | 185 | Another command, @kbd{M-x edebug-eval-top-level-form}, is available to |
f9f59935 RS |
186 | instrument any top-level form regardless of the values of |
187 | @code{edebug-all-defs} and @code{edebug-all-forms}. | |
287d7455 | 188 | @code{edebug-defun} is an alias for @code{edebug-eval-top-level-form}. |
73804d4b | 189 | |
969fe9b5 | 190 | While Edebug is active, the command @kbd{I} |
73804d4b | 191 | (@code{edebug-instrument-callee}) instruments the definition of the |
da0bbbc4 | 192 | function or macro called by the list form after point, if it is not already |
73804d4b | 193 | instrumented. This is possible only if Edebug knows where to find the |
622fa380 | 194 | source for that function; for this reason, after loading Edebug, |
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195 | @code{eval-region} records the position of every definition it |
196 | evaluates, even if not instrumenting it. See also the @kbd{i} command | |
197 | (@pxref{Jumping}), which steps into the call after instrumenting the | |
198 | function. | |
73804d4b | 199 | |
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200 | Edebug knows how to instrument all the standard special forms, |
201 | @code{interactive} forms with an expression argument, anonymous lambda | |
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202 | expressions, and other defining forms. However, Edebug cannot determine |
203 | on its own what a user-defined macro will do with the arguments of a | |
67c1390d | 204 | macro call, so you must provide that information using Edebug |
622fa380 | 205 | specifications; for details, @pxref{Edebug and Macros}. |
73804d4b | 206 | |
969fe9b5 RS |
207 | When Edebug is about to instrument code for the first time in a |
208 | session, it runs the hook @code{edebug-setup-hook}, then sets it to | |
8241495d | 209 | @code{nil}. You can use this to load Edebug specifications |
67c1390d | 210 | associated with a package you are using, but only when you use Edebug. |
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211 | |
212 | @findex eval-expression @r{(Edebug)} | |
a9f0a989 | 213 | To remove instrumentation from a definition, simply re-evaluate its |
73804d4b | 214 | definition in a way that does not instrument. There are two ways of |
87b2d5ff | 215 | evaluating forms that never instrument them: from a file with |
73804d4b | 216 | @code{load}, and from the minibuffer with @code{eval-expression} |
bfe721d1 | 217 | (@kbd{M-:}). |
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218 | |
219 | If Edebug detects a syntax error while instrumenting, it leaves point | |
220 | at the erroneous code and signals an @code{invalid-read-syntax} error. | |
f1224267 | 221 | @c FIXME? I can't see that it "leaves point at the erroneous code". |
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222 | |
223 | @xref{Edebug Eval}, for other evaluation functions available | |
224 | inside of Edebug. | |
225 | ||
226 | @node Edebug Execution Modes | |
227 | @subsection Edebug Execution Modes | |
228 | ||
229 | @cindex Edebug execution modes | |
230 | Edebug supports several execution modes for running the program you are | |
231 | debugging. We call these alternatives @dfn{Edebug execution modes}; do | |
87b2d5ff | 232 | not confuse them with major or minor modes. The current Edebug execution mode |
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233 | determines how far Edebug continues execution before stopping---whether |
234 | it stops at each stop point, or continues to the next breakpoint, for | |
235 | example---and how much Edebug displays the progress of the evaluation | |
236 | before it stops. | |
237 | ||
238 | Normally, you specify the Edebug execution mode by typing a command to | |
239 | continue the program in a certain mode. Here is a table of these | |
8241495d | 240 | commands; all except for @kbd{S} resume execution of the program, at |
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241 | least for a certain distance. |
242 | ||
243 | @table @kbd | |
244 | @item S | |
8241495d | 245 | Stop: don't execute any more of the program, but wait for more |
73804d4b | 246 | Edebug commands (@code{edebug-stop}). |
f1224267 | 247 | @c FIXME Does not work. http://debbugs.gnu.org/9764 |
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248 | |
249 | @item @key{SPC} | |
250 | Step: stop at the next stop point encountered (@code{edebug-step-mode}). | |
251 | ||
252 | @item n | |
253 | Next: stop at the next stop point encountered after an expression | |
254 | (@code{edebug-next-mode}). Also see @code{edebug-forward-sexp} in | |
c5f8bf2d | 255 | @ref{Jumping}. |
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256 | |
257 | @item t | |
89f6de49 RS |
258 | Trace: pause (normally one second) at each Edebug stop point |
259 | (@code{edebug-trace-mode}). | |
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260 | |
261 | @item T | |
262 | Rapid trace: update the display at each stop point, but don't actually | |
263 | pause (@code{edebug-Trace-fast-mode}). | |
264 | ||
265 | @item g | |
266 | Go: run until the next breakpoint (@code{edebug-go-mode}). @xref{Breakpoints}. | |
267 | ||
268 | @item c | |
269 | Continue: pause one second at each breakpoint, and then continue | |
270 | (@code{edebug-continue-mode}). | |
271 | ||
272 | @item C | |
273 | Rapid continue: move point to each breakpoint, but don't pause | |
274 | (@code{edebug-Continue-fast-mode}). | |
275 | ||
276 | @item G | |
277 | Go non-stop: ignore breakpoints (@code{edebug-Go-nonstop-mode}). You | |
278 | can still stop the program by typing @kbd{S}, or any editing command. | |
279 | @end table | |
280 | ||
281 | In general, the execution modes earlier in the above list run the | |
87b2d5ff | 282 | program more slowly or stop sooner than the modes later in the list. |
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283 | |
284 | While executing or tracing, you can interrupt the execution by typing | |
285 | any Edebug command. Edebug stops the program at the next stop point and | |
87b2d5ff RS |
286 | then executes the command you typed. For example, typing @kbd{t} during |
287 | execution switches to trace mode at the next stop point. You can use | |
288 | @kbd{S} to stop execution without doing anything else. | |
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289 | |
290 | If your function happens to read input, a character you type intending | |
291 | to interrupt execution may be read by the function instead. You can | |
292 | avoid such unintended results by paying attention to when your program | |
293 | wants input. | |
294 | ||
295 | @cindex keyboard macros (Edebug) | |
296 | Keyboard macros containing the commands in this section do not | |
297 | completely work: exiting from Edebug, to resume the program, loses track | |
298 | of the keyboard macro. This is not easy to fix. Also, defining or | |
299 | executing a keyboard macro outside of Edebug does not affect commands | |
8241495d | 300 | inside Edebug. This is usually an advantage. See also the |
622fa380 | 301 | @code{edebug-continue-kbd-macro} option in @ref{Edebug Options}. |
73804d4b | 302 | |
2634c6e4 | 303 | When you enter a new Edebug level, the initial execution mode comes |
622fa380 GM |
304 | from the value of the variable @code{edebug-initial-mode} |
305 | (@pxref{Edebug Options}). By default, this specifies step mode. Note | |
2634c6e4 RS |
306 | that you may reenter the same Edebug level several times if, for |
307 | example, an instrumented function is called several times from one | |
308 | command. | |
73804d4b | 309 | |
89f6de49 RS |
310 | @defopt edebug-sit-for-seconds |
311 | This option specifies how many seconds to wait between execution steps | |
622fa380 | 312 | in trace mode or continue mode. The default is 1 second. |
b52a26fb | 313 | @end defopt |
73804d4b RS |
314 | |
315 | @node Jumping | |
316 | @subsection Jumping | |
317 | ||
318 | The commands described in this section execute until they reach a | |
319 | specified location. All except @kbd{i} make a temporary breakpoint to | |
320 | establish the place to stop, then switch to go mode. Any other | |
321 | breakpoint reached before the intended stop point will also stop | |
322 | execution. @xref{Breakpoints}, for the details on breakpoints. | |
323 | ||
324 | These commands may fail to work as expected in case of nonlocal exit, | |
8241495d RS |
325 | as that can bypass the temporary breakpoint where you expected the |
326 | program to stop. | |
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327 | |
328 | @table @kbd | |
329 | @item h | |
330 | Proceed to the stop point near where point is (@code{edebug-goto-here}). | |
331 | ||
332 | @item f | |
342fd6cd | 333 | Run the program for one expression |
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334 | (@code{edebug-forward-sexp}). |
335 | ||
336 | @item o | |
622fa380 | 337 | Run the program until the end of the containing sexp (@code{edebug-step-out}). |
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338 | |
339 | @item i | |
f1224267 GM |
340 | Step into the function or macro called by the form after point |
341 | (@code{edebug-step-in}). | |
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342 | @end table |
343 | ||
c5f8bf2d LT |
344 | The @kbd{h} command proceeds to the stop point at or after the current |
345 | location of point, using a temporary breakpoint. | |
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346 | |
347 | The @kbd{f} command runs the program forward over one expression. More | |
348 | precisely, it sets a temporary breakpoint at the position that | |
622fa380 GM |
349 | @code{forward-sexp} would reach, then executes in go mode so that |
350 | the program will stop at breakpoints. | |
73804d4b RS |
351 | |
352 | With a prefix argument @var{n}, the temporary breakpoint is placed | |
353 | @var{n} sexps beyond point. If the containing list ends before @var{n} | |
354 | more elements, then the place to stop is after the containing | |
355 | expression. | |
356 | ||
622fa380 GM |
357 | You must check that the position @code{forward-sexp} finds is a place |
358 | that the program will really get to. In @code{cond}, for example, | |
359 | this may not be true. | |
73804d4b | 360 | |
8241495d RS |
361 | For flexibility, the @kbd{f} command does @code{forward-sexp} starting |
362 | at point, rather than at the stop point. If you want to execute one | |
622fa380 GM |
363 | expression @emph{from the current stop point}, first type @kbd{w} |
364 | (@code{edebug-where}) to move point there, and then type @kbd{f}. | |
73804d4b RS |
365 | |
366 | The @kbd{o} command continues ``out of'' an expression. It places a | |
367 | temporary breakpoint at the end of the sexp containing point. If the | |
87b2d5ff RS |
368 | containing sexp is a function definition itself, @kbd{o} continues until |
369 | just before the last sexp in the definition. If that is where you are | |
370 | now, it returns from the function and then stops. In other words, this | |
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371 | command does not exit the currently executing function unless you are |
372 | positioned after the last sexp. | |
373 | ||
374 | The @kbd{i} command steps into the function or macro called by the list | |
87b2d5ff RS |
375 | form after point, and stops at its first stop point. Note that the form |
376 | need not be the one about to be evaluated. But if the form is a | |
377 | function call about to be evaluated, remember to use this command before | |
378 | any of the arguments are evaluated, since otherwise it will be too late. | |
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379 | |
380 | The @kbd{i} command instruments the function or macro it's supposed to | |
381 | step into, if it isn't instrumented already. This is convenient, but keep | |
382 | in mind that the function or macro remains instrumented unless you explicitly | |
383 | arrange to deinstrument it. | |
384 | ||
385 | @node Edebug Misc | |
386 | @subsection Miscellaneous Edebug Commands | |
387 | ||
388 | Some miscellaneous Edebug commands are described here. | |
389 | ||
390 | @table @kbd | |
391 | @item ? | |
392 | Display the help message for Edebug (@code{edebug-help}). | |
393 | ||
394 | @item C-] | |
395 | Abort one level back to the previous command level | |
396 | (@code{abort-recursive-edit}). | |
397 | ||
398 | @item q | |
399 | Return to the top level editor command loop (@code{top-level}). This | |
400 | exits all recursive editing levels, including all levels of Edebug | |
401 | activity. However, instrumented code protected with | |
402 | @code{unwind-protect} or @code{condition-case} forms may resume | |
403 | debugging. | |
404 | ||
405 | @item Q | |
8241495d | 406 | Like @kbd{q}, but don't stop even for protected code |
622fa380 | 407 | (@code{edebug-top-level-nonstop}). |
73804d4b RS |
408 | |
409 | @item r | |
410 | Redisplay the most recently known expression result in the echo area | |
411 | (@code{edebug-previous-result}). | |
412 | ||
413 | @item d | |
414 | Display a backtrace, excluding Edebug's own functions for clarity | |
415 | (@code{edebug-backtrace}). | |
416 | ||
417 | You cannot use debugger commands in the backtrace buffer in Edebug as | |
418 | you would in the standard debugger. | |
419 | ||
420 | The backtrace buffer is killed automatically when you continue | |
421 | execution. | |
422 | @end table | |
423 | ||
8241495d RS |
424 | You can invoke commands from Edebug that activate Edebug again |
425 | recursively. Whenever Edebug is active, you can quit to the top level | |
426 | with @kbd{q} or abort one recursive edit level with @kbd{C-]}. You can | |
427 | display a backtrace of all the pending evaluations with @kbd{d}. | |
73804d4b | 428 | |
c5f8bf2d LT |
429 | @node Breaks |
430 | @subsection Breaks | |
73804d4b | 431 | |
8241495d | 432 | Edebug's step mode stops execution when the next stop point is reached. |
73804d4b RS |
433 | There are three other ways to stop Edebug execution once it has started: |
434 | breakpoints, the global break condition, and source breakpoints. | |
435 | ||
c5f8bf2d LT |
436 | @menu |
437 | * Breakpoints:: Breakpoints at stop points. | |
d24880de GM |
438 | * Global Break Condition:: Breaking on an event. |
439 | * Source Breakpoints:: Embedding breakpoints in source code. | |
c5f8bf2d LT |
440 | @end menu |
441 | ||
442 | @node Breakpoints | |
77bf576c | 443 | @subsubsection Edebug Breakpoints |
c5f8bf2d | 444 | |
77bf576c | 445 | @cindex breakpoints (Edebug) |
73804d4b | 446 | While using Edebug, you can specify @dfn{breakpoints} in the program you |
8241495d | 447 | are testing: these are places where execution should stop. You can set a |
73804d4b RS |
448 | breakpoint at any stop point, as defined in @ref{Using Edebug}. For |
449 | setting and unsetting breakpoints, the stop point that is affected is | |
450 | the first one at or after point in the source code buffer. Here are the | |
451 | Edebug commands for breakpoints: | |
452 | ||
453 | @table @kbd | |
454 | @item b | |
455 | Set a breakpoint at the stop point at or after point | |
456 | (@code{edebug-set-breakpoint}). If you use a prefix argument, the | |
8241495d RS |
457 | breakpoint is temporary---it turns off the first time it stops the |
458 | program. | |
73804d4b RS |
459 | |
460 | @item u | |
177c0ea7 | 461 | Unset the breakpoint (if any) at the stop point at or after |
73804d4b RS |
462 | point (@code{edebug-unset-breakpoint}). |
463 | ||
464 | @item x @var{condition} @key{RET} | |
465 | Set a conditional breakpoint which stops the program only if | |
342fd6cd RS |
466 | evaluating @var{condition} produces a non-@code{nil} value |
467 | (@code{edebug-set-conditional-breakpoint}). With a prefix argument, | |
468 | the breakpoint is temporary. | |
73804d4b RS |
469 | |
470 | @item B | |
9e2b495b | 471 | Move point to the next breakpoint in the current definition |
73804d4b RS |
472 | (@code{edebug-next-breakpoint}). |
473 | @end table | |
474 | ||
475 | While in Edebug, you can set a breakpoint with @kbd{b} and unset one | |
476 | with @kbd{u}. First move point to the Edebug stop point of your choice, | |
477 | then type @kbd{b} or @kbd{u} to set or unset a breakpoint there. | |
478 | Unsetting a breakpoint where none has been set has no effect. | |
479 | ||
8241495d RS |
480 | Re-evaluating or reinstrumenting a definition removes all of its |
481 | previous breakpoints. | |
73804d4b RS |
482 | |
483 | A @dfn{conditional breakpoint} tests a condition each time the program | |
484 | gets there. Any errors that occur as a result of evaluating the | |
485 | condition are ignored, as if the result were @code{nil}. To set a | |
486 | conditional breakpoint, use @kbd{x}, and specify the condition | |
487 | expression in the minibuffer. Setting a conditional breakpoint at a | |
488 | stop point that has a previously established conditional breakpoint puts | |
489 | the previous condition expression in the minibuffer so you can edit it. | |
490 | ||
491 | You can make a conditional or unconditional breakpoint | |
969fe9b5 | 492 | @dfn{temporary} by using a prefix argument with the command to set the |
73804d4b RS |
493 | breakpoint. When a temporary breakpoint stops the program, it is |
494 | automatically unset. | |
495 | ||
8241495d | 496 | Edebug always stops or pauses at a breakpoint, except when the Edebug |
73804d4b RS |
497 | mode is Go-nonstop. In that mode, it ignores breakpoints entirely. |
498 | ||
499 | To find out where your breakpoints are, use the @kbd{B} command, which | |
87b2d5ff RS |
500 | moves point to the next breakpoint following point, within the same |
501 | function, or to the first breakpoint if there are no following | |
502 | breakpoints. This command does not continue execution---it just moves | |
503 | point in the buffer. | |
73804d4b | 504 | |
73804d4b RS |
505 | @node Global Break Condition |
506 | @subsubsection Global Break Condition | |
507 | ||
508 | @cindex stopping on events | |
509 | @cindex global break condition | |
510 | A @dfn{global break condition} stops execution when a specified | |
511 | condition is satisfied, no matter where that may occur. Edebug | |
8241495d | 512 | evaluates the global break condition at every stop point; if it |
73804d4b RS |
513 | evaluates to a non-@code{nil} value, then execution stops or pauses |
514 | depending on the execution mode, as if a breakpoint had been hit. If | |
515 | evaluating the condition gets an error, execution does not stop. | |
516 | ||
517 | @findex edebug-set-global-break-condition | |
9e2b495b RS |
518 | The condition expression is stored in |
519 | @code{edebug-global-break-condition}. You can specify a new expression | |
c5f8bf2d LT |
520 | using the @kbd{X} command from the source code buffer while Edebug is |
521 | active, or using @kbd{C-x X X} from any buffer at any time, as long as | |
522 | Edebug is loaded (@code{edebug-set-global-break-condition}). | |
73804d4b RS |
523 | |
524 | The global break condition is the simplest way to find where in your | |
525 | code some event occurs, but it makes code run much more slowly. So you | |
526 | should reset the condition to @code{nil} when not using it. | |
527 | ||
528 | @node Source Breakpoints | |
529 | @subsubsection Source Breakpoints | |
530 | ||
531 | @findex edebug | |
532 | @cindex source breakpoints | |
533 | All breakpoints in a definition are forgotten each time you | |
8241495d RS |
534 | reinstrument it. If you wish to make a breakpoint that won't be |
535 | forgotten, you can write a @dfn{source breakpoint}, which is simply a | |
536 | call to the function @code{edebug} in your source code. You can, of | |
537 | course, make such a call conditional. For example, in the @code{fac} | |
538 | function, you can insert the first line as shown below, to stop when the | |
539 | argument reaches zero: | |
73804d4b RS |
540 | |
541 | @example | |
542 | (defun fac (n) | |
543 | (if (= n 0) (edebug)) | |
544 | (if (< 0 n) | |
545 | (* n (fac (1- n))) | |
546 | 1)) | |
547 | @end example | |
548 | ||
969fe9b5 | 549 | When the @code{fac} definition is instrumented and the function is |
73804d4b RS |
550 | called, the call to @code{edebug} acts as a breakpoint. Depending on |
551 | the execution mode, Edebug stops or pauses there. | |
552 | ||
969fe9b5 | 553 | If no instrumented code is being executed when @code{edebug} is called, |
73804d4b RS |
554 | that function calls @code{debug}. |
555 | @c This may not be a good idea anymore. | |
556 | ||
557 | @node Trapping Errors | |
558 | @subsection Trapping Errors | |
559 | ||
969fe9b5 RS |
560 | Emacs normally displays an error message when an error is signaled and |
561 | not handled with @code{condition-case}. While Edebug is active and | |
562 | executing instrumented code, it normally responds to all unhandled | |
563 | errors. You can customize this with the options @code{edebug-on-error} | |
564 | and @code{edebug-on-quit}; see @ref{Edebug Options}. | |
73804d4b | 565 | |
969fe9b5 | 566 | When Edebug responds to an error, it shows the last stop point |
73804d4b | 567 | encountered before the error. This may be the location of a call to a |
8241495d | 568 | function which was not instrumented, and within which the error actually |
73804d4b RS |
569 | occurred. For an unbound variable error, the last known stop point |
570 | might be quite distant from the offending variable reference. In that | |
8241495d | 571 | case, you might want to display a full backtrace (@pxref{Edebug Misc}). |
73804d4b | 572 | |
87b2d5ff | 573 | @c Edebug should be changed for the following: -- dan |
969fe9b5 | 574 | If you change @code{debug-on-error} or @code{debug-on-quit} while |
73804d4b RS |
575 | Edebug is active, these changes will be forgotten when Edebug becomes |
576 | inactive. Furthermore, during Edebug's recursive edit, these variables | |
577 | are bound to the values they had outside of Edebug. | |
578 | ||
73804d4b RS |
579 | @node Edebug Views |
580 | @subsection Edebug Views | |
581 | ||
969fe9b5 | 582 | These Edebug commands let you view aspects of the buffer and window |
a9f0a989 | 583 | status as they were before entry to Edebug. The outside window |
87b2d5ff RS |
584 | configuration is the collection of windows and contents that were in |
585 | effect outside of Edebug. | |
73804d4b RS |
586 | |
587 | @table @kbd | |
588 | @item v | |
342fd6cd RS |
589 | Switch to viewing the outside window configuration |
590 | (@code{edebug-view-outside}). Type @kbd{C-x X w} to return to Edebug. | |
73804d4b RS |
591 | |
592 | @item p | |
c5f8bf2d LT |
593 | Temporarily display the outside current buffer with point at its |
594 | outside position (@code{edebug-bounce-point}), pausing for one second | |
595 | before returning to Edebug. With a prefix argument @var{n}, pause for | |
596 | @var{n} seconds instead. | |
73804d4b RS |
597 | |
598 | @item w | |
1911e6e5 RS |
599 | Move point back to the current stop point in the source code buffer |
600 | (@code{edebug-where}). | |
601 | ||
602 | If you use this command in a different window displaying the same | |
603 | buffer, that window will be used instead to display the current | |
604 | definition in the future. | |
73804d4b RS |
605 | |
606 | @item W | |
87b2d5ff RS |
607 | @c Its function is not simply to forget the saved configuration -- dan |
608 | Toggle whether Edebug saves and restores the outside window | |
609 | configuration (@code{edebug-toggle-save-windows}). | |
610 | ||
611 | With a prefix argument, @code{W} only toggles saving and restoring of | |
612 | the selected window. To specify a window that is not displaying the | |
613 | source code buffer, you must use @kbd{C-x X W} from the global keymap. | |
73804d4b RS |
614 | @end table |
615 | ||
969fe9b5 | 616 | You can view the outside window configuration with @kbd{v} or just |
73804d4b | 617 | bounce to the point in the current buffer with @kbd{p}, even if |
c5f8bf2d LT |
618 | it is not normally displayed. |
619 | ||
620 | After moving point, you may wish to jump back to the stop point. | |
621 | You can do that with @kbd{w} from a source code buffer. You can jump | |
622 | back to the stop point in the source code buffer from any buffer using | |
623 | @kbd{C-x X w}. | |
73804d4b | 624 | |
969fe9b5 | 625 | Each time you use @kbd{W} to turn saving @emph{off}, Edebug forgets the |
87b2d5ff RS |
626 | saved outside window configuration---so that even if you turn saving |
627 | back @emph{on}, the current window configuration remains unchanged when | |
628 | you next exit Edebug (by continuing the program). However, the | |
2bb0eca1 | 629 | automatic redisplay of @file{*edebug*} and @file{*edebug-trace*} may |
87b2d5ff RS |
630 | conflict with the buffers you wish to see unless you have enough windows |
631 | open. | |
73804d4b RS |
632 | |
633 | @node Edebug Eval | |
634 | @subsection Evaluation | |
635 | ||
650b6d0b | 636 | While within Edebug, you can evaluate expressions as if Edebug |
8241495d | 637 | were not running. Edebug tries to be invisible to the expression's |
73804d4b | 638 | evaluation and printing. Evaluation of expressions that cause side |
8241495d RS |
639 | effects will work as expected, except for changes to data that Edebug |
640 | explicitly saves and restores. @xref{The Outside Context}, for details | |
641 | on this process. | |
73804d4b RS |
642 | |
643 | @table @kbd | |
644 | @item e @var{exp} @key{RET} | |
645 | Evaluate expression @var{exp} in the context outside of Edebug | |
646 | (@code{edebug-eval-expression}). That is, Edebug tries to minimize its | |
647 | interference with the evaluation. | |
648 | ||
bfe721d1 | 649 | @item M-: @var{exp} @key{RET} |
622fa380 GM |
650 | Evaluate expression @var{exp} in the context of Edebug itself |
651 | (@code{eval-expression}). | |
73804d4b RS |
652 | |
653 | @item C-x C-e | |
654 | Evaluate the expression before point, in the context outside of Edebug | |
655 | (@code{edebug-eval-last-sexp}). | |
656 | @end table | |
657 | ||
658 | @cindex lexical binding (Edebug) | |
969fe9b5 | 659 | Edebug supports evaluation of expressions containing references to |
73804d4b | 660 | lexically bound symbols created by the following constructs in |
622fa380 GM |
661 | @file{cl.el}: @code{lexical-let}, @code{macrolet}, and |
662 | @code{symbol-macrolet}. | |
650b6d0b | 663 | @c FIXME? What about lexical-binding = t? |
73804d4b | 664 | |
73804d4b RS |
665 | @node Eval List |
666 | @subsection Evaluation List Buffer | |
667 | ||
2bb0eca1 | 668 | You can use the @dfn{evaluation list buffer}, called @file{*edebug*}, to |
73804d4b RS |
669 | evaluate expressions interactively. You can also set up the |
670 | @dfn{evaluation list} of expressions to be evaluated automatically each | |
671 | time Edebug updates the display. | |
672 | ||
673 | @table @kbd | |
674 | @item E | |
2bb0eca1 | 675 | Switch to the evaluation list buffer @file{*edebug*} |
73804d4b RS |
676 | (@code{edebug-visit-eval-list}). |
677 | @end table | |
678 | ||
2bb0eca1 | 679 | In the @file{*edebug*} buffer you can use the commands of Lisp |
73804d4b RS |
680 | Interaction mode (@pxref{Lisp Interaction,,, emacs, The GNU Emacs |
681 | Manual}) as well as these special commands: | |
682 | ||
683 | @table @kbd | |
969fe9b5 | 684 | @item C-j |
73804d4b RS |
685 | Evaluate the expression before point, in the outside context, and insert |
686 | the value in the buffer (@code{edebug-eval-print-last-sexp}). | |
687 | ||
688 | @item C-x C-e | |
689 | Evaluate the expression before point, in the context outside of Edebug | |
690 | (@code{edebug-eval-last-sexp}). | |
691 | ||
692 | @item C-c C-u | |
87b2d5ff | 693 | Build a new evaluation list from the contents of the buffer |
73804d4b RS |
694 | (@code{edebug-update-eval-list}). |
695 | ||
696 | @item C-c C-d | |
697 | Delete the evaluation list group that point is in | |
698 | (@code{edebug-delete-eval-item}). | |
699 | ||
700 | @item C-c C-w | |
701 | Switch back to the source code buffer at the current stop point | |
702 | (@code{edebug-where}). | |
703 | @end table | |
704 | ||
969fe9b5 | 705 | You can evaluate expressions in the evaluation list window with |
2bb0eca1 | 706 | @kbd{C-j} or @kbd{C-x C-e}, just as you would in @file{*scratch*}; |
73804d4b RS |
707 | but they are evaluated in the context outside of Edebug. |
708 | ||
969fe9b5 | 709 | The expressions you enter interactively (and their results) are lost |
73804d4b | 710 | when you continue execution; but you can set up an @dfn{evaluation list} |
177c0ea7 | 711 | consisting of expressions to be evaluated each time execution stops. |
73804d4b RS |
712 | |
713 | @cindex evaluation list group | |
969fe9b5 | 714 | To do this, write one or more @dfn{evaluation list groups} in the |
73804d4b RS |
715 | evaluation list buffer. An evaluation list group consists of one or |
716 | more Lisp expressions. Groups are separated by comment lines. | |
717 | ||
969fe9b5 | 718 | The command @kbd{C-c C-u} (@code{edebug-update-eval-list}) rebuilds the |
73804d4b | 719 | evaluation list, scanning the buffer and using the first expression of |
87b2d5ff RS |
720 | each group. (The idea is that the second expression of the group is the |
721 | value previously computed and displayed.) | |
73804d4b | 722 | |
969fe9b5 | 723 | Each entry to Edebug redisplays the evaluation list by inserting each |
87b2d5ff RS |
724 | expression in the buffer, followed by its current value. It also |
725 | inserts comment lines so that each expression becomes its own group. | |
726 | Thus, if you type @kbd{C-c C-u} again without changing the buffer text, | |
727 | the evaluation list is effectively unchanged. | |
73804d4b | 728 | |
622fa380 GM |
729 | If an error occurs during an evaluation from the evaluation list, |
730 | the error message is displayed in a string as if it were the result. | |
731 | Therefore, expressions using variables that are not currently valid do | |
732 | not interrupt your debugging. | |
73804d4b | 733 | |
969fe9b5 | 734 | Here is an example of what the evaluation list window looks like after |
73804d4b RS |
735 | several expressions have been added to it: |
736 | ||
737 | @smallexample | |
738 | (current-buffer) | |
739 | #<buffer *scratch*> | |
740 | ;--------------------------------------------------------------- | |
741 | (selected-window) | |
742 | #<window 16 on *scratch*> | |
743 | ;--------------------------------------------------------------- | |
744 | (point) | |
745 | 196 | |
746 | ;--------------------------------------------------------------- | |
747 | bad-var | |
748 | "Symbol's value as variable is void: bad-var" | |
749 | ;--------------------------------------------------------------- | |
750 | (recursion-depth) | |
751 | 0 | |
752 | ;--------------------------------------------------------------- | |
753 | this-command | |
754 | eval-last-sexp | |
755 | ;--------------------------------------------------------------- | |
756 | @end smallexample | |
757 | ||
758 | To delete a group, move point into it and type @kbd{C-c C-d}, or simply | |
759 | delete the text for the group and update the evaluation list with | |
760 | @kbd{C-c C-u}. To add a new expression to the evaluation list, insert | |
8241495d RS |
761 | the expression at a suitable place, insert a new comment line, then type |
762 | @kbd{C-c C-u}. You need not insert dashes in the comment line---its | |
763 | contents don't matter. | |
73804d4b | 764 | |
2bb0eca1 GM |
765 | After selecting @file{*edebug*}, you can return to the source code |
766 | buffer with @kbd{C-c C-w}. The @file{*edebug*} buffer is killed when | |
73804d4b RS |
767 | you continue execution, and recreated next time it is needed. |
768 | ||
73804d4b RS |
769 | @node Printing in Edebug |
770 | @subsection Printing in Edebug | |
771 | ||
772 | @cindex printing (Edebug) | |
773 | @cindex printing circular structures | |
774 | @pindex cust-print | |
775 | If an expression in your program produces a value containing circular | |
776 | list structure, you may get an error when Edebug attempts to print it. | |
777 | ||
73804d4b RS |
778 | One way to cope with circular structure is to set @code{print-length} |
779 | or @code{print-level} to truncate the printing. Edebug does this for | |
622fa380 GM |
780 | you; it binds @code{print-length} and @code{print-level} to the values |
781 | of the variables @code{edebug-print-length} and | |
782 | @code{edebug-print-level} (so long as they have non-@code{nil} | |
783 | values). @xref{Output Variables}. | |
73804d4b | 784 | |
969fe9b5 | 785 | @defopt edebug-print-length |
8241495d RS |
786 | If non-@code{nil}, Edebug binds @code{print-length} to this value while |
787 | printing results. The default value is @code{50}. | |
969fe9b5 RS |
788 | @end defopt |
789 | ||
177c0ea7 | 790 | @defopt edebug-print-level |
8241495d RS |
791 | If non-@code{nil}, Edebug binds @code{print-level} to this value while |
792 | printing results. The default value is @code{50}. | |
969fe9b5 RS |
793 | @end defopt |
794 | ||
73804d4b | 795 | You can also print circular structures and structures that share |
8241495d RS |
796 | elements more informatively by binding @code{print-circle} |
797 | to a non-@code{nil} value. | |
73804d4b RS |
798 | |
799 | Here is an example of code that creates a circular structure: | |
800 | ||
801 | @example | |
802 | (setq a '(x y)) | |
a9f0a989 | 803 | (setcar a a) |
73804d4b RS |
804 | @end example |
805 | ||
806 | @noindent | |
807 | Custom printing prints this as @samp{Result: #1=(#1# y)}. The | |
808 | @samp{#1=} notation labels the structure that follows it with the label | |
a9f0a989 | 809 | @samp{1}, and the @samp{#1#} notation references the previously labeled |
73804d4b RS |
810 | structure. This notation is used for any shared elements of lists or |
811 | vectors. | |
812 | ||
177c0ea7 | 813 | @defopt edebug-print-circle |
8241495d | 814 | If non-@code{nil}, Edebug binds @code{print-circle} to this value while |
011caae1 | 815 | printing results. The default value is @code{t}. |
969fe9b5 RS |
816 | @end defopt |
817 | ||
73804d4b RS |
818 | Other programs can also use custom printing; see @file{cust-print.el} |
819 | for details. | |
820 | ||
821 | @node Trace Buffer | |
822 | @subsection Trace Buffer | |
823 | @cindex trace buffer | |
824 | ||
87b2d5ff | 825 | Edebug can record an execution trace, storing it in a buffer named |
2bb0eca1 | 826 | @file{*edebug-trace*}. This is a log of function calls and returns, |
73804d4b RS |
827 | showing the function names and their arguments and values. To enable |
828 | trace recording, set @code{edebug-trace} to a non-@code{nil} value. | |
829 | ||
830 | Making a trace buffer is not the same thing as using trace execution | |
831 | mode (@pxref{Edebug Execution Modes}). | |
832 | ||
833 | When trace recording is enabled, each function entry and exit adds | |
8241495d RS |
834 | lines to the trace buffer. A function entry record consists of |
835 | @samp{::::@{}, followed by the function name and argument values. A | |
836 | function exit record consists of @samp{::::@}}, followed by the function | |
73804d4b RS |
837 | name and result of the function. |
838 | ||
839 | The number of @samp{:}s in an entry shows its recursion depth. You | |
840 | can use the braces in the trace buffer to find the matching beginning or | |
841 | end of function calls. | |
842 | ||
843 | @findex edebug-print-trace-before | |
844 | @findex edebug-print-trace-after | |
845 | You can customize trace recording for function entry and exit by | |
846 | redefining the functions @code{edebug-print-trace-before} and | |
847 | @code{edebug-print-trace-after}. | |
848 | ||
849 | @defmac edebug-tracing string body@dots{} | |
850 | This macro requests additional trace information around the execution | |
851 | of the @var{body} forms. The argument @var{string} specifies text | |
c5f8bf2d LT |
852 | to put in the trace buffer, after the @samp{@{} or @samp{@}}. All |
853 | the arguments are evaluated, and @code{edebug-tracing} returns the | |
854 | value of the last form in @var{body}. | |
73804d4b RS |
855 | @end defmac |
856 | ||
857 | @defun edebug-trace format-string &rest format-args | |
858 | This function inserts text in the trace buffer. It computes the text | |
859 | with @code{(apply 'format @var{format-string} @var{format-args})}. | |
87b2d5ff | 860 | It also appends a newline to separate entries. |
73804d4b RS |
861 | @end defun |
862 | ||
1911e6e5 RS |
863 | @code{edebug-tracing} and @code{edebug-trace} insert lines in the |
864 | trace buffer whenever they are called, even if Edebug is not active. | |
865 | Adding text to the trace buffer also scrolls its window to show the last | |
866 | lines inserted. | |
73804d4b | 867 | |
73804d4b RS |
868 | @node Coverage Testing |
869 | @subsection Coverage Testing | |
870 | ||
77bf576c | 871 | @cindex coverage testing (Edebug) |
73804d4b RS |
872 | @cindex frequency counts |
873 | @cindex performance analysis | |
77bf576c | 874 | Edebug provides rudimentary coverage testing and display of execution |
1911e6e5 RS |
875 | frequency. |
876 | ||
877 | Coverage testing works by comparing the result of each expression with | |
878 | the previous result; each form in the program is considered ``covered'' | |
879 | if it has returned two different values since you began testing coverage | |
880 | in the current Emacs session. Thus, to do coverage testing on your | |
881 | program, execute it under various conditions and note whether it behaves | |
882 | correctly; Edebug will tell you when you have tried enough different | |
883 | conditions that each form has returned two different values. | |
884 | ||
885 | Coverage testing makes execution slower, so it is only done if | |
ebc6903b | 886 | @code{edebug-test-coverage} is non-@code{nil}. Frequency counting is |
622fa380 | 887 | performed for all executions of an instrumented function, even if the |
ebc6903b RS |
888 | execution mode is Go-nonstop, and regardless of whether coverage testing |
889 | is enabled. | |
1911e6e5 | 890 | |
89f6de49 RS |
891 | @kindex C-x X = |
892 | @findex edebug-temp-display-freq-count | |
893 | Use @kbd{C-x X =} (@code{edebug-display-freq-count}) to display both | |
894 | the coverage information and the frequency counts for a definition. | |
895 | Just @kbd{=} (@code{edebug-temp-display-freq-count}) displays the same | |
896 | information temporarily, only until you type another key. | |
73804d4b RS |
897 | |
898 | @deffn Command edebug-display-freq-count | |
899 | This command displays the frequency count data for each line of the | |
900 | current definition. | |
901 | ||
622fa380 GM |
902 | It inserts frequency counts as comment lines after each line of code. |
903 | You can undo all insertions with one @code{undo} command. The counts | |
904 | appear under the @samp{(} before an expression or the @samp{)} after | |
905 | an expression, or on the last character of a variable. To simplify | |
906 | the display, a count is not shown if it is equal to the count of an | |
907 | earlier expression on the same line. | |
73804d4b RS |
908 | |
909 | The character @samp{=} following the count for an expression says that | |
a9f0a989 | 910 | the expression has returned the same value each time it was evaluated. |
1911e6e5 | 911 | In other words, it is not yet ``covered'' for coverage testing purposes. |
73804d4b RS |
912 | |
913 | To clear the frequency count and coverage data for a definition, | |
a9f0a989 | 914 | simply reinstrument it with @code{eval-defun}. |
73804d4b RS |
915 | @end deffn |
916 | ||
917 | For example, after evaluating @code{(fac 5)} with a source | |
918 | breakpoint, and setting @code{edebug-test-coverage} to @code{t}, when | |
919 | the breakpoint is reached, the frequency data looks like this: | |
920 | ||
921 | @example | |
922 | (defun fac (n) | |
923 | (if (= n 0) (edebug)) | |
011caae1 | 924 | ;#6 1 = =5 |
73804d4b | 925 | (if (< 0 n) |
177c0ea7 | 926 | ;#5 = |
73804d4b | 927 | (* n (fac (1- n))) |
177c0ea7 | 928 | ;# 5 0 |
73804d4b | 929 | 1)) |
177c0ea7 | 930 | ;# 0 |
73804d4b RS |
931 | @end example |
932 | ||
87b2d5ff RS |
933 | The comment lines show that @code{fac} was called 6 times. The |
934 | first @code{if} statement returned 5 times with the same result each | |
73804d4b | 935 | time; the same is true of the condition on the second @code{if}. |
87b2d5ff | 936 | The recursive call of @code{fac} did not return at all. |
73804d4b RS |
937 | |
938 | ||
939 | @node The Outside Context | |
940 | @subsection The Outside Context | |
941 | ||
942 | Edebug tries to be transparent to the program you are debugging, but it | |
943 | does not succeed completely. Edebug also tries to be transparent when | |
944 | you evaluate expressions with @kbd{e} or with the evaluation list | |
945 | buffer, by temporarily restoring the outside context. This section | |
946 | explains precisely what context Edebug restores, and how Edebug fails to | |
947 | be completely transparent. | |
948 | ||
73804d4b | 949 | @menu |
d24880de GM |
950 | * Checking Whether to Stop:: When Edebug decides what to do. |
951 | * Edebug Display Update:: When Edebug updates the display. | |
952 | * Edebug Recursive Edit:: When Edebug stops execution. | |
73804d4b RS |
953 | @end menu |
954 | ||
955 | @node Checking Whether to Stop | |
956 | @subsubsection Checking Whether to Stop | |
957 | ||
87b2d5ff RS |
958 | Whenever Edebug is entered, it needs to save and restore certain data |
959 | before even deciding whether to make trace information or stop the | |
960 | program. | |
73804d4b RS |
961 | |
962 | @itemize @bullet | |
177c0ea7 | 963 | @item |
73804d4b | 964 | @code{max-lisp-eval-depth} and @code{max-specpdl-size} are both |
622fa380 GM |
965 | increased to reduce Edebug's impact on the stack. You could, however, |
966 | still run out of stack space when using Edebug. | |
73804d4b | 967 | |
177c0ea7 | 968 | @item |
73804d4b | 969 | The state of keyboard macro execution is saved and restored. While |
473671bd RS |
970 | Edebug is active, @code{executing-kbd-macro} is bound to @code{nil} |
971 | unless @code{edebug-continue-kbd-macro} is non-@code{nil}. | |
73804d4b RS |
972 | @end itemize |
973 | ||
974 | ||
975 | @node Edebug Display Update | |
976 | @subsubsection Edebug Display Update | |
977 | ||
87b2d5ff RS |
978 | @c This paragraph is not filled, because LaLiberte's conversion script |
979 | @c needs an xref to be on just one line. | |
73804d4b | 980 | When Edebug needs to display something (e.g., in trace mode), it saves |
177c0ea7 | 981 | the current window configuration from ``outside'' Edebug |
161c2a25 GM |
982 | (@pxref{Window Configurations}). When you exit Edebug, it restores |
983 | the previous window configuration. | |
73804d4b RS |
984 | |
985 | Emacs redisplays only when it pauses. Usually, when you continue | |
8241495d RS |
986 | execution, the program re-enters Edebug at a breakpoint or after |
987 | stepping, without pausing or reading input in between. In such cases, | |
73804d4b | 988 | Emacs never gets a chance to redisplay the ``outside'' configuration. |
8241495d RS |
989 | Consequently, what you see is the same window configuration as the last |
990 | time Edebug was active, with no interruption. | |
73804d4b RS |
991 | |
992 | Entry to Edebug for displaying something also saves and restores the | |
8241495d RS |
993 | following data (though some of them are deliberately not restored if an |
994 | error or quit signal occurs). | |
73804d4b RS |
995 | |
996 | @itemize @bullet | |
177c0ea7 | 997 | @item |
73804d4b RS |
998 | @cindex current buffer point and mark (Edebug) |
999 | Which buffer is current, and the positions of point and the mark in the | |
1000 | current buffer, are saved and restored. | |
1001 | ||
177c0ea7 | 1002 | @item |
73804d4b RS |
1003 | @cindex window configuration (Edebug) |
1004 | The outside window configuration is saved and restored if | |
c5f8bf2d | 1005 | @code{edebug-save-windows} is non-@code{nil} (@pxref{Edebug Options}). |
73804d4b RS |
1006 | |
1007 | The window configuration is not restored on error or quit, but the | |
1008 | outside selected window @emph{is} reselected even on error or quit in | |
1009 | case a @code{save-excursion} is active. If the value of | |
1010 | @code{edebug-save-windows} is a list, only the listed windows are saved | |
1011 | and restored. | |
1012 | ||
1013 | The window start and horizontal scrolling of the source code buffer are | |
1014 | not restored, however, so that the display remains coherent within Edebug. | |
1015 | ||
1016 | @item | |
73804d4b RS |
1017 | The value of point in each displayed buffer is saved and restored if |
1018 | @code{edebug-save-displayed-buffer-points} is non-@code{nil}. | |
1019 | ||
1020 | @item | |
1021 | The variables @code{overlay-arrow-position} and | |
622fa380 | 1022 | @code{overlay-arrow-string} are saved and restored, so you can safely |
73804d4b RS |
1023 | invoke Edebug from the recursive edit elsewhere in the same buffer. |
1024 | ||
177c0ea7 | 1025 | @item |
73804d4b RS |
1026 | @code{cursor-in-echo-area} is locally bound to @code{nil} so that |
1027 | the cursor shows up in the window. | |
1028 | @end itemize | |
1029 | ||
1030 | @node Edebug Recursive Edit | |
1031 | @subsubsection Edebug Recursive Edit | |
1032 | ||
1033 | When Edebug is entered and actually reads commands from the user, it | |
1034 | saves (and later restores) these additional data: | |
1035 | ||
1036 | @itemize @bullet | |
1037 | @item | |
1038 | The current match data. @xref{Match Data}. | |
1039 | ||
1040 | @item | |
342fd6cd | 1041 | The variables @code{last-command}, @code{this-command}, |
84f4a531 | 1042 | @code{last-command-event}, @code{last-input-event}, |
342fd6cd | 1043 | @code{last-event-frame}, @code{last-nonmenu-event}, and |
84f4a531 CY |
1044 | @code{track-mouse}. Commands in Edebug do not affect these variables |
1045 | outside of Edebug. | |
73804d4b | 1046 | |
94da4eb4 RS |
1047 | Executing commands within Edebug can change the key sequence that |
1048 | would be returned by @code{this-command-keys}, and there is no way to | |
1049 | reset the key sequence from Lisp. | |
73804d4b | 1050 | |
87b2d5ff RS |
1051 | Edebug cannot save and restore the value of |
1052 | @code{unread-command-events}. Entering Edebug while this variable has a | |
1053 | nontrivial value can interfere with execution of the program you are | |
1054 | debugging. | |
1055 | ||
73804d4b RS |
1056 | @item |
1057 | Complex commands executed while in Edebug are added to the variable | |
1058 | @code{command-history}. In rare cases this can alter execution. | |
1059 | ||
1060 | @item | |
1061 | Within Edebug, the recursion depth appears one deeper than the recursion | |
1062 | depth outside Edebug. This is not true of the automatically updated | |
1063 | evaluation list window. | |
1064 | ||
1065 | @item | |
1066 | @code{standard-output} and @code{standard-input} are bound to @code{nil} | |
1067 | by the @code{recursive-edit}, but Edebug temporarily restores them during | |
1068 | evaluations. | |
1069 | ||
177c0ea7 | 1070 | @item |
73804d4b RS |
1071 | The state of keyboard macro definition is saved and restored. While |
1072 | Edebug is active, @code{defining-kbd-macro} is bound to | |
1073 | @code{edebug-continue-kbd-macro}. | |
1074 | @end itemize | |
1075 | ||
c5f8bf2d LT |
1076 | @node Edebug and Macros |
1077 | @subsection Edebug and Macros | |
1078 | ||
1079 | To make Edebug properly instrument expressions that call macros, some | |
1080 | extra care is needed. This subsection explains the details. | |
1081 | ||
1082 | @menu | |
1083 | * Instrumenting Macro Calls:: The basic problem. | |
d24880de GM |
1084 | * Specification List:: How to specify complex patterns of evaluation. |
1085 | * Backtracking:: What Edebug does when matching fails. | |
1086 | * Specification Examples:: To help understand specifications. | |
c5f8bf2d LT |
1087 | @end menu |
1088 | ||
73804d4b | 1089 | @node Instrumenting Macro Calls |
c5f8bf2d | 1090 | @subsubsection Instrumenting Macro Calls |
73804d4b | 1091 | |
969fe9b5 RS |
1092 | When Edebug instruments an expression that calls a Lisp macro, it needs |
1093 | additional information about the macro to do the job properly. This is | |
1094 | because there is no a-priori way to tell which subexpressions of the | |
1095 | macro call are forms to be evaluated. (Evaluation may occur explicitly | |
1096 | in the macro body, or when the resulting expansion is evaluated, or any | |
1097 | time later.) | |
1098 | ||
f9350c5c RS |
1099 | Therefore, you must define an Edebug specification for each macro |
1100 | that Edebug will encounter, to explain the format of calls to that | |
a7679889 | 1101 | macro. To do this, add a @code{debug} declaration to the macro |
f9350c5c RS |
1102 | definition. Here is a simple example that shows the specification for |
1103 | the @code{for} example macro (@pxref{Argument Evaluation}). | |
1104 | ||
342fd6cd | 1105 | @smallexample |
f9350c5c RS |
1106 | (defmacro for (var from init to final do &rest body) |
1107 | "Execute a simple \"for\" loop. | |
1108 | For example, (for i from 1 to 10 do (print i))." | |
af5a6df7 | 1109 | (declare (debug (symbolp "from" form "to" form "do" &rest form))) |
f9350c5c | 1110 | ...) |
342fd6cd | 1111 | @end smallexample |
f9350c5c | 1112 | |
89f6de49 | 1113 | The Edebug specification says which parts of a call to the macro are |
622fa380 | 1114 | forms to be evaluated. For simple macros, the specification |
a756468d RS |
1115 | often looks very similar to the formal argument list of the macro |
1116 | definition, but specifications are much more general than macro | |
1117 | arguments. @xref{Defining Macros}, for more explanation of | |
40d2bb40 | 1118 | the @code{declare} form. |
a756468d | 1119 | |
1df7defd | 1120 | @c See, e.g., http://debbugs.gnu.org/10577 |
0b021094 GM |
1121 | @c FIXME Maybe there should be an Edebug option to get it to |
1122 | @c automatically load the entire source file containing the function | |
1123 | @c being instrumented. That would avoid this. | |
1124 | Take care to ensure that the specifications are known to Edebug when | |
1125 | you instrument code. If you are instrumenting a function from a file | |
1126 | that uses @code{eval-when-compile} to require another file containing | |
1127 | macro definitions, you may need to explicitly load that file. | |
1128 | ||
a756468d | 1129 | You can also define an edebug specification for a macro separately |
f9350c5c | 1130 | from the macro definition with @code{def-edebug-spec}. Adding |
a7679889 LK |
1131 | @code{debug} declarations is preferred, and more convenient, for macro |
1132 | definitions in Lisp, but @code{def-edebug-spec} makes it possible to | |
1133 | define Edebug specifications for special forms implemented in C. | |
73804d4b RS |
1134 | |
1135 | @deffn Macro def-edebug-spec macro specification | |
1136 | Specify which expressions of a call to macro @var{macro} are forms to be | |
f9350c5c | 1137 | evaluated. @var{specification} should be the edebug specification. |
c5f8bf2d | 1138 | Neither argument is evaluated. |
73804d4b | 1139 | |
969fe9b5 | 1140 | The @var{macro} argument can actually be any symbol, not just a macro |
73804d4b RS |
1141 | name. |
1142 | @end deffn | |
1143 | ||
73804d4b RS |
1144 | Here is a table of the possibilities for @var{specification} and how each |
1145 | directs processing of arguments. | |
1146 | ||
ec221d13 | 1147 | @table @asis |
73804d4b RS |
1148 | @item @code{t} |
1149 | All arguments are instrumented for evaluation. | |
1150 | ||
1151 | @item @code{0} | |
1152 | None of the arguments is instrumented. | |
1153 | ||
1154 | @item a symbol | |
622fa380 | 1155 | The symbol must have an Edebug specification, which is used instead. |
73804d4b | 1156 | This indirection is repeated until another kind of specification is |
a9f0a989 | 1157 | found. This allows you to inherit the specification from another macro. |
73804d4b RS |
1158 | |
1159 | @item a list | |
1160 | The elements of the list describe the types of the arguments of a | |
1161 | calling form. The possible elements of a specification list are | |
1162 | described in the following sections. | |
1163 | @end table | |
1164 | ||
c5f8bf2d LT |
1165 | If a macro has no Edebug specification, neither through a @code{debug} |
1166 | declaration nor through a @code{def-edebug-spec} call, the variable | |
622fa380 GM |
1167 | @code{edebug-eval-macro-args} comes into play. |
1168 | ||
1169 | @defopt edebug-eval-macro-args | |
1170 | This controls the way Edebug treats macro arguments with no explicit | |
1171 | Edebug specification. If it is @code{nil} (the default), none of the | |
1172 | arguments is instrumented for evaluation. Otherwise, all arguments | |
1173 | are instrumented. | |
1174 | @end defopt | |
73804d4b RS |
1175 | |
1176 | @node Specification List | |
1177 | @subsubsection Specification List | |
1178 | ||
1179 | @cindex Edebug specification list | |
1180 | A @dfn{specification list} is required for an Edebug specification if | |
1181 | some arguments of a macro call are evaluated while others are not. Some | |
1182 | elements in a specification list match one or more arguments, but others | |
1183 | modify the processing of all following elements. The latter, called | |
1184 | @dfn{specification keywords}, are symbols beginning with @samp{&} (such | |
1185 | as @code{&optional}). | |
1186 | ||
650b6d0b | 1187 | A specification list may contain sublists, which match arguments that are |
73804d4b RS |
1188 | themselves lists, or it may contain vectors used for grouping. Sublists |
1189 | and groups thus subdivide the specification list into a hierarchy of | |
969fe9b5 | 1190 | levels. Specification keywords apply only to the remainder of the |
73804d4b RS |
1191 | sublist or group they are contained in. |
1192 | ||
1193 | When a specification list involves alternatives or repetition, matching | |
622fa380 GM |
1194 | it against an actual macro call may require backtracking. For more |
1195 | details, @pxref{Backtracking}. | |
73804d4b RS |
1196 | |
1197 | Edebug specifications provide the power of regular expression matching, | |
1198 | plus some context-free grammar constructs: the matching of sublists with | |
1199 | balanced parentheses, recursive processing of forms, and recursion via | |
1200 | indirect specifications. | |
1201 | ||
1202 | Here's a table of the possible elements of a specification list, with | |
67c1390d LT |
1203 | their meanings (see @ref{Specification Examples}, for the referenced |
1204 | examples): | |
73804d4b RS |
1205 | |
1206 | @table @code | |
1207 | @item sexp | |
1911e6e5 | 1208 | A single unevaluated Lisp object, which is not instrumented. |
a9f0a989 | 1209 | @c an "expression" is not necessarily intended for evaluation. |
73804d4b RS |
1210 | |
1211 | @item form | |
1212 | A single evaluated expression, which is instrumented. | |
1213 | ||
1214 | @item place | |
7c08f8ba | 1215 | A generalized variable. @xref{Generalized Variables}. |
73804d4b RS |
1216 | |
1217 | @item body | |
1218 | Short for @code{&rest form}. See @code{&rest} below. | |
1219 | ||
1220 | @item function-form | |
1221 | A function form: either a quoted function symbol, a quoted lambda | |
1222 | expression, or a form (that should evaluate to a function symbol or | |
1223 | lambda expression). This is useful when an argument that's a lambda | |
1224 | expression might be quoted with @code{quote} rather than | |
1225 | @code{function}, since it instruments the body of the lambda expression | |
1226 | either way. | |
1227 | ||
1228 | @item lambda-expr | |
1229 | A lambda expression with no quoting. | |
1230 | ||
1231 | @item &optional | |
89f6de49 | 1232 | @c @kindex &optional @r{(Edebug)} |
73804d4b | 1233 | All following elements in the specification list are optional; as soon |
177c0ea7 | 1234 | as one does not match, Edebug stops matching at this level. |
73804d4b | 1235 | |
650b6d0b | 1236 | To make just a few elements optional, followed by non-optional elements, |
73804d4b RS |
1237 | use @code{[&optional @var{specs}@dots{}]}. To specify that several |
1238 | elements must all match or none, use @code{&optional | |
67c1390d | 1239 | [@var{specs}@dots{}]}. See the @code{defun} example. |
73804d4b RS |
1240 | |
1241 | @item &rest | |
89f6de49 | 1242 | @c @kindex &rest @r{(Edebug)} |
73804d4b | 1243 | All following elements in the specification list are repeated zero or |
ebc6903b RS |
1244 | more times. In the last repetition, however, it is not a problem if the |
1245 | expression runs out before matching all of the elements of the | |
1246 | specification list. | |
73804d4b RS |
1247 | |
1248 | To repeat only a few elements, use @code{[&rest @var{specs}@dots{}]}. | |
1249 | To specify several elements that must all match on every repetition, use | |
1250 | @code{&rest [@var{specs}@dots{}]}. | |
1251 | ||
1252 | @item &or | |
89f6de49 | 1253 | @c @kindex &or @r{(Edebug)} |
73804d4b RS |
1254 | Each of the following elements in the specification list is an |
1255 | alternative. One of the alternatives must match, or the @code{&or} | |
1256 | specification fails. | |
1257 | ||
1258 | Each list element following @code{&or} is a single alternative. To | |
1259 | group two or more list elements as a single alternative, enclose them in | |
1260 | @code{[@dots{}]}. | |
1261 | ||
1262 | @item ¬ | |
89f6de49 | 1263 | @c @kindex ¬ @r{(Edebug)} |
73804d4b RS |
1264 | Each of the following elements is matched as alternatives as if by using |
1265 | @code{&or}, but if any of them match, the specification fails. If none | |
1266 | of them match, nothing is matched, but the @code{¬} specification | |
1267 | succeeds. | |
1268 | ||
0b021094 GM |
1269 | @c FIXME &key? |
1270 | ||
177c0ea7 | 1271 | @item &define |
89f6de49 | 1272 | @c @kindex &define @r{(Edebug)} |
73804d4b | 1273 | Indicates that the specification is for a defining form. The defining |
a9f0a989 | 1274 | form itself is not instrumented (that is, Edebug does not stop before and |
73804d4b RS |
1275 | after the defining form), but forms inside it typically will be |
1276 | instrumented. The @code{&define} keyword should be the first element in | |
1277 | a list specification. | |
1278 | ||
1279 | @item nil | |
1280 | This is successful when there are no more arguments to match at the | |
1281 | current argument list level; otherwise it fails. See sublist | |
67c1390d | 1282 | specifications and the backquote example. |
73804d4b RS |
1283 | |
1284 | @item gate | |
1285 | @cindex preventing backtracking | |
1286 | No argument is matched but backtracking through the gate is disabled | |
1287 | while matching the remainder of the specifications at this level. This | |
1288 | is primarily used to generate more specific syntax error messages. See | |
67c1390d | 1289 | @ref{Backtracking}, for more details. Also see the @code{let} example. |
73804d4b RS |
1290 | |
1291 | @item @var{other-symbol} | |
1292 | @cindex indirect specifications | |
1293 | Any other symbol in a specification list may be a predicate or an | |
1294 | indirect specification. | |
1295 | ||
1296 | If the symbol has an Edebug specification, this @dfn{indirect | |
1297 | specification} should be either a list specification that is used in | |
1298 | place of the symbol, or a function that is called to process the | |
1299 | arguments. The specification may be defined with @code{def-edebug-spec} | |
622fa380 | 1300 | just as for macros. See the @code{defun} example. |
73804d4b RS |
1301 | |
1302 | Otherwise, the symbol should be a predicate. The predicate is called | |
650b6d0b GM |
1303 | with the argument, and if the predicate returns @code{nil}, the |
1304 | specification fails and the argument is not instrumented. | |
73804d4b | 1305 | |
73804d4b RS |
1306 | Some suitable predicates include @code{symbolp}, @code{integerp}, |
1307 | @code{stringp}, @code{vectorp}, and @code{atom}. | |
73804d4b RS |
1308 | |
1309 | @item [@var{elements}@dots{}] | |
1310 | @cindex [@dots{}] (Edebug) | |
1311 | A vector of elements groups the elements into a single @dfn{group | |
1312 | specification}. Its meaning has nothing to do with vectors. | |
1313 | ||
1314 | @item "@var{string}" | |
1315 | The argument should be a symbol named @var{string}. This specification | |
1316 | is equivalent to the quoted symbol, @code{'@var{symbol}}, where the name | |
1317 | of @var{symbol} is the @var{string}, but the string form is preferred. | |
1318 | ||
73804d4b RS |
1319 | @item (vector @var{elements}@dots{}) |
1320 | The argument should be a vector whose elements must match the | |
67c1390d | 1321 | @var{elements} in the specification. See the backquote example. |
73804d4b RS |
1322 | |
1323 | @item (@var{elements}@dots{}) | |
1324 | Any other list is a @dfn{sublist specification} and the argument must be | |
1325 | a list whose elements match the specification @var{elements}. | |
1326 | ||
1327 | @cindex dotted lists (Edebug) | |
1328 | A sublist specification may be a dotted list and the corresponding list | |
1329 | argument may then be a dotted list. Alternatively, the last @sc{cdr} of a | |
1330 | dotted list specification may be another sublist specification (via a | |
a9f0a989 | 1331 | grouping or an indirect specification, e.g., @code{(spec . [(more |
73804d4b RS |
1332 | specs@dots{})])}) whose elements match the non-dotted list arguments. |
1333 | This is useful in recursive specifications such as in the backquote | |
67c1390d | 1334 | example. Also see the description of a @code{nil} specification |
73804d4b RS |
1335 | above for terminating such recursion. |
1336 | ||
87b2d5ff RS |
1337 | Note that a sublist specification written as @code{(specs . nil)} |
1338 | is equivalent to @code{(specs)}, and @code{(specs . | |
1339 | (sublist-elements@dots{}))} is equivalent to @code{(specs | |
73804d4b RS |
1340 | sublist-elements@dots{})}. |
1341 | @end table | |
1342 | ||
1343 | @c Need to document extensions with &symbol and :symbol | |
1344 | ||
969fe9b5 | 1345 | Here is a list of additional specifications that may appear only after |
67c1390d | 1346 | @code{&define}. See the @code{defun} example. |
73804d4b RS |
1347 | |
1348 | @table @code | |
1349 | @item name | |
177c0ea7 | 1350 | The argument, a symbol, is the name of the defining form. |
73804d4b RS |
1351 | |
1352 | A defining form is not required to have a name field; and it may have | |
1353 | multiple name fields. | |
1354 | ||
1355 | @item :name | |
1356 | This construct does not actually match an argument. The element | |
1357 | following @code{:name} should be a symbol; it is used as an additional | |
1358 | name component for the definition. You can use this to add a unique, | |
1359 | static component to the name of the definition. It may be used more | |
1360 | than once. | |
1361 | ||
1362 | @item arg | |
1363 | The argument, a symbol, is the name of an argument of the defining form. | |
a9f0a989 | 1364 | However, lambda-list keywords (symbols starting with @samp{&}) |
87b2d5ff | 1365 | are not allowed. |
73804d4b RS |
1366 | |
1367 | @item lambda-list | |
1368 | @cindex lambda-list (Edebug) | |
1369 | This matches a lambda list---the argument list of a lambda expression. | |
73804d4b RS |
1370 | |
1371 | @item def-body | |
1372 | The argument is the body of code in a definition. This is like | |
1373 | @code{body}, described above, but a definition body must be instrumented | |
1374 | with a different Edebug call that looks up information associated with | |
1375 | the definition. Use @code{def-body} for the highest level list of forms | |
1376 | within the definition. | |
1377 | ||
1378 | @item def-form | |
1379 | The argument is a single, highest-level form in a definition. This is | |
622fa380 | 1380 | like @code{def-body}, except it is used to match a single form rather than |
73804d4b RS |
1381 | a list of forms. As a special case, @code{def-form} also means that |
1382 | tracing information is not output when the form is executed. See the | |
67c1390d | 1383 | @code{interactive} example. |
73804d4b RS |
1384 | @end table |
1385 | ||
1386 | @node Backtracking | |
969fe9b5 | 1387 | @subsubsection Backtracking in Specifications |
73804d4b RS |
1388 | |
1389 | @cindex backtracking | |
1390 | @cindex syntax error (Edebug) | |
1391 | If a specification fails to match at some point, this does not | |
1392 | necessarily mean a syntax error will be signaled; instead, | |
1393 | @dfn{backtracking} will take place until all alternatives have been | |
1394 | exhausted. Eventually every element of the argument list must be | |
1395 | matched by some element in the specification, and every required element | |
1396 | in the specification must match some argument. | |
177c0ea7 | 1397 | |
a9f0a989 | 1398 | When a syntax error is detected, it might not be reported until much |
622fa380 | 1399 | later, after higher-level alternatives have been exhausted, and with the |
a9f0a989 RS |
1400 | point positioned further from the real error. But if backtracking is |
1401 | disabled when an error occurs, it can be reported immediately. Note | |
1402 | that backtracking is also reenabled automatically in several situations; | |
622fa380 GM |
1403 | when a new alternative is established by @code{&optional}, |
1404 | @code{&rest}, or @code{&or}, or at the start of processing a sublist, | |
1405 | group, or indirect specification. The effect of enabling or disabling | |
1406 | backtracking is limited to the remainder of the level currently being | |
1407 | processed and lower levels. | |
a9f0a989 RS |
1408 | |
1409 | Backtracking is disabled while matching any of the | |
1410 | form specifications (that is, @code{form}, @code{body}, @code{def-form}, and | |
73804d4b RS |
1411 | @code{def-body}). These specifications will match any form so any error |
1412 | must be in the form itself rather than at a higher level. | |
1413 | ||
a9f0a989 | 1414 | Backtracking is also disabled after successfully matching a quoted |
73804d4b | 1415 | symbol or string specification, since this usually indicates a |
a9f0a989 | 1416 | recognized construct. But if you have a set of alternative constructs that |
73804d4b RS |
1417 | all begin with the same symbol, you can usually work around this |
1418 | constraint by factoring the symbol out of the alternatives, e.g., | |
1419 | @code{["foo" &or [first case] [second case] ...]}. | |
1420 | ||
3e7274ae | 1421 | Most needs are satisfied by these two ways that backtracking is |
a9f0a989 RS |
1422 | automatically disabled, but occasionally it is useful to explicitly |
1423 | disable backtracking by using the @code{gate} specification. This is | |
1424 | useful when you know that no higher alternatives could apply. See the | |
1425 | example of the @code{let} specification. | |
73804d4b | 1426 | |
73804d4b RS |
1427 | @node Specification Examples |
1428 | @subsubsection Specification Examples | |
1429 | ||
1430 | It may be easier to understand Edebug specifications by studying | |
1431 | the examples provided here. | |
1432 | ||
1433 | A @code{let} special form has a sequence of bindings and a body. Each | |
1434 | of the bindings is either a symbol or a sublist with a symbol and | |
a9f0a989 | 1435 | optional expression. In the specification below, notice the @code{gate} |
73804d4b RS |
1436 | inside of the sublist to prevent backtracking once a sublist is found. |
1437 | ||
0b021094 GM |
1438 | @ignore |
1439 | @c FIXME? The actual definition in edebug.el looks like this (and always | |
1440 | @c has AFAICS). In fact, nothing in edebug.el uses gate. So maybe | |
1441 | @c this is just an example for illustration? | |
1442 | (def-edebug-spec let | |
1443 | ((&rest | |
1444 | &or (symbolp &optional form) symbolp) | |
1445 | body)) | |
1446 | @end ignore | |
73804d4b RS |
1447 | @example |
1448 | (def-edebug-spec let | |
1449 | ((&rest | |
1450 | &or symbolp (gate symbolp &optional form)) | |
1451 | body)) | |
1452 | @end example | |
1453 | ||
622fa380 GM |
1454 | Edebug uses the following specifications for @code{defun} and the |
1455 | associated argument list and @code{interactive} specifications. It is | |
1456 | necessary to handle interactive forms specially since an expression | |
1457 | argument is actually evaluated outside of the function body. (The | |
1458 | specification for @code{defmacro} is very similar to that for | |
1459 | @code{defun}, but allows for the @code{declare} statement.) | |
73804d4b | 1460 | |
87b2d5ff | 1461 | @smallexample |
177c0ea7 JB |
1462 | (def-edebug-spec defun |
1463 | (&define name lambda-list | |
87b2d5ff | 1464 | [&optional stringp] ; @r{Match the doc string, if present.} |
73804d4b RS |
1465 | [&optional ("interactive" interactive)] |
1466 | def-body)) | |
1467 | ||
1468 | (def-edebug-spec lambda-list | |
1469 | (([&rest arg] | |
1470 | [&optional ["&optional" arg &rest arg]] | |
1471 | &optional ["&rest" arg] | |
1472 | ))) | |
1473 | ||
1474 | (def-edebug-spec interactive | |
1475 | (&optional &or stringp def-form)) ; @r{Notice: @code{def-form}} | |
87b2d5ff | 1476 | @end smallexample |
73804d4b RS |
1477 | |
1478 | The specification for backquote below illustrates how to match | |
1479 | dotted lists and use @code{nil} to terminate recursion. It also | |
1480 | illustrates how components of a vector may be matched. (The actual | |
622fa380 GM |
1481 | specification defined by Edebug is a little different, and does not |
1482 | support dotted lists because doing so causes very deep recursion that | |
1483 | could fail.) | |
73804d4b | 1484 | |
87b2d5ff | 1485 | @smallexample |
622fa380 | 1486 | (def-edebug-spec \` (backquote-form)) ; @r{Alias just for clarity.} |
73804d4b RS |
1487 | |
1488 | (def-edebug-spec backquote-form | |
1489 | (&or ([&or "," ",@@"] &or ("quote" backquote-form) form) | |
1490 | (backquote-form . [&or nil backquote-form]) | |
1491 | (vector &rest backquote-form) | |
1492 | sexp)) | |
87b2d5ff | 1493 | @end smallexample |
73804d4b RS |
1494 | |
1495 | ||
1496 | @node Edebug Options | |
1497 | @subsection Edebug Options | |
1498 | ||
1499 | These options affect the behavior of Edebug: | |
622fa380 GM |
1500 | @c Previously defopt'd: |
1501 | @c edebug-sit-for-seconds, edebug-print-length, edebug-print-level | |
1502 | @c edebug-print-circle, edebug-eval-macro-args | |
73804d4b RS |
1503 | |
1504 | @defopt edebug-setup-hook | |
1505 | Functions to call before Edebug is used. Each time it is set to a new | |
1506 | value, Edebug will call those functions once and then | |
650b6d0b GM |
1507 | reset @code{edebug-setup-hook} to @code{nil}. You could use this to |
1508 | load up Edebug specifications associated with a package you are using, | |
73804d4b RS |
1509 | but only when you also use Edebug. |
1510 | @xref{Instrumenting}. | |
1511 | @end defopt | |
1512 | ||
1513 | @defopt edebug-all-defs | |
1514 | If this is non-@code{nil}, normal evaluation of defining forms such as | |
1515 | @code{defun} and @code{defmacro} instruments them for Edebug. This | |
87b2d5ff RS |
1516 | applies to @code{eval-defun}, @code{eval-region}, @code{eval-buffer}, |
1517 | and @code{eval-current-buffer}. | |
1518 | ||
1519 | Use the command @kbd{M-x edebug-all-defs} to toggle the value of this | |
1520 | option. @xref{Instrumenting}. | |
73804d4b RS |
1521 | @end defopt |
1522 | ||
1523 | @defopt edebug-all-forms | |
87b2d5ff RS |
1524 | If this is non-@code{nil}, the commands @code{eval-defun}, |
1525 | @code{eval-region}, @code{eval-buffer}, and @code{eval-current-buffer} | |
1526 | instrument all forms, even those that don't define anything. | |
1527 | This doesn't apply to loading or evaluations in the minibuffer. | |
73804d4b RS |
1528 | |
1529 | Use the command @kbd{M-x edebug-all-forms} to toggle the value of this | |
87b2d5ff | 1530 | option. @xref{Instrumenting}. |
73804d4b RS |
1531 | @end defopt |
1532 | ||
1533 | @defopt edebug-save-windows | |
1534 | If this is non-@code{nil}, Edebug saves and restores the window | |
1535 | configuration. That takes some time, so if your program does not care | |
1536 | what happens to the window configurations, it is better to set this | |
1537 | variable to @code{nil}. | |
1538 | ||
1539 | If the value is a list, only the listed windows are saved and | |
177c0ea7 | 1540 | restored. |
73804d4b RS |
1541 | |
1542 | You can use the @kbd{W} command in Edebug to change this variable | |
1543 | interactively. @xref{Edebug Display Update}. | |
1544 | @end defopt | |
1545 | ||
1546 | @defopt edebug-save-displayed-buffer-points | |
87b2d5ff RS |
1547 | If this is non-@code{nil}, Edebug saves and restores point in all |
1548 | displayed buffers. | |
73804d4b RS |
1549 | |
1550 | Saving and restoring point in other buffers is necessary if you are | |
622fa380 | 1551 | debugging code that changes the point of a buffer that is displayed in |
73804d4b | 1552 | a non-selected window. If Edebug or the user then selects the window, |
87b2d5ff | 1553 | point in that buffer will move to the window's value of point. |
73804d4b RS |
1554 | |
1555 | Saving and restoring point in all buffers is expensive, since it | |
1556 | requires selecting each window twice, so enable this only if you need | |
1557 | it. @xref{Edebug Display Update}. | |
1558 | @end defopt | |
1559 | ||
1560 | @defopt edebug-initial-mode | |
1561 | If this variable is non-@code{nil}, it specifies the initial execution | |
1562 | mode for Edebug when it is first activated. Possible values are | |
1563 | @code{step}, @code{next}, @code{go}, @code{Go-nonstop}, @code{trace}, | |
1564 | @code{Trace-fast}, @code{continue}, and @code{Continue-fast}. | |
1565 | ||
177c0ea7 | 1566 | The default value is @code{step}. |
73804d4b RS |
1567 | @xref{Edebug Execution Modes}. |
1568 | @end defopt | |
1569 | ||
1570 | @defopt edebug-trace | |
42995636 | 1571 | If this is non-@code{nil}, trace each function entry and exit. |
2bb0eca1 | 1572 | Tracing output is displayed in a buffer named @file{*edebug-trace*}, one |
177c0ea7 | 1573 | function entry or exit per line, indented by the recursion level. |
73804d4b | 1574 | |
a9f0a989 | 1575 | Also see @code{edebug-tracing}, in @ref{Trace Buffer}. |
73804d4b RS |
1576 | @end defopt |
1577 | ||
177c0ea7 | 1578 | @defopt edebug-test-coverage |
73804d4b | 1579 | If non-@code{nil}, Edebug tests coverage of all expressions debugged. |
73804d4b RS |
1580 | @xref{Coverage Testing}. |
1581 | @end defopt | |
1582 | ||
177c0ea7 | 1583 | @defopt edebug-continue-kbd-macro |
73804d4b RS |
1584 | If non-@code{nil}, continue defining or executing any keyboard macro |
1585 | that is executing outside of Edebug. Use this with caution since it is not | |
1586 | debugged. | |
1587 | @xref{Edebug Execution Modes}. | |
1588 | @end defopt | |
1589 | ||
0b021094 GM |
1590 | @defopt edebug-unwrap-results |
1591 | If non-@code{nil}, Edebug tries to remove any of its own | |
1592 | instrumentation when showing the results of expressions. This is | |
1593 | relevant when debugging macros where the results of expressions are | |
1594 | themselves instrumented expressions. As a very artificial example, | |
1595 | suppose that the example function @code{fac} has been instrumented, | |
1596 | and consider a macro of the form: | |
1597 | ||
1598 | @c FIXME find a less silly example. | |
1599 | @smallexample | |
1600 | (defmacro test () "Edebug example." | |
1601 | (if (symbol-function 'fac) | |
1602 | @dots{})) | |
1603 | @end smallexample | |
1604 | ||
1605 | If you instrument the @code{test} macro and step through it, then by | |
1606 | default the result of the @code{symbol-function} call has numerous | |
1607 | @code{edebug-after} and @code{edebug-before} forms, which can make it | |
1608 | difficult to see the ``actual'' result. If | |
1609 | @code{edebug-unwrap-results} is non-@code{nil}, Edebug tries to remove | |
1610 | these forms from the result. | |
1611 | @end defopt | |
622fa380 | 1612 | |
73804d4b RS |
1613 | @defopt edebug-on-error |
1614 | Edebug binds @code{debug-on-error} to this value, if | |
1615 | @code{debug-on-error} was previously @code{nil}. @xref{Trapping | |
1616 | Errors}. | |
1617 | @end defopt | |
1618 | ||
1619 | @defopt edebug-on-quit | |
1620 | Edebug binds @code{debug-on-quit} to this value, if | |
1621 | @code{debug-on-quit} was previously @code{nil}. @xref{Trapping | |
1622 | Errors}. | |
1623 | @end defopt | |
1624 | ||
1625 | If you change the values of @code{edebug-on-error} or | |
1626 | @code{edebug-on-quit} while Edebug is active, their values won't be used | |
87b2d5ff RS |
1627 | until the @emph{next} time Edebug is invoked via a new command. |
1628 | @c Not necessarily a deeper command level. | |
1629 | @c A new command is not precisely true, but that is close enough -- dan | |
73804d4b RS |
1630 | |
1631 | @defopt edebug-global-break-condition | |
9a8dc0d3 RS |
1632 | If non-@code{nil}, an expression to test for at every stop point. If |
1633 | the result is non-@code{nil}, then break. Errors are ignored. | |
73804d4b RS |
1634 | @xref{Global Break Condition}. |
1635 | @end defopt |