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8cf51b2c | 1 | @c This is part of the Emacs manual. |
73b0cd50 | 2 | @c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2011 |
8838673e | 3 | @c Free Software Foundation, Inc. |
8cf51b2c GM |
4 | @c See file emacs.texi for copying conditions. |
5 | @node Building, Maintaining, Programs, Top | |
6 | @chapter Compiling and Testing Programs | |
7 | @cindex building programs | |
8 | @cindex program building | |
9 | @cindex running Lisp functions | |
10 | ||
11 | The previous chapter discusses the Emacs commands that are useful for | |
12 | making changes in programs. This chapter deals with commands that assist | |
13 | in the larger process of compiling and testing programs. | |
14 | ||
15 | @menu | |
16 | * Compilation:: Compiling programs in languages other | |
17 | than Lisp (C, Pascal, etc.). | |
18 | * Compilation Mode:: The mode for visiting compiler errors. | |
19 | * Compilation Shell:: Customizing your shell properly | |
20 | for use in the compilation buffer. | |
21 | * Grep Searching:: Searching with grep. | |
22 | * Flymake:: Finding syntax errors on the fly. | |
8838673e | 23 | * Debuggers:: Running symbolic debuggers for non-Lisp programs. |
8cf51b2c GM |
24 | * Executing Lisp:: Various modes for editing Lisp programs, |
25 | with different facilities for running | |
26 | the Lisp programs. | |
27 | * Libraries: Lisp Libraries. Creating Lisp programs to run in Emacs. | |
28 | * Eval: Lisp Eval. Executing a single Lisp expression in Emacs. | |
29 | * Interaction: Lisp Interaction. Executing Lisp in an Emacs buffer. | |
8838673e | 30 | * External Lisp:: Communicating through Emacs with a separate Lisp. |
8cf51b2c GM |
31 | @end menu |
32 | ||
33 | @node Compilation | |
34 | @section Running Compilations under Emacs | |
35 | @cindex inferior process | |
36 | @cindex make | |
37 | @cindex compilation errors | |
38 | @cindex error log | |
39 | ||
40 | Emacs can run compilers for noninteractive languages such as C and | |
41 | Fortran as inferior processes, feeding the error log into an Emacs buffer. | |
42 | It can also parse the error messages and show you the source lines where | |
43 | compilation errors occurred. | |
44 | ||
45 | @table @kbd | |
46 | @item M-x compile | |
47 | Run a compiler asynchronously under Emacs, with error messages going to | |
48 | the @samp{*compilation*} buffer. | |
49 | @item M-x recompile | |
50 | Invoke a compiler with the same command as in the last invocation of | |
51 | @kbd{M-x compile}. | |
52 | @item M-x kill-compilation | |
53 | Kill the running compilation subprocess. | |
54 | @end table | |
55 | ||
56 | @findex compile | |
57 | To run @code{make} or another compilation command, do @kbd{M-x | |
58 | compile}. This command reads a shell command line using the minibuffer, | |
59 | and then executes the command in an inferior shell, putting output in | |
60 | the buffer named @samp{*compilation*}. The current buffer's default | |
61 | directory is used as the working directory for the execution of the | |
62 | command; normally, therefore, the compilation happens in this | |
63 | directory. | |
64 | ||
65 | @vindex compile-command | |
66 | The default for the compilation command is normally @samp{make -k}, | |
67 | which is correct most of the time for nontrivial programs. | |
a03334ca | 68 | @xref{Top,, Make, make, GNU Make Manual}. If you have done @kbd{M-x |
8cf51b2c GM |
69 | compile} before, the default each time is the command you used the |
70 | previous time. @code{compile} stores this command in the variable | |
71 | @code{compile-command}, so setting that variable specifies the default | |
72 | for the next use of @kbd{M-x compile}. If a file specifies a file | |
73 | local value for @code{compile-command}, that provides the default when | |
74 | you type @kbd{M-x compile} in that file's buffer. @xref{File | |
75 | Variables}. | |
76 | ||
77 | Starting a compilation displays the buffer @samp{*compilation*} in | |
78 | another window but does not select it. The buffer's mode line tells | |
79 | you whether compilation is finished, with the word @samp{run}, | |
80 | @samp{signal} or @samp{exit} inside the parentheses. You do not have | |
81 | to keep this buffer visible; compilation continues in any case. While | |
82 | a compilation is going on, the string @samp{Compiling} appears in the | |
83 | mode lines of all windows. When this string disappears, the | |
84 | compilation is finished. | |
85 | ||
86 | If you want to watch the compilation transcript as it appears, switch | |
87 | to the @samp{*compilation*} buffer and move point to the end of the | |
88 | buffer. When point is at the end, new compilation output is inserted | |
89 | above point, which remains at the end. If point is not at the end of | |
90 | the buffer, it remains fixed while more compilation output is added at | |
91 | the end of the buffer. | |
92 | ||
93 | @cindex compilation buffer, keeping point at end | |
94 | @vindex compilation-scroll-output | |
07799e9a CY |
95 | If you change the variable @code{compilation-scroll-output} to a |
96 | non-@code{nil} value, the compilation buffer will scroll automatically | |
97 | to follow the output as it comes in. If the value is | |
98 | @code{first-error}, the scrolling stops at the first error that | |
99 | appears, leaving point at that error. For any other non-@code{nil} | |
100 | value, the buffer continues scrolling until there is no more output. | |
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101 | |
102 | @findex recompile | |
103 | To rerun the last compilation with the same command, type @kbd{M-x | |
104 | recompile}. This automatically reuses the compilation command from | |
105 | the last invocation of @kbd{M-x compile}. It also reuses the | |
106 | @samp{*compilation*} buffer and starts the compilation in its default | |
107 | directory, which is the directory in which the previous compilation | |
108 | was started. | |
109 | ||
110 | When the compiler process terminates, for whatever reason, the mode | |
111 | line of the @samp{*compilation*} buffer changes to say @samp{exit} | |
112 | (followed by the exit code, @samp{[0]} for a normal exit), or | |
113 | @samp{signal} (if a signal terminated the process), instead of | |
114 | @samp{run}. | |
115 | ||
116 | @findex kill-compilation | |
117 | Starting a new compilation also kills any compilation already | |
118 | running in @samp{*compilation*}, as the buffer can only handle one | |
119 | compilation at any time. However, @kbd{M-x compile} asks for | |
120 | confirmation before actually killing a compilation that is running. | |
121 | You can also kill the compilation process with @kbd{M-x | |
122 | kill-compilation}. | |
123 | ||
bb033b5f CY |
124 | To run two compilations at once, start the first one, then rename |
125 | the @samp{*compilation*} buffer (perhaps using @code{rename-uniquely}; | |
126 | @pxref{Misc Buffer}), then switch buffers and start the other | |
127 | compilation. This will create a new @samp{*compilation*} buffer. | |
8cf51b2c GM |
128 | |
129 | Emacs does not expect a compiler process to launch asynchronous | |
130 | subprocesses; if it does, and they keep running after the main | |
131 | compiler process has terminated, Emacs may kill them or their output | |
132 | may not arrive in Emacs. To avoid this problem, make the main process | |
133 | wait for its subprocesses to finish. In a shell script, you can do this | |
134 | using @samp{$!} and @samp{wait}, like this: | |
135 | ||
136 | @example | |
137 | (sleep 10; echo 2nd)& pid=$! # @r{Record pid of subprocess} | |
138 | echo first message | |
139 | wait $pid # @r{Wait for subprocess} | |
140 | @end example | |
141 | ||
142 | If the background process does not output to the compilation buffer, | |
143 | so you only need to prevent it from being killed when the main | |
144 | compilation process terminates, this is sufficient: | |
145 | ||
146 | @example | |
147 | nohup @var{command}; sleep 1 | |
148 | @end example | |
149 | ||
150 | @vindex compilation-environment | |
151 | You can control the environment passed to the compilation command | |
152 | with the variable @code{compilation-environment}. Its value is a list | |
153 | of environment variable settings; each element should be a string of | |
154 | the form @code{"@var{envvarname}=@var{value}"}. These environment | |
155 | variable settings override the usual ones. | |
156 | ||
157 | @node Compilation Mode | |
158 | @section Compilation Mode | |
159 | ||
160 | @cindex Compilation mode | |
161 | @cindex mode, Compilation | |
162 | The @samp{*compilation*} buffer uses a special major mode, | |
163 | Compilation mode, whose main feature is to provide a convenient way to | |
164 | visit the source line corresponding to an error message. These | |
165 | commands are also available in other special buffers that list | |
166 | locations in files, including those made by @kbd{M-x grep} and | |
167 | @kbd{M-x occur}. | |
168 | ||
169 | @table @kbd | |
170 | @item M-g M-n | |
171 | @itemx M-g n | |
172 | @itemx C-x ` | |
173 | Visit the locus of the next error message or match. | |
174 | @item M-g M-p | |
175 | @itemx M-g p | |
176 | Visit the locus of the previous error message or match. | |
177 | @item @key{RET} | |
178 | Visit the locus of the error message that point is on. | |
179 | This command is used in the compilation buffer. | |
180 | @item Mouse-2 | |
181 | Visit the locus of the error message that you click on. | |
182 | @item M-n | |
183 | Find and highlight the locus of the next error message, without | |
184 | selecting the source buffer. | |
185 | @item M-p | |
186 | Find and highlight the locus of the previous error message, without | |
187 | selecting the source buffer. | |
188 | @item M-@} | |
189 | Move point to the next error for a different file than the current | |
190 | one. | |
191 | @item M-@{ | |
192 | Move point to the previous error for a different file than the current | |
193 | one. | |
194 | @item C-c C-f | |
195 | Toggle Next Error Follow minor mode, which makes cursor motion in the | |
196 | compilation buffer produce automatic source display. | |
197 | @end table | |
198 | ||
199 | @findex compile-goto-error | |
a03334ca | 200 | @vindex compilation-auto-jump-to-first-error |
8cf51b2c GM |
201 | You can visit the source for any particular error message by moving |
202 | point in the @samp{*compilation*} buffer to that error message and | |
203 | typing @key{RET} (@code{compile-goto-error}). Alternatively, you can | |
204 | click @kbd{Mouse-2} on the error message; you need not switch to the | |
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205 | @samp{*compilation*} buffer first. If you set the variable |
206 | @code{compilation-auto-jump-to-first-error} to a non-@code{nil} value, | |
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207 | Emacs automatically jumps to the first error, if any, as soon as it |
208 | appears in the @samp{*compilation*} buffer. | |
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209 | |
210 | @kindex M-g M-n | |
211 | @kindex M-g n | |
212 | @kindex C-x ` | |
213 | @findex next-error | |
214 | @vindex next-error-highlight | |
215 | To parse the compiler error messages sequentially, type @kbd{C-x `} | |
216 | (@code{next-error}). The character following the @kbd{C-x} is the | |
217 | backquote or ``grave accent,'' not the single-quote. This command is | |
218 | available in all buffers, not just in @samp{*compilation*}; it | |
219 | displays the next error message at the top of one window and source | |
220 | location of the error in another window. It also temporarily | |
221 | highlights the relevant source line, for a period controlled by the | |
222 | variable @code{next-error-highlight}. | |
223 | ||
224 | The first time @w{@kbd{C-x `}} is used after the start of a compilation, | |
225 | it moves to the first error's location. Subsequent uses of @kbd{C-x | |
226 | `} advance down to subsequent errors. If you visit a specific error | |
227 | message with @key{RET} or @kbd{Mouse-2}, subsequent @w{@kbd{C-x `}} | |
228 | commands advance from there. When @w{@kbd{C-x `}} gets to the end of the | |
229 | buffer and finds no more error messages to visit, it fails and signals | |
230 | an Emacs error. @w{@kbd{C-u C-x `}} starts scanning from the beginning of | |
231 | the compilation buffer, and goes to the first error's location. | |
232 | ||
233 | @vindex compilation-skip-threshold | |
234 | By default, @w{@kbd{C-x `}} skips less important messages. The variable | |
235 | @code{compilation-skip-threshold} controls this. If its value is 2, | |
236 | @w{@kbd{C-x `}} skips anything less than error, 1 skips anything less | |
237 | than warning, and 0 doesn't skip any messages. The default is 1. | |
238 | ||
239 | When the window has a left fringe, an arrow in the fringe points to | |
240 | the current message in the compilation buffer. The variable | |
241 | @code{compilation-context-lines} controls the number of lines of | |
242 | leading context to display before the current message. Going to an | |
243 | error message location scrolls the @samp{*compilation*} buffer to put | |
244 | the message that far down from the top. The value @code{nil} is | |
245 | special: if there's a left fringe, the window doesn't scroll at all | |
246 | if the message is already visible. If there is no left fringe, | |
247 | @code{nil} means display the message at the top of the window. | |
248 | ||
249 | If you're not in the compilation buffer when you run | |
250 | @code{next-error}, Emacs will look for a buffer that contains error | |
251 | messages. First, it looks for one displayed in the selected frame, | |
252 | then for one that previously had @code{next-error} called on it, and | |
253 | then at the current buffer. Finally, Emacs looks at all the remaining | |
254 | buffers. @code{next-error} signals an error if it can't find any such | |
255 | buffer. | |
256 | ||
257 | @vindex compilation-error-regexp-alist | |
258 | @vindex grep-regexp-alist | |
259 | To parse messages from the compiler, Compilation mode uses the | |
260 | variable @code{compilation-error-regexp-alist} which lists various | |
261 | formats of error messages and tells Emacs how to extract the source file | |
262 | and the line number from the text of a message. If your compiler isn't | |
263 | supported, you can tailor Compilation mode to it by adding elements to | |
264 | that list. A similar variable @code{grep-regexp-alist} tells Emacs how | |
265 | to parse output of a @code{grep} command. | |
266 | ||
267 | @findex compilation-next-error | |
268 | @findex compilation-previous-error | |
269 | @findex compilation-next-file | |
270 | @findex compilation-previous-file | |
271 | Compilation mode also redefines the keys @key{SPC} and @key{DEL} to | |
272 | scroll by screenfuls, and @kbd{M-n} (@code{compilation-next-error}) | |
273 | and @kbd{M-p} (@code{compilation-previous-error}) to move to the next | |
274 | or previous error message. You can also use @kbd{M-@{} | |
275 | (@code{compilation-next-file} and @kbd{M-@}} | |
276 | (@code{compilation-previous-file}) to move up or down to an error | |
277 | message for a different source file. | |
278 | ||
279 | @cindex Next Error Follow mode | |
280 | @findex next-error-follow-minor-mode | |
281 | You can type @kbd{C-c C-f} to toggle Next Error Follow mode. In | |
282 | this minor mode, ordinary cursor motion in the compilation buffer | |
283 | automatically updates the source buffer. For instance, moving the | |
284 | cursor to the next error message causes the location of that error to | |
285 | be displayed immediately. | |
286 | ||
287 | The features of Compilation mode are also available in a minor mode | |
288 | called Compilation Minor mode. This lets you parse error messages in | |
289 | any buffer, not just a normal compilation output buffer. Type @kbd{M-x | |
290 | compilation-minor-mode} to enable the minor mode. This defines the keys | |
291 | @key{RET} and @kbd{Mouse-2}, as in the Compilation major mode. | |
292 | ||
293 | Compilation minor mode works in any buffer, as long as the contents | |
294 | are in a format that it understands. In an Rlogin buffer (@pxref{Remote | |
295 | Host}), Compilation minor mode automatically accesses remote source | |
296 | files by FTP (@pxref{File Names}). | |
297 | ||
298 | @node Compilation Shell | |
299 | @section Subshells for Compilation | |
300 | ||
301 | Emacs uses a shell to run the compilation command, but specifies the | |
302 | option for a noninteractive shell. This means, in particular, that | |
303 | the shell should start with no prompt. If you find your usual shell | |
304 | prompt making an unsightly appearance in the @samp{*compilation*} | |
305 | buffer, it means you have made a mistake in your shell's init file by | |
306 | setting the prompt unconditionally. (This init file's name may be | |
307 | @file{.bashrc}, @file{.profile}, @file{.cshrc}, @file{.shrc}, or | |
308 | various other things, depending on the shell you use.) The shell init | |
309 | file should set the prompt only if there already is a prompt. Here's | |
310 | how to do it in bash: | |
311 | ||
312 | @example | |
313 | if [ "$@{PS1+set@}" = set ] | |
314 | then PS1=@dots{} | |
315 | fi | |
316 | @end example | |
317 | ||
318 | @noindent | |
319 | And here's how to do it in csh: | |
320 | ||
321 | @example | |
322 | if ($?prompt) set prompt = @dots{} | |
323 | @end example | |
324 | ||
325 | There may well be other things that your shell's init file | |
326 | ought to do only for an interactive shell. You can use the same | |
327 | method to conditionalize them. | |
328 | ||
329 | The MS-DOS ``operating system'' does not support asynchronous | |
330 | subprocesses; to work around this lack, @kbd{M-x compile} runs the | |
331 | compilation command synchronously on MS-DOS. As a consequence, you must | |
332 | wait until the command finishes before you can do anything else in | |
333 | Emacs. | |
334 | @iftex | |
335 | @inforef{MS-DOS,,emacs-xtra}. | |
336 | @end iftex | |
337 | @ifnottex | |
338 | @xref{MS-DOS}. | |
339 | @end ifnottex | |
340 | ||
341 | @node Grep Searching | |
342 | @section Searching with Grep under Emacs | |
343 | ||
344 | Just as you can run a compiler from Emacs and then visit the lines | |
345 | with compilation errors, you can also run @code{grep} and then visit | |
346 | the lines on which matches were found. This works by treating the | |
347 | matches reported by @code{grep} as if they were ``errors.'' The | |
348 | buffer of matches uses Grep mode, which is a variant of Compilation | |
349 | mode (@pxref{Compilation Mode}). | |
350 | ||
351 | @table @kbd | |
352 | @item M-x grep | |
467e8d77 | 353 | @itemx M-x lgrep |
8cf51b2c GM |
354 | Run @code{grep} asynchronously under Emacs, with matching lines |
355 | listed in the buffer named @samp{*grep*}. | |
356 | @item M-x grep-find | |
357 | @itemx M-x find-grep | |
358 | @itemx M-x rgrep | |
26e533e2 CY |
359 | Run @code{grep} via @code{find}, and collect output in the buffer |
360 | named @samp{*grep*}. | |
361 | @item M-x zrgrep | |
362 | Run @code{zgrep} and collect output in the buffer named @samp{*grep*}. | |
8cf51b2c GM |
363 | @item M-x kill-grep |
364 | Kill the running @code{grep} subprocess. | |
365 | @end table | |
366 | ||
367 | @findex grep | |
368 | To run @code{grep}, type @kbd{M-x grep}, then enter a command line | |
369 | that specifies how to run @code{grep}. Use the same arguments you | |
370 | would give @code{grep} when running it normally: a @code{grep}-style | |
371 | regexp (usually in single-quotes to quote the shell's special | |
372 | characters) followed by file names, which may use wildcards. If you | |
373 | specify a prefix argument for @kbd{M-x grep}, it finds the tag | |
374 | (@pxref{Tags}) in the buffer around point, and puts that into the | |
375 | default @code{grep} command. | |
376 | ||
377 | Your command need not simply run @code{grep}; you can use any shell | |
378 | command that produces output in the same format. For instance, you | |
379 | can chain @code{grep} commands, like this: | |
380 | ||
381 | @example | |
382 | grep -nH -e foo *.el | grep bar | grep toto | |
383 | @end example | |
384 | ||
385 | The output from @code{grep} goes in the @samp{*grep*} buffer. You | |
386 | can find the corresponding lines in the original files using @w{@kbd{C-x | |
387 | `}}, @key{RET}, and so forth, just like compilation errors. | |
388 | ||
389 | Some grep programs accept a @samp{--color} option to output special | |
390 | markers around matches for the purpose of highlighting. You can make | |
391 | use of this feature by setting @code{grep-highlight-matches} to | |
392 | @code{t}. When displaying a match in the source buffer, the exact | |
393 | match will be highlighted, instead of the entire source line. | |
394 | ||
395 | @findex grep-find | |
396 | @findex find-grep | |
397 | The command @kbd{M-x grep-find} (also available as @kbd{M-x | |
398 | find-grep}) is similar to @kbd{M-x grep}, but it supplies a different | |
399 | initial default for the command---one that runs both @code{find} and | |
400 | @code{grep}, so as to search every file in a directory tree. See also | |
401 | the @code{find-grep-dired} command, in @ref{Dired and Find}. | |
402 | ||
403 | @findex lgrep | |
404 | @findex rgrep | |
26e533e2 | 405 | @findex zrgrep |
8cf51b2c GM |
406 | The commands @kbd{M-x lgrep} (local grep) and @kbd{M-x rgrep} |
407 | (recursive grep) are more user-friendly versions of @code{grep} and | |
408 | @code{grep-find}, which prompt separately for the regular expression | |
409 | to match, the files to search, and the base directory for the search. | |
26e533e2 CY |
410 | Case sensitivity of the search is controlled by the current value of |
411 | @code{case-fold-search}. The command @kbd{M-x zrgrep} is similar to | |
412 | @code{rgrep}, but it calls @code{zgrep} instead of @code{grep} to | |
413 | search the contents of gzipped files. | |
8cf51b2c | 414 | |
26e533e2 | 415 | These commands build the shell commands based on the variables |
8cf51b2c | 416 | @code{grep-template} (for @code{lgrep}) and @code{grep-find-template} |
26e533e2 CY |
417 | (for @code{rgrep}). The files to search can use aliases defined in |
418 | the variable @code{grep-files-aliases}. | |
8cf51b2c | 419 | |
26e533e2 | 420 | Subdirectories listed in the variable |
8cf51b2c GM |
421 | @code{grep-find-ignored-directories} such as those typically used by |
422 | various version control systems, like CVS and arch, are automatically | |
423 | skipped by @code{rgrep}. | |
424 | ||
425 | @node Flymake | |
426 | @section Finding Syntax Errors On The Fly | |
427 | @cindex checking syntax | |
428 | ||
429 | Flymake mode is a minor mode that performs on-the-fly syntax | |
430 | checking for many programming and markup languages, including C, C++, | |
431 | Perl, HTML, and @TeX{}/La@TeX{}. It is somewhat analogous to Flyspell | |
432 | mode, which performs spell checking for ordinary human languages in a | |
433 | similar fashion (@pxref{Spelling}). As you edit a file, Flymake mode | |
434 | runs an appropriate syntax checking tool in the background, using a | |
435 | temporary copy of the buffer. It then parses the error and warning | |
436 | messages, and highlights the erroneous lines in the buffer. The | |
437 | syntax checking tool used depends on the language; for example, for | |
438 | C/C++ files this is usually the C compiler. Flymake can also use | |
439 | build tools such as @code{make} for checking complicated projects. | |
440 | ||
ae742cb5 CY |
441 | To enable Flymake mode, type @kbd{M-x flymake-mode}. You can go to |
442 | the errors found by Flymake mode with @kbd{M-x | |
8cf51b2c GM |
443 | flymake-goto-next-error} and @kbd{M-x flymake-goto-prev-error}. To |
444 | display any error messages associated with the current line, use | |
445 | @kbd{M-x flymake-display-err-menu-for-current-line}. | |
446 | ||
447 | For more details about using Flymake, see @ref{Top, Flymake, | |
448 | Flymake, flymake, The Flymake Manual}. | |
449 | ||
450 | @node Debuggers | |
451 | @section Running Debuggers Under Emacs | |
452 | @cindex debuggers | |
453 | @cindex GUD library | |
454 | @cindex GDB | |
455 | @cindex DBX | |
456 | @cindex SDB | |
457 | @cindex XDB | |
458 | @cindex Perldb | |
459 | @cindex JDB | |
460 | @cindex PDB | |
461 | ||
462 | @c Do you believe in GUD? | |
a03334ca CY |
463 | The GUD (Grand Unified Debugger) library provides an Emacs interface |
464 | to a wide variety of symbolic debuggers. Unlike the GDB graphical | |
465 | interface, which only runs GDB (@pxref{GDB Graphical Interface}), GUD | |
466 | can also run DBX, SDB, XDB, Perl's debugging mode, the Python debugger | |
467 | PDB, or the Java Debugger JDB. | |
8cf51b2c | 468 | |
d35fdb5b NR |
469 | In addition, Emacs contains a built-in system for debugging Emacs |
470 | Lisp programs. @xref{Debugging,, The Lisp Debugger, elisp, the Emacs | |
471 | Lisp Reference Manual}, for information on the Emacs Lisp debugger. | |
472 | ||
8cf51b2c | 473 | @menu |
8838673e GM |
474 | * Starting GUD:: How to start a debugger subprocess. |
475 | * Debugger Operation:: Connection between the debugger and source buffers. | |
476 | * Commands of GUD:: Key bindings for common commands. | |
477 | * GUD Customization:: Defining your own commands for GUD. | |
b424697f NR |
478 | * GDB Graphical Interface:: An enhanced mode that uses GDB features to |
479 | implement a graphical debugging environment through | |
480 | Emacs. | |
8cf51b2c GM |
481 | @end menu |
482 | ||
483 | @node Starting GUD | |
b424697f | 484 | @subsection Starting GUD |
8cf51b2c | 485 | |
a03334ca CY |
486 | There are several commands for starting a debugger under GUD, each |
487 | corresponding to a particular debugger program. | |
8cf51b2c GM |
488 | |
489 | @table @kbd | |
b424697f NR |
490 | @item M-x gdb @key{RET} @var{file} @key{RET} |
491 | @findex gdb | |
492 | Run GDB as a subprocess of Emacs. This uses an IDE-like graphical | |
493 | interface; see @ref{GDB Graphical Interface}. Only GDB works with the | |
494 | graphical interface. | |
495 | ||
4f45c619 NR |
496 | @item M-x gud-gdb @key{RET} @var{file} @key{RET} |
497 | @findex gud-gdb | |
498 | Run GDB as a subprocess of Emacs. This command creates a buffer for | |
499 | input and output to GDB, and switches to it. If a GDB buffer already | |
b424697f | 500 | exists, it just switches to that buffer. |
8cf51b2c GM |
501 | |
502 | @item M-x dbx @key{RET} @var{file} @key{RET} | |
503 | @findex dbx | |
b424697f NR |
504 | Run DBX as a subprocess of Emacs. Since Emacs does not implement a |
505 | graphical interface for DBX, communication with DBX works by typing | |
506 | commands in the GUD interaction buffer. The same is true for all | |
507 | the other supported debuggers. | |
8cf51b2c GM |
508 | |
509 | @item M-x xdb @key{RET} @var{file} @key{RET} | |
510 | @findex xdb | |
511 | @vindex gud-xdb-directories | |
a03334ca | 512 | Run XDB as a subprocess of Emacs. Use the variable |
8cf51b2c GM |
513 | @code{gud-xdb-directories} to specify directories to search for source |
514 | files. | |
515 | ||
516 | @item M-x sdb @key{RET} @var{file} @key{RET} | |
517 | @findex sdb | |
a03334ca | 518 | Run SDB as a subprocess of Emacs. |
8cf51b2c | 519 | |
a03334ca | 520 | Some versions of SDB do not mention source file names in their |
8cf51b2c GM |
521 | messages. When you use them, you need to have a valid tags table |
522 | (@pxref{Tags}) in order for GUD to find functions in the source code. | |
a03334ca CY |
523 | If you have not visited a tags table or the tags table doesn't list |
524 | one of the functions, you get a message saying @samp{The sdb support | |
525 | requires a valid tags table to work}. If this happens, generate a | |
526 | valid tags table in the working directory and try again. | |
8cf51b2c GM |
527 | |
528 | @item M-x perldb @key{RET} @var{file} @key{RET} | |
529 | @findex perldb | |
530 | Run the Perl interpreter in debug mode to debug @var{file}, a Perl program. | |
531 | ||
532 | @item M-x jdb @key{RET} @var{file} @key{RET} | |
533 | @findex jdb | |
534 | Run the Java debugger to debug @var{file}. | |
535 | ||
536 | @item M-x pdb @key{RET} @var{file} @key{RET} | |
537 | @findex pdb | |
538 | Run the Python debugger to debug @var{file}. | |
539 | @end table | |
540 | ||
541 | Each of these commands takes one argument: a command line to invoke | |
542 | the debugger. In the simplest case, specify just the name of the | |
543 | executable file you want to debug. You may also use options that the | |
544 | debugger supports. However, shell wildcards and variables are not | |
545 | allowed. GUD assumes that the first argument not starting with a | |
546 | @samp{-} is the executable file name. | |
547 | ||
a03334ca | 548 | @cindex remote host, debugging on |
7af517e7 EZ |
549 | Tramp provides a facility to debug programs on remote hosts |
550 | (@pxref{Running a debugger on a remote host, Running a debugger on a | |
551 | remote host,, tramp, The Tramp Manual}), whereby both the debugger and | |
552 | the program being debugged are on the same remote host. This should | |
553 | not be confused with debugging programs remotely, where the program | |
554 | and the debugger run on different machines, as can be done using the | |
555 | GDB remote debugging feature, for example (@pxref{Remote Debugging,, | |
556 | Debugging Remote Programs, gdb, The GNU debugger}). | |
8cf51b2c GM |
557 | |
558 | @node Debugger Operation | |
b424697f | 559 | @subsection Debugger Operation |
8cf51b2c GM |
560 | |
561 | @cindex fringes, and current execution line in GUD | |
562 | Generally when you run a debugger with GUD, the debugger uses an Emacs | |
563 | buffer for its ordinary input and output. This is called the GUD | |
564 | buffer. Input and output from the program you are debugging also use | |
565 | this buffer. We call this @dfn{text command mode}. The GDB Graphical | |
566 | Interface can use further buffers (@pxref{GDB Graphical Interface}). | |
567 | ||
568 | The debugger displays the source files of the program by visiting | |
569 | them in Emacs buffers. An arrow in the left fringe indicates the | |
570 | current execution line.@footnote{On a text-only terminal, the arrow | |
571 | appears as @samp{=>} and overlays the first two text columns.} Moving | |
572 | point in this buffer does not move the arrow. The arrow is not part | |
573 | of the file's text; it appears only on the screen. | |
574 | ||
575 | You can start editing these source files at any time in the buffers | |
576 | that display them. If you do modify a source file, keep in mind that | |
577 | inserting or deleting lines will throw off the arrow's positioning; | |
578 | GUD has no way of figuring out which line corresponded before your | |
579 | changes to the line number in a debugger message. Also, you'll | |
580 | typically have to recompile and restart the program for your changes | |
581 | to be reflected in the debugger's tables. | |
582 | ||
583 | @cindex tooltips with GUD | |
584 | @vindex tooltip-gud-modes | |
585 | @vindex gud-tooltip-mode | |
586 | @vindex gud-tooltip-echo-area | |
587 | The Tooltip facility (@pxref{Tooltips}) provides support for GUD@. | |
588 | You activate this feature by turning on the minor mode | |
589 | @code{gud-tooltip-mode}. Then you can display a variable's value in a | |
590 | tooltip simply by pointing at it with the mouse. This operates in the | |
591 | GUD buffer and in source buffers with major modes in the list | |
592 | @code{gud-tooltip-modes}. If the variable @code{gud-tooltip-echo-area} | |
593 | is non-@code{nil} then the variable's value is displayed in the echo | |
594 | area. When debugging a C program using the GDB Graphical Interface, you | |
595 | can also display macro definitions associated with an identifier when | |
596 | the program is not executing. | |
597 | ||
598 | GUD tooltips are disabled when you use GDB in text command mode | |
599 | (@pxref{GDB Graphical Interface}), because displaying an expression's | |
600 | value in GDB can sometimes expand a macro and result in a side effect | |
601 | that interferes with the program's operation. The GDB graphical | |
602 | interface supports GUD tooltips and assures they will not cause side | |
603 | effects. | |
604 | ||
605 | @node Commands of GUD | |
b424697f | 606 | @subsection Commands of GUD |
8cf51b2c GM |
607 | |
608 | The GUD interaction buffer uses a variant of Shell mode, so the | |
609 | Emacs commands of Shell mode are available (@pxref{Shell Mode}). All | |
610 | the usual commands for your debugger are available, and you can use | |
611 | the Shell mode history commands to repeat them. If you wish, you can | |
612 | control your debugger process entirely through this buffer. | |
613 | ||
614 | GUD mode also provides commands for setting and clearing | |
615 | breakpoints, for selecting stack frames, and for stepping through the | |
616 | program. These commands are available both in the GUD buffer and | |
617 | globally, but with different key bindings. It also has its own tool | |
618 | bar from which you can invoke the more common commands by clicking on | |
619 | the appropriate icon. This is particularly useful for repetitive | |
620 | commands like @code{gud-next} and @code{gud-step}, and allows you to | |
621 | keep the GUD buffer hidden. | |
622 | ||
623 | The breakpoint commands are normally used in source file buffers, | |
624 | because that is the easiest way to specify where to set or clear the | |
625 | breakpoint. Here's the global command to set a breakpoint: | |
626 | ||
627 | @table @kbd | |
628 | @item C-x @key{SPC} | |
629 | @kindex C-x SPC | |
630 | Set a breakpoint on the source line that point is on. | |
631 | @end table | |
632 | ||
633 | @kindex C-x C-a @r{(GUD)} | |
634 | Here are the other special commands provided by GUD@. The keys | |
635 | starting with @kbd{C-c} are available only in the GUD interaction | |
636 | buffer. The key bindings that start with @kbd{C-x C-a} are available | |
637 | in the GUD interaction buffer and also in source files. Some of these | |
638 | commands are not available to all the supported debuggers. | |
639 | ||
640 | @table @kbd | |
641 | @item C-c C-l | |
642 | @kindex C-c C-l @r{(GUD)} | |
643 | @itemx C-x C-a C-l | |
644 | @findex gud-refresh | |
645 | Display in another window the last line referred to in the GUD | |
646 | buffer (that is, the line indicated in the last location message). | |
647 | This runs the command @code{gud-refresh}. | |
648 | ||
649 | @item C-c C-s | |
650 | @kindex C-c C-s @r{(GUD)} | |
651 | @itemx C-x C-a C-s | |
652 | @findex gud-step | |
653 | Execute a single line of code (@code{gud-step}). If the line contains | |
654 | a function call, execution stops after entering the called function. | |
655 | ||
656 | @item C-c C-n | |
657 | @kindex C-c C-n @r{(GUD)} | |
658 | @itemx C-x C-a C-n | |
659 | @findex gud-next | |
660 | Execute a single line of code, stepping across entire function calls | |
661 | at full speed (@code{gud-next}). | |
662 | ||
663 | @item C-c C-i | |
664 | @kindex C-c C-i @r{(GUD)} | |
665 | @itemx C-x C-a C-i | |
666 | @findex gud-stepi | |
667 | Execute a single machine instruction (@code{gud-stepi}). | |
668 | ||
669 | @item C-c C-p | |
670 | @kindex C-c C-p @r{(GUD)} | |
671 | @itemx C-x C-a C-p | |
672 | @findex gud-print | |
673 | Evaluate the expression at point (@code{gud-print}). If Emacs | |
674 | does not print the exact expression that you want, mark it as a region | |
675 | first. | |
676 | ||
677 | @need 3000 | |
678 | @item C-c C-r | |
679 | @kindex C-c C-r @r{(GUD)} | |
680 | @itemx C-x C-a C-r | |
681 | @findex gud-cont | |
682 | Continue execution without specifying any stopping point. The program | |
683 | will run until it hits a breakpoint, terminates, or gets a signal that | |
684 | the debugger is checking for (@code{gud-cont}). | |
685 | ||
686 | @need 1000 | |
687 | @item C-c C-d | |
688 | @kindex C-c C-d @r{(GUD)} | |
689 | @itemx C-x C-a C-d | |
690 | @findex gud-remove | |
691 | Delete the breakpoint(s) on the current source line, if any | |
692 | (@code{gud-remove}). If you use this command in the GUD interaction | |
693 | buffer, it applies to the line where the program last stopped. | |
694 | ||
695 | @item C-c C-t | |
696 | @kindex C-c C-t @r{(GUD)} | |
697 | @itemx C-x C-a C-t | |
698 | @findex gud-tbreak | |
699 | Set a temporary breakpoint on the current source line, if any | |
700 | (@code{gud-tbreak}). If you use this command in the GUD interaction | |
701 | buffer, it applies to the line where the program last stopped. | |
702 | ||
703 | @item C-c < | |
704 | @kindex C-c < @r{(GUD)} | |
705 | @itemx C-x C-a < | |
706 | @findex gud-up | |
707 | Select the next enclosing stack frame (@code{gud-up}). This is | |
708 | equivalent to the GDB command @samp{up}. | |
709 | ||
710 | @item C-c > | |
711 | @kindex C-c > @r{(GUD)} | |
712 | @itemx C-x C-a > | |
713 | @findex gud-down | |
714 | Select the next inner stack frame (@code{gud-down}). This is | |
715 | equivalent to the GDB command @samp{down}. | |
716 | ||
717 | @item C-c C-u | |
718 | @kindex C-c C-u @r{(GUD)} | |
719 | @itemx C-x C-a C-u | |
720 | @findex gud-until | |
721 | Continue execution to the current line (@code{gud-until}). The | |
722 | program will run until it hits a breakpoint, terminates, gets a signal | |
723 | that the debugger is checking for, or reaches the line on which the | |
724 | cursor currently sits. | |
725 | ||
726 | @item C-c C-f | |
727 | @kindex C-c C-f @r{(GUD)} | |
728 | @itemx C-x C-a C-f | |
729 | @findex gud-finish | |
730 | Run the program until the selected stack frame returns or | |
731 | stops for some other reason (@code{gud-finish}). | |
732 | @end table | |
733 | ||
734 | If you are using GDB, these additional key bindings are available: | |
735 | ||
736 | @table @kbd | |
737 | @item C-x C-a C-j | |
738 | @kindex C-x C-a C-j @r{(GUD)} | |
739 | @findex gud-jump | |
740 | Only useful in a source buffer, @code{gud-jump} transfers the | |
741 | program's execution point to the current line. In other words, the | |
742 | next line that the program executes will be the one where you gave the | |
743 | command. If the new execution line is in a different function from | |
744 | the previously one, GDB prompts for confirmation since the results may | |
745 | be bizarre. See the GDB manual entry regarding @code{jump} for | |
746 | details. | |
747 | ||
748 | @item @key{TAB} | |
749 | @kindex TAB @r{(GUD)} | |
750 | @findex gud-gdb-complete-command | |
751 | With GDB, complete a symbol name (@code{gud-gdb-complete-command}). | |
752 | This key is available only in the GUD interaction buffer. | |
753 | @end table | |
754 | ||
755 | These commands interpret a numeric argument as a repeat count, when | |
756 | that makes sense. | |
757 | ||
758 | Because @key{TAB} serves as a completion command, you can't use it to | |
759 | enter a tab as input to the program you are debugging with GDB. | |
760 | Instead, type @kbd{C-q @key{TAB}} to enter a tab. | |
761 | ||
762 | @node GUD Customization | |
b424697f | 763 | @subsection GUD Customization |
8cf51b2c GM |
764 | |
765 | @vindex gdb-mode-hook | |
766 | @vindex dbx-mode-hook | |
767 | @vindex sdb-mode-hook | |
768 | @vindex xdb-mode-hook | |
769 | @vindex perldb-mode-hook | |
770 | @vindex pdb-mode-hook | |
771 | @vindex jdb-mode-hook | |
772 | On startup, GUD runs one of the following hooks: @code{gdb-mode-hook}, | |
773 | if you are using GDB; @code{dbx-mode-hook}, if you are using DBX; | |
774 | @code{sdb-mode-hook}, if you are using SDB; @code{xdb-mode-hook}, if you | |
775 | are using XDB; @code{perldb-mode-hook}, for Perl debugging mode; | |
776 | @code{pdb-mode-hook}, for PDB; @code{jdb-mode-hook}, for JDB. You can | |
777 | use these hooks to define custom key bindings for the debugger | |
778 | interaction buffer. @xref{Hooks}. | |
779 | ||
780 | Here is a convenient way to define a command that sends a particular | |
781 | command string to the debugger, and set up a key binding for it in the | |
782 | debugger interaction buffer: | |
783 | ||
784 | @findex gud-def | |
785 | @example | |
786 | (gud-def @var{function} @var{cmdstring} @var{binding} @var{docstring}) | |
787 | @end example | |
788 | ||
789 | This defines a command named @var{function} which sends | |
790 | @var{cmdstring} to the debugger process, and gives it the documentation | |
791 | string @var{docstring}. You can then use the command @var{function} in any | |
792 | buffer. If @var{binding} is non-@code{nil}, @code{gud-def} also binds | |
793 | the command to @kbd{C-c @var{binding}} in the GUD buffer's mode and to | |
794 | @kbd{C-x C-a @var{binding}} generally. | |
795 | ||
796 | The command string @var{cmdstring} may contain certain | |
797 | @samp{%}-sequences that stand for data to be filled in at the time | |
798 | @var{function} is called: | |
799 | ||
800 | @table @samp | |
801 | @item %f | |
802 | The name of the current source file. If the current buffer is the GUD | |
803 | buffer, then the ``current source file'' is the file that the program | |
804 | stopped in. | |
805 | ||
806 | @item %l | |
807 | The number of the current source line. If the current buffer is the GUD | |
808 | buffer, then the ``current source line'' is the line that the program | |
809 | stopped in. | |
810 | ||
811 | @item %e | |
812 | In transient-mark-mode the text in the region, if it is active. | |
813 | Otherwise the text of the C lvalue or function-call expression at or | |
814 | adjacent to point. | |
815 | ||
816 | @item %a | |
817 | The text of the hexadecimal address at or adjacent to point. | |
818 | ||
819 | @item %p | |
820 | The numeric argument of the called function, as a decimal number. If | |
821 | the command is used without a numeric argument, @samp{%p} stands for the | |
822 | empty string. | |
823 | ||
824 | If you don't use @samp{%p} in the command string, the command you define | |
825 | ignores any numeric argument. | |
826 | ||
827 | @item %d | |
828 | The name of the directory of the current source file. | |
829 | ||
830 | @item %c | |
831 | Fully qualified class name derived from the expression surrounding point | |
832 | (jdb only). | |
833 | @end table | |
834 | ||
835 | @node GDB Graphical Interface | |
836 | @subsection GDB Graphical Interface | |
837 | ||
a03334ca | 838 | The command @code{gdb} starts GDB in a graphical interface, using |
abb777ac CY |
839 | Emacs windows for display program state information. With it, you do |
840 | not need to use textual GDB commands; you can control the debugging | |
841 | session with the mouse. For example, you can click in the fringe of a | |
842 | source buffer to set a breakpoint there, or on a stack frame in the | |
843 | stack buffer to select that frame. | |
8cf51b2c GM |
844 | |
845 | This mode requires telling GDB that its ``screen size'' is | |
846 | unlimited, so it sets the height and width accordingly. For correct | |
847 | operation you must not change these values during the GDB session. | |
848 | ||
849 | @vindex gud-gdb-command-name | |
4f45c619 NR |
850 | To run GDB in text command mode, like the other debuggers in Emacs, |
851 | use @kbd{M-x gud-gdb}. You need to use text command mode to debug | |
852 | multiple programs within one Emacs session. | |
8cf51b2c GM |
853 | |
854 | @menu | |
691cf4a0 | 855 | * GDB User Interface Layout:: Control the number of displayed buffers. |
8cf51b2c GM |
856 | * Source Buffers:: Use the mouse in the fringe/margin to |
857 | control your program. | |
858 | * Breakpoints Buffer:: A breakpoint control panel. | |
691cf4a0 | 859 | * Threads Buffer:: Displays your threads. |
8cf51b2c | 860 | * Stack Buffer:: Select a frame from the call stack. |
691cf4a0 | 861 | * Other GDB Buffers:: Input/output, locals, registers, |
8cf51b2c GM |
862 | assembler, threads and memory buffers. |
863 | * Watch Expressions:: Monitor variable values in the speedbar. | |
691cf4a0 | 864 | * Multithreaded Debugging:: Debugging programs with several threads. |
8cf51b2c GM |
865 | @end menu |
866 | ||
691cf4a0 | 867 | @node GDB User Interface Layout |
8cf51b2c GM |
868 | @subsubsection GDB User Interface Layout |
869 | @cindex GDB User Interface layout | |
870 | ||
871 | @vindex gdb-many-windows | |
872 | If the variable @code{gdb-many-windows} is @code{nil} (the default | |
873 | value) then @kbd{M-x gdb} normally displays only the GUD buffer. | |
874 | However, if the variable @code{gdb-show-main} is also non-@code{nil}, | |
875 | it starts with two windows: one displaying the GUD buffer, and the | |
876 | other showing the source for the @code{main} function of the program | |
877 | you are debugging. | |
878 | ||
879 | If @code{gdb-many-windows} is non-@code{nil}, then @kbd{M-x gdb} | |
880 | displays the following frame layout: | |
881 | ||
882 | @smallexample | |
883 | @group | |
884 | +--------------------------------+--------------------------------+ | |
1a19cb6a | 885 | | GUD buffer (I/O of GDB) | Locals/Registers buffer | |
8cf51b2c GM |
886 | |--------------------------------+--------------------------------+ |
887 | | Primary Source buffer | I/O buffer for debugged pgm | | |
888 | |--------------------------------+--------------------------------+ | |
0df6175c | 889 | | Stack buffer | Breakpoints/Threads buffer | |
8cf51b2c GM |
890 | +--------------------------------+--------------------------------+ |
891 | @end group | |
892 | @end smallexample | |
893 | ||
894 | However, if @code{gdb-use-separate-io-buffer} is @code{nil}, the I/O | |
895 | buffer does not appear and the primary source buffer occupies the full | |
896 | width of the frame. | |
897 | ||
898 | @findex gdb-restore-windows | |
899 | If you change the window layout, for example, while editing and | |
900 | re-compiling your program, then you can restore this standard window | |
901 | layout with the command @code{gdb-restore-windows}. | |
902 | ||
903 | @findex gdb-many-windows | |
904 | To switch between this standard layout and a simple layout | |
905 | containing just the GUD buffer and a source file, type @kbd{M-x | |
906 | gdb-many-windows}. | |
907 | ||
908 | You may also specify additional GDB-related buffers to display, | |
909 | either in the same frame or a different one. Select the buffers you | |
8d6bb99e | 910 | want with the @samp{GUD->GDB-Windows} and @samp{GUD->GDB-Frames} |
8cf51b2c GM |
911 | sub-menus. If the menu-bar is unavailable, type @code{M-x |
912 | gdb-display-@var{buffertype}-buffer} or @code{M-x | |
913 | gdb-frame-@var{buffertype}-buffer} respectively, where | |
914 | @var{buffertype} is the relevant buffer type, such as | |
915 | @samp{breakpoints}. Most of these buffers are read-only, and typing | |
916 | @kbd{q} in them kills them. | |
917 | ||
918 | When you finish debugging, kill the GUD buffer with @kbd{C-x k}, | |
919 | which will also kill all the buffers associated with the session. | |
920 | However you need not do this if, after editing and re-compiling your | |
921 | source code within Emacs, you wish continue debugging. When you | |
922 | restart execution, GDB will automatically find your new executable. | |
923 | Keeping the GUD buffer has the advantage of keeping the shell history | |
924 | as well as GDB's breakpoints. You do need to check that the | |
925 | breakpoints in recently edited source files are still in the right | |
926 | places. | |
927 | ||
928 | @node Source Buffers | |
929 | @subsubsection Source Buffers | |
930 | @cindex GDB commands in Fringe | |
931 | ||
932 | @c @findex gdb-mouse-set-clear-breakpoint | |
933 | @c @findex gdb-mouse-toggle-breakpoint | |
d9c4c999 | 934 | Many GDB commands can be entered using key bindings or the tool bar but |
8cf51b2c GM |
935 | sometimes it is quicker to use the fringe. These commands either |
936 | manipulate breakpoints or control program execution. When there is no | |
937 | fringe, you can use the margin but this is only present when the | |
938 | source file already has a breakpoint. | |
939 | ||
940 | You can click @kbd{Mouse-1} in the fringe or display margin of a | |
941 | source buffer to set a breakpoint there and, on a graphical display, a | |
942 | red bullet will appear on that line. If a breakpoint already exists | |
943 | on that line, the same click will remove it. You can also enable or | |
944 | disable a breakpoint by clicking @kbd{C-Mouse-1} on the bullet. | |
945 | ||
946 | A solid arrow in the left fringe of a source buffer indicates the line | |
947 | of the innermost frame where the debugged program has stopped. A | |
948 | hollow arrow indicates the current execution line of higher level | |
949 | frames. | |
950 | ||
951 | If you drag the arrow in the fringe with @kbd{Mouse-1} | |
952 | (@code{gdb-mouse-until}), execution will continue to the line where | |
953 | you release the button, provided it is still in the same frame. | |
954 | Alternatively, you can click @kbd{Mouse-3} at some point in the fringe | |
955 | of this buffer and execution will advance to there. A similar command | |
956 | (@code{gdb-mouse-jump}) allows you to jump to a source line without | |
957 | executing the intermediate lines by clicking @kbd{C-Mouse-3}. This | |
958 | command allows you to go backwards which can be useful for running | |
959 | through code that has already executed, in order to examine its | |
960 | execution in more detail. | |
961 | ||
962 | @table @kbd | |
963 | @item Mouse-1 | |
964 | Set or clear a breakpoint. | |
965 | ||
966 | @item C-Mouse-1 | |
967 | Enable or disable a breakpoint. | |
968 | ||
969 | @item Mouse-3 | |
970 | Continue execution to here. | |
971 | ||
972 | @item C-Mouse-3 | |
973 | Jump to here. | |
974 | @end table | |
975 | ||
976 | If the variable @code{gdb-find-source-frame} is non-@code{nil} and | |
977 | execution stops in a frame for which there is no source code e.g after | |
978 | an interrupt, then Emacs finds and displays the first frame further up | |
979 | stack for which there is source. If it is @code{nil} then the source | |
980 | buffer continues to display the last frame which maybe more useful, | |
981 | for example, when re-setting a breakpoint. | |
982 | ||
983 | @node Breakpoints Buffer | |
984 | @subsubsection Breakpoints Buffer | |
985 | ||
986 | The breakpoints buffer shows the existing breakpoints, watchpoints and | |
987 | catchpoints (@pxref{Breakpoints,,, gdb, The GNU debugger}). It has | |
988 | these special commands, which mostly apply to the @dfn{current | |
989 | breakpoint}, the breakpoint which point is on. | |
990 | ||
991 | @table @kbd | |
992 | @item @key{SPC} | |
993 | @kindex SPC @r{(GDB breakpoints buffer)} | |
994 | @findex gdb-toggle-breakpoint | |
ae742cb5 | 995 | Enable/disable current breakpoint (@code{gdb-toggle-breakpoint}). |
8cf51b2c GM |
996 | On a graphical display, this changes the color of a bullet in the |
997 | margin of a source buffer at the relevant line. This is red when | |
998 | the breakpoint is enabled and grey when it is disabled. Text-only | |
999 | terminals correspondingly display a @samp{B} or @samp{b}. | |
1000 | ||
1001 | @item D | |
1002 | @kindex D @r{(GDB breakpoints buffer)} | |
1003 | @findex gdb-delete-breakpoint | |
1004 | Delete the current breakpoint (@code{gdb-delete-breakpoint}). | |
1005 | ||
1006 | @item @key{RET} | |
1007 | @kindex RET @r{(GDB breakpoints buffer)} | |
1008 | @findex gdb-goto-breakpoint | |
1009 | Visit the source line for the current breakpoint | |
1010 | (@code{gdb-goto-breakpoint}). | |
1011 | ||
1012 | @item Mouse-2 | |
1013 | @kindex Mouse-2 @r{(GDB breakpoints buffer)} | |
1014 | Visit the source line for the breakpoint you click on. | |
1015 | @end table | |
1016 | ||
691cf4a0 | 1017 | @vindex gdb-show-threads-by-default |
95dbaaea NR |
1018 | When @code{gdb-many-windows} is non-@code{nil}, the breakpoints buffer |
1019 | shares its window with the threads buffer. To switch from one to the | |
8d6bb99e | 1020 | other click with @kbd{Mouse-1} on the relevant button in the header |
691cf4a0 NR |
1021 | line. If @code{gdb-show-threads-by-default} is non-@code{nil}, the |
1022 | threads buffer, rather than the breakpoints buffer, is shown at start | |
1023 | up. | |
1024 | ||
1025 | @node Threads Buffer | |
1026 | @subsubsection Threads Buffer | |
1027 | ||
1028 | @findex gdb-select-thread | |
1029 | The threads buffer displays a summary of all threads currently in your | |
1030 | program (@pxref{Threads, Threads, Debugging programs with multiple | |
1031 | threads, gdb, The GNU debugger}). Move point to any thread in the list | |
1032 | and press @key{RET} to select it (@code{gdb-select-thread}) and | |
1033 | display the associated source in the primary source buffer. | |
1034 | Alternatively, click @kbd{Mouse-2} on a thread to select it. Contents | |
1035 | of all GDB buffers are updated whenever you select a thread. | |
1036 | ||
1037 | You can customize variables under @code{gdb-buffers} group to select | |
1038 | fields included in threads buffer. | |
1039 | ||
1040 | @table @code | |
1041 | @item gdb-thread-buffer-verbose-names | |
1042 | @vindex gdb-thread-buffer-verbose-names | |
1043 | Show long thread names like @samp{Thread 0x4e2ab70 (LWP 1983)} in | |
1044 | threads buffer. | |
1045 | ||
1046 | @item gdb-thread-buffer-arguments | |
1047 | @vindex gdb-thread-buffer-arguments | |
1048 | Show arguments of thread top frames in threads buffer. | |
1049 | ||
1050 | @item gdb-thread-buffer-locations | |
1051 | @vindex gdb-thread-buffer-locations | |
1052 | Show file information or library names in threads buffer. | |
1053 | ||
1054 | @item gdb-thread-buffer-addresses | |
1055 | @vindex gdb-thread-buffer-addresses | |
1056 | Show addresses for thread frames in threads buffer. | |
1057 | @end table | |
1058 | ||
62d94509 | 1059 | It's possible to observe information for several threads |
691cf4a0 NR |
1060 | simultaneously (in addition to buffers which show information for |
1061 | currently selected thread) using the following keys from the threads | |
1062 | buffer. | |
1063 | ||
1064 | @table @kbd | |
1065 | @item d | |
1066 | @kindex d @r{(GDB threads buffer)} | |
1067 | @findex gdb-display-disassembly-for-thread | |
1068 | Display disassembly buffer for the thread at current line. | |
1069 | (@code{gdb-display-disassembly-for-thread}) | |
1070 | ||
1071 | @item f | |
1072 | @kindex f @r{(GDB threads buffer)} | |
1073 | @findex gdb-display-stack-for-thread | |
1074 | Display stack buffer for the thread at current line. | |
1075 | (@code{gdb-display-stack-for-thread}). | |
1076 | ||
1077 | @item l | |
1078 | @kindex l @r{(GDB threads buffer)} | |
1079 | @findex gdb-display-locals-for-thread | |
1080 | Display locals buffer for the thread at current line. | |
1081 | (@code{gdb-display-locals-for-thread}). | |
1082 | ||
1083 | @item r | |
1084 | @kindex r @r{(GDB threads buffer)} | |
1085 | @findex gdb-display-registers-for-thread | |
1086 | Display registers buffer for the thread at current line. | |
1087 | (@code{gdb-display-registers-for-thread}). | |
1088 | @end table | |
1089 | ||
1090 | Pressing their upper-case counterparts, @kbd{D}, @kbd{F} ,@kbd{L} and | |
1091 | @kbd{R} displays the corresponding buffer in a new frame. | |
1092 | ||
1093 | When you create a buffer showing information about some specific | |
1094 | thread, it becomes bound to that thread and keeps showing actual | |
1095 | information while you debug your program. Every GDB buffer contains a | |
1096 | number of thread it shows information for in its mode name. Thread | |
1097 | number is also included in the buffer name of bound buffers to prevent | |
1098 | buffer names clashing. | |
1099 | ||
1100 | Further commands are available in the threads buffer which depend on the | |
1101 | mode of GDB that is used for controlling execution of your program. | |
1102 | (@pxref{Multithreaded Debugging, Stopping and Starting Multi-threaded Programs}). | |
95dbaaea | 1103 | |
8cf51b2c GM |
1104 | @node Stack Buffer |
1105 | @subsubsection Stack Buffer | |
1106 | ||
1107 | The stack buffer displays a @dfn{call stack}, with one line for each | |
1108 | of the nested subroutine calls (@dfn{stack frames}) now active in the | |
1109 | program. @xref{Backtrace,, Backtraces, gdb, The GNU debugger}. | |
1110 | ||
1111 | @findex gdb-frames-select | |
1112 | An arrow in the fringe points to the selected frame or, if the fringe is | |
1113 | not present, the number of the selected frame is displayed in reverse | |
1114 | contrast. To select a frame in GDB, move point in the stack buffer to | |
1115 | that stack frame and type @key{RET} (@code{gdb-frames-select}), or click | |
1116 | @kbd{Mouse-2} on a stack frame. If the locals buffer is visible, | |
1117 | selecting a stack frame updates it to display the local variables of the | |
1118 | new frame. | |
1119 | ||
691cf4a0 | 1120 | @node Other GDB Buffers |
8cf51b2c GM |
1121 | @subsubsection Other Buffers |
1122 | ||
1123 | @table @asis | |
1124 | @item Input/Output Buffer | |
1125 | @vindex gdb-use-separate-io-buffer | |
1126 | If the variable @code{gdb-use-separate-io-buffer} is non-@code{nil}, | |
1127 | the program being debugged takes its input and displays its output | |
1128 | here. Otherwise it uses the GUD buffer for that. To toggle whether | |
1129 | GUD mode uses this buffer, do @kbd{M-x gdb-use-separate-io-buffer}. | |
1130 | This takes effect when you next restart the program you are debugging. | |
1131 | ||
1132 | The history and replay commands from Shell mode are available here, | |
1133 | as are the commands to send signals to the debugged program. | |
1134 | @xref{Shell Mode}. | |
1135 | ||
1136 | @item Locals Buffer | |
1137 | The locals buffer displays the values of local variables of the | |
1138 | current frame for simple data types (@pxref{Frame Info, Frame Info, | |
0df6175c | 1139 | Information on a frame, gdb, The GNU debugger}). Press @key{RET} or |
8cf51b2c GM |
1140 | click @kbd{Mouse-2} on the value if you want to edit it. |
1141 | ||
1142 | Arrays and structures display their type only. With GDB 6.4 or later, | |
1143 | move point to their name and press @key{RET}, or alternatively click | |
1144 | @kbd{Mouse-2} there, to examine their values. With earlier versions | |
1145 | of GDB, use @kbd{Mouse-2} or @key{RET} on the type description | |
1146 | (@samp{[struct/union]} or @samp{[array]}). @xref{Watch Expressions}. | |
1147 | ||
1148 | @item Registers Buffer | |
1149 | @findex toggle-gdb-all-registers | |
1150 | The registers buffer displays the values held by the registers | |
1151 | (@pxref{Registers,,, gdb, The GNU debugger}). Press @key{RET} or | |
1152 | click @kbd{Mouse-2} on a register if you want to edit its value. | |
1153 | With GDB 6.4 or later, recently changed register values display with | |
1154 | @code{font-lock-warning-face}. With earlier versions of GDB, you can | |
1155 | press @key{SPC} to toggle the display of floating point registers | |
1156 | (@code{toggle-gdb-all-registers}). | |
1157 | ||
0df6175c CY |
1158 | @item Assembler Buffer |
1159 | The assembler buffer displays the current frame as machine code. An | |
8cf51b2c GM |
1160 | arrow points to the current instruction, and you can set and remove |
1161 | breakpoints as in a source buffer. Breakpoint icons also appear in | |
1162 | the fringe or margin. | |
1163 | ||
8cf51b2c GM |
1164 | @item Memory Buffer |
1165 | The memory buffer lets you examine sections of program memory | |
1166 | (@pxref{Memory, Memory, Examining memory, gdb, The GNU debugger}). | |
1167 | Click @kbd{Mouse-1} on the appropriate part of the header line to | |
1168 | change the starting address or number of data items that the buffer | |
4a3a621f NR |
1169 | displays. Alternatively, use @kbd{S} or @kbd{N} respectively. Click |
1170 | @kbd{Mouse-3} on the header line to select the display format or unit | |
1171 | size for these data items. | |
8cf51b2c GM |
1172 | @end table |
1173 | ||
691cf4a0 NR |
1174 | When @code{gdb-many-windows} is non-@code{nil}, the locals buffer |
1175 | shares its window with the registers buffer, just like breakpoints | |
1176 | and threads buffers. To switch from one to the other click with | |
0df6175c | 1177 | @kbd{Mouse-1} on the relevant button in the header line. |
1a19cb6a | 1178 | |
8cf51b2c GM |
1179 | @node Watch Expressions |
1180 | @subsubsection Watch Expressions | |
1181 | @cindex Watching expressions in GDB | |
1182 | ||
1183 | @findex gud-watch | |
1184 | @kindex C-x C-a C-w @r{(GUD)} | |
1185 | If you want to see how a variable changes each time your program | |
1186 | stops, move point into the variable name and click on the watch icon | |
1187 | in the tool bar (@code{gud-watch}) or type @kbd{C-x C-a C-w}. If you | |
1188 | specify a prefix argument, you can enter the variable name in the | |
1189 | minibuffer. | |
1190 | ||
1191 | Each watch expression is displayed in the speedbar. Complex data | |
1192 | types, such as arrays, structures and unions are represented in a tree | |
1193 | format. Leaves and simple data types show the name of the expression | |
1194 | and its value and, when the speedbar frame is selected, display the | |
1195 | type as a tooltip. Higher levels show the name, type and address | |
1196 | value for pointers and just the name and type otherwise. Root expressions | |
1197 | also display the frame address as a tooltip to help identify the frame | |
1198 | in which they were defined. | |
1199 | ||
1200 | To expand or contract a complex data type, click @kbd{Mouse-2} or | |
1201 | press @key{SPC} on the tag to the left of the expression. Emacs asks | |
1202 | for confirmation before expanding the expression if its number of | |
1203 | immediate children exceeds the value of the variable | |
1204 | @code{gdb-max-children}. | |
1205 | ||
1206 | @kindex D @r{(GDB speedbar)} | |
1207 | @findex gdb-var-delete | |
1208 | To delete a complex watch expression, move point to the root | |
1209 | expression in the speedbar and type @kbd{D} (@code{gdb-var-delete}). | |
1210 | ||
1211 | @kindex RET @r{(GDB speedbar)} | |
1212 | @findex gdb-edit-value | |
1213 | To edit a variable with a simple data type, or a simple element of a | |
1214 | complex data type, move point there in the speedbar and type @key{RET} | |
1215 | (@code{gdb-edit-value}). Or you can click @kbd{Mouse-2} on a value to | |
1216 | edit it. Either way, this reads the new value using the minibuffer. | |
1217 | ||
1218 | @vindex gdb-show-changed-values | |
1219 | If you set the variable @code{gdb-show-changed-values} to | |
1220 | non-@code{nil} (the default value), Emacs uses | |
1221 | @code{font-lock-warning-face} to highlight values that have recently | |
1222 | changed and @code{shadow} face to make variables which have gone out of | |
1223 | scope less noticeable. When a variable goes out of scope you can't | |
1224 | edit its value. | |
1225 | ||
975900f9 | 1226 | @vindex gdb-delete-out-of-scope |
32ef39ff NR |
1227 | If the variable @code{gdb-delete-out-of-scope} is non-@code{nil} |
1228 | (the default value), Emacs automatically deletes watch expressions | |
1229 | which go out of scope. Sometimes, when re-entering the same function, | |
de933755 CY |
1230 | it may be useful to set this value to @code{nil} so that you don't |
1231 | need to recreate the watch expression. | |
975900f9 | 1232 | |
8cf51b2c GM |
1233 | @vindex gdb-use-colon-colon-notation |
1234 | If the variable @code{gdb-use-colon-colon-notation} is | |
1235 | non-@code{nil}, Emacs uses the @samp{@var{function}::@var{variable}} | |
1236 | format. This allows the user to display watch expressions which share | |
1237 | the same variable name. The default value is @code{nil}. | |
1238 | ||
1239 | @vindex gdb-speedbar-auto-raise | |
1240 | To automatically raise the speedbar every time the display of watch | |
1241 | expressions updates, set @code{gdb-speedbar-auto-raise} to | |
1242 | non-@code{nil}. This can be useful if you are debugging with a full | |
1243 | screen Emacs frame. | |
1244 | ||
691cf4a0 NR |
1245 | @node Multithreaded Debugging |
1246 | @subsubsection Stopping and Starting Multi-threaded Programs | |
1247 | @cindex Multithreaded debugging in GDB | |
1248 | ||
1249 | @subsubheading All-stop Debugging | |
1250 | ||
1251 | In all-stop mode, whenever your program stops, @emph{all} threads of | |
1252 | execution stop. Likewise, whenever you restart the program, all | |
1253 | threads start executing. @xref{All-Stop Mode, , All-Stop Mode, gdb, | |
1254 | The GNU debugger}. You can enable this behaviour in Emacs by setting | |
1255 | @code{gdb-non-stop-setting} to @code{nil} before starting a debugging | |
1256 | session. | |
1257 | ||
1258 | @subsubheading Non-stop Debugging | |
1259 | @cindex Non-stop debugging in GDB | |
1260 | ||
1261 | For some multi-threaded targets, GDB supports a further mode of | |
1262 | operation in which you can examine stopped program threads in the | |
1263 | debugger while other threads continue to execute freely. | |
1264 | @xref{Non-Stop Mode, , Non-Stop Mode, gdb, The GNU debugger}. | |
1265 | This is referred to as @dfn{non-stop} mode. | |
1266 | ||
1267 | Versions of GDB prior to 7.0 do not support non-stop mode and it does | |
1268 | not work on all targets. In such cases, Emacs uses all-stop mode | |
1269 | regardless of the value of @code{gdb-non-stop-setting}. | |
1270 | ||
1271 | @vindex gdb-non-stop-setting | |
1272 | If the variable @code{gdb-non-stop-setting} is non-@code{nil} (the | |
1273 | default value), Emacs tries to start GDB in non-stop mode. Note that | |
1274 | GDB debugging session needs to be restarted for change of this setting | |
1275 | to take effect. | |
1276 | ||
1277 | @vindex gdb-switch-when-another-stopped | |
1278 | When a thread stops in non-stop mode, Emacs automatically switches to | |
1279 | that thread. It may be undesirable to allow switching of current | |
1280 | thread when some other stopped thread is already selected. Set | |
1281 | @code{gdb-switch-when-another-stopped} to @code{nil} to prevent this. | |
1282 | ||
1283 | @vindex gdb-switch-reasons | |
1284 | Emacs can decide whether or not to switch to the stopped thread | |
1285 | depending on the reason which caused the stop. Customize | |
1286 | @code{gdb-switch-reasons} to select stop reasons which make Emacs | |
1287 | switch thread. | |
1288 | ||
1289 | @vindex gdb-stopped-hooks | |
1290 | The variable @code{gdb-stopped-hooks} allows you to execute your | |
1291 | functions whenever some thread stops. | |
1292 | ||
1293 | In non-stop mode, you can switch between different modes for GUD | |
1294 | execution control commands. | |
1295 | ||
1296 | @vindex gdb-gud-control-all-threads | |
1297 | @table @dfn | |
1298 | @item Non-stop/A | |
1299 | ||
1300 | When @code{gdb-gud-control-all-threads} is @code{t} (the default | |
1301 | value), interruption and continuation commands apply to all threads, | |
1302 | so you can halt or continue all your threads with one command using | |
1303 | @code{gud-stop-subjob} and @code{gud-cont}, respectively. The | |
1304 | @samp{Go} button is shown on the toolbar when at least one thread is | |
1305 | stopped, whereas @samp{Stop} button is shown when at least one thread | |
1306 | is running. | |
1307 | ||
1308 | @item Non-stop/T | |
1309 | ||
1310 | When @code{gdb-gud-control-all-threads} is @code{nil}, only the | |
1311 | current thread is stopped/continued. @samp{Go} and @samp{Stop} | |
1312 | buttons on the GUD toolbar are shown depending on the state of current | |
1313 | thread. | |
1314 | @end table | |
1315 | ||
1316 | You can change the current value of @code{gdb-gud-control-all-threads} | |
1317 | from the tool bar or from @samp{GUD->GDB-MI} menu. | |
1318 | ||
1319 | Stepping commands always apply to the current thread. | |
1320 | ||
1321 | @subsubheading Fine Thread Control | |
1322 | ||
1323 | In non-stop mode, you can interrupt/continue your threads without | |
1324 | selecting them. Hitting @kbd{i} in threads buffer interrupts thread | |
1325 | under point, @kbd{c} continues it, @kbd{s} steps through. More such | |
1326 | commands may be added in the future. | |
1327 | ||
1328 | Combined with creating bound buffers for any thread, this allows you | |
1329 | to change and track state of many threads in the same time. | |
1330 | ||
1331 | Note that when you interrupt a thread, it stops with @samp{signal | |
1332 | received} reason. If that reason is included in your | |
1333 | @code{gdb-switch-reasons} (it is by default), Emacs will switch to | |
1334 | that thread. | |
8d6bb99e | 1335 | |
8cf51b2c GM |
1336 | @node Executing Lisp |
1337 | @section Executing Lisp Expressions | |
1338 | ||
1339 | Emacs has several different major modes for Lisp and Scheme. They are | |
1340 | the same in terms of editing commands, but differ in the commands for | |
1341 | executing Lisp expressions. Each mode has its own purpose. | |
1342 | ||
1343 | @table @asis | |
1344 | @item Emacs-Lisp mode | |
1345 | The mode for editing source files of programs to run in Emacs Lisp. | |
1346 | This mode defines @kbd{C-M-x} to evaluate the current defun. | |
1347 | @xref{Lisp Libraries}. | |
1348 | @item Lisp Interaction mode | |
1349 | The mode for an interactive session with Emacs Lisp. It defines | |
1350 | @kbd{C-j} to evaluate the sexp before point and insert its value in the | |
1351 | buffer. @xref{Lisp Interaction}. | |
1352 | @item Lisp mode | |
1353 | The mode for editing source files of programs that run in Lisps other | |
1354 | than Emacs Lisp. This mode defines @kbd{C-M-x} to send the current defun | |
1355 | to an inferior Lisp process. @xref{External Lisp}. | |
1356 | @item Inferior Lisp mode | |
1357 | The mode for an interactive session with an inferior Lisp process. | |
1358 | This mode combines the special features of Lisp mode and Shell mode | |
1359 | (@pxref{Shell Mode}). | |
1360 | @item Scheme mode | |
1361 | Like Lisp mode but for Scheme programs. | |
1362 | @item Inferior Scheme mode | |
1363 | The mode for an interactive session with an inferior Scheme process. | |
1364 | @end table | |
1365 | ||
1366 | Most editing commands for working with Lisp programs are in fact | |
1367 | available globally. @xref{Programs}. | |
1368 | ||
1369 | @node Lisp Libraries | |
1370 | @section Libraries of Lisp Code for Emacs | |
1371 | @cindex libraries | |
1372 | @cindex loading Lisp code | |
1373 | ||
1374 | Lisp code for Emacs editing commands is stored in files whose names | |
1375 | conventionally end in @file{.el}. This ending tells Emacs to edit them in | |
1376 | Emacs-Lisp mode (@pxref{Executing Lisp}). | |
1377 | ||
1378 | @cindex byte code | |
1379 | Emacs Lisp code can be compiled into byte-code, which loads faster, | |
1380 | takes up less space, and executes faster. @xref{Byte Compilation,, | |
1381 | Byte Compilation, elisp, the Emacs Lisp Reference Manual}. By | |
1382 | convention, the compiled code for a library goes in a separate file | |
1383 | whose name ends in @samp{.elc}. Thus, the compiled code for | |
1384 | @file{foo.el} goes in @file{foo.elc}. | |
1385 | ||
1386 | @findex load-file | |
1387 | To execute a file of Emacs Lisp code, use @kbd{M-x load-file}. This | |
1388 | command reads a file name using the minibuffer and then executes the | |
1389 | contents of that file as Lisp code. It is not necessary to visit the | |
1390 | file first; in any case, this command reads the file as found on disk, | |
1391 | not text in an Emacs buffer. | |
1392 | ||
1393 | @findex load | |
1394 | @findex load-library | |
1395 | Once a file of Lisp code is installed in the Emacs Lisp library | |
1396 | directories, users can load it using @kbd{M-x load-library}. Programs | |
1397 | can load it by calling @code{load}, a more primitive function that is | |
1398 | similar but accepts some additional arguments. | |
1399 | ||
1400 | @kbd{M-x load-library} differs from @kbd{M-x load-file} in that it | |
1401 | searches a sequence of directories and tries three file names in each | |
1402 | directory. Suppose your argument is @var{lib}; the three names are | |
1403 | @file{@var{lib}.elc}, @file{@var{lib}.el}, and lastly just | |
1404 | @file{@var{lib}}. If @file{@var{lib}.elc} exists, it is by convention | |
1405 | the result of compiling @file{@var{lib}.el}; it is better to load the | |
1406 | compiled file, since it will load and run faster. | |
1407 | ||
1408 | If @code{load-library} finds that @file{@var{lib}.el} is newer than | |
1409 | @file{@var{lib}.elc} file, it issues a warning, because it's likely | |
1410 | that somebody made changes to the @file{.el} file and forgot to | |
1411 | recompile it. Nonetheless, it loads @file{@var{lib}.elc}. This is | |
1412 | because people often leave unfinished edits the source file, and don't | |
1413 | recompile it until they think it is ready to use. | |
1414 | ||
8cf51b2c | 1415 | @vindex load-path |
1557ef4f CY |
1416 | The variable @code{load-path} specifies the sequence of directories |
1417 | searched by @kbd{M-x load-library}. Its value should be a list of | |
f3ed4f26 CY |
1418 | strings that are directory names; in addition, @code{nil} in this list |
1419 | stands for the current default directory. (Generally, it is not a | |
1420 | good idea to put @code{nil} in the list; if you find yourself wishing | |
1421 | that @code{nil} were in the list, most likely what you really want is | |
1422 | to do @kbd{M-x load-file} this once.) | |
1557ef4f CY |
1423 | |
1424 | The default value of @code{load-path} is a list of directories where | |
8cf51b2c | 1425 | the Lisp code for Emacs itself is stored. If you have libraries of |
1557ef4f CY |
1426 | your own, put them in a single directory and add that directory to |
1427 | @code{load-path}, by adding a line like this to your init file | |
1428 | (@pxref{Init File}): | |
1429 | ||
1430 | @example | |
1431 | (add-to-list 'load-path "/path/to/lisp/libraries") | |
1432 | @end example | |
8cf51b2c GM |
1433 | |
1434 | @cindex autoload | |
e8d2d3fb CY |
1435 | Some commands are @dfn{autoloaded}: when you run them, Emacs will |
1436 | automatically load the associated library first. For instance, the | |
1437 | @code{compile} and @code{compilation-mode} commands | |
1438 | (@pxref{Compilation}) are autoloaded; if you call either command, | |
1439 | Emacs automatically loads the @code{compile} library. In contrast, | |
1440 | the command @code{recompile} is not autoloaded, so it is unavailable | |
1441 | until you load the @code{compile} library. | |
8cf51b2c GM |
1442 | |
1443 | @vindex load-dangerous-libraries | |
1444 | @cindex Lisp files byte-compiled by XEmacs | |
1445 | By default, Emacs refuses to load compiled Lisp files which were | |
1446 | compiled with XEmacs, a modified versions of Emacs---they can cause | |
1447 | Emacs to crash. Set the variable @code{load-dangerous-libraries} to | |
1448 | @code{t} if you want to try loading them. | |
1449 | ||
1450 | @node Lisp Eval | |
1451 | @section Evaluating Emacs Lisp Expressions | |
1452 | @cindex Emacs-Lisp mode | |
1453 | @cindex mode, Emacs-Lisp | |
1454 | ||
1455 | @findex emacs-lisp-mode | |
1456 | Lisp programs intended to be run in Emacs should be edited in | |
1457 | Emacs-Lisp mode; this happens automatically for file names ending in | |
1458 | @file{.el}. By contrast, Lisp mode itself is used for editing Lisp | |
1459 | programs intended for other Lisp systems. To switch to Emacs-Lisp mode | |
1460 | explicitly, use the command @kbd{M-x emacs-lisp-mode}. | |
1461 | ||
1462 | For testing of Lisp programs to run in Emacs, it is often useful to | |
1463 | evaluate part of the program as it is found in the Emacs buffer. For | |
1464 | example, after changing the text of a Lisp function definition, | |
1465 | evaluating the definition installs the change for future calls to the | |
1466 | function. Evaluation of Lisp expressions is also useful in any kind of | |
1467 | editing, for invoking noninteractive functions (functions that are | |
1468 | not commands). | |
1469 | ||
1470 | @table @kbd | |
1471 | @item M-: | |
1472 | Read a single Lisp expression in the minibuffer, evaluate it, and print | |
1473 | the value in the echo area (@code{eval-expression}). | |
1474 | @item C-x C-e | |
1475 | Evaluate the Lisp expression before point, and print the value in the | |
1476 | echo area (@code{eval-last-sexp}). | |
1477 | @item C-M-x | |
1478 | Evaluate the defun containing or after point, and print the value in | |
1479 | the echo area (@code{eval-defun}). | |
1480 | @item M-x eval-region | |
1481 | Evaluate all the Lisp expressions in the region. | |
1482 | @item M-x eval-buffer | |
1483 | Evaluate all the Lisp expressions in the buffer. | |
1484 | @end table | |
1485 | ||
1486 | @ifinfo | |
1487 | @c This uses ``colon'' instead of a literal `:' because Info cannot | |
1488 | @c cope with a `:' in a menu | |
1489 | @kindex M-@key{colon} | |
1490 | @end ifinfo | |
1491 | @ifnotinfo | |
1492 | @kindex M-: | |
1493 | @end ifnotinfo | |
1494 | @findex eval-expression | |
1495 | @kbd{M-:} (@code{eval-expression}) is the most basic command for evaluating | |
1496 | a Lisp expression interactively. It reads the expression using the | |
1497 | minibuffer, so you can execute any expression on a buffer regardless of | |
1498 | what the buffer contains. When the expression is evaluated, the current | |
1499 | buffer is once again the buffer that was current when @kbd{M-:} was | |
1500 | typed. | |
1501 | ||
1502 | @kindex C-M-x @r{(Emacs-Lisp mode)} | |
1503 | @findex eval-defun | |
1504 | In Emacs-Lisp mode, the key @kbd{C-M-x} is bound to the command | |
1505 | @code{eval-defun}, which parses the defun containing or following point | |
1506 | as a Lisp expression and evaluates it. The value is printed in the echo | |
1507 | area. This command is convenient for installing in the Lisp environment | |
1508 | changes that you have just made in the text of a function definition. | |
1509 | ||
1510 | @kbd{C-M-x} treats @code{defvar} expressions specially. Normally, | |
1511 | evaluating a @code{defvar} expression does nothing if the variable it | |
1512 | defines already has a value. But @kbd{C-M-x} unconditionally resets the | |
1513 | variable to the initial value specified in the @code{defvar} expression. | |
1514 | @code{defcustom} expressions are treated similarly. | |
1515 | This special feature is convenient for debugging Lisp programs. | |
1516 | Typing @kbd{C-M-x} on a @code{defface} expression reinitializes | |
1517 | the face according to the @code{defface} specification. | |
1518 | ||
1519 | @kindex C-x C-e | |
1520 | @findex eval-last-sexp | |
1521 | The command @kbd{C-x C-e} (@code{eval-last-sexp}) evaluates the Lisp | |
1522 | expression preceding point in the buffer, and displays the value in the | |
1523 | echo area. It is available in all major modes, not just Emacs-Lisp | |
1524 | mode. It does not treat @code{defvar} specially. | |
1525 | ||
1526 | When the result of an evaluation is an integer, you can type | |
1527 | @kbd{C-x C-e} a second time to display the value of the integer result | |
1528 | in additional formats (octal, hexadecimal, and character). | |
1529 | ||
1530 | If @kbd{C-x C-e}, or @kbd{M-:} is given a numeric argument, it | |
1531 | inserts the value into the current buffer at point, rather than | |
1532 | displaying it in the echo area. The argument's value does not matter. | |
1533 | @kbd{C-M-x} with a numeric argument instruments the function | |
1534 | definition for Edebug (@pxref{Instrumenting, Instrumenting for Edebug,, elisp, the Emacs Lisp Reference Manual}). | |
1535 | ||
1536 | @findex eval-region | |
1537 | @findex eval-buffer | |
1538 | The most general command for evaluating Lisp expressions from a buffer | |
1539 | is @code{eval-region}. @kbd{M-x eval-region} parses the text of the | |
1540 | region as one or more Lisp expressions, evaluating them one by one. | |
1541 | @kbd{M-x eval-buffer} is similar but evaluates the entire | |
1542 | buffer. This is a reasonable way to install the contents of a file of | |
1543 | Lisp code that you are ready to test. Later, as you find bugs and | |
1544 | change individual functions, use @kbd{C-M-x} on each function that you | |
1545 | change. This keeps the Lisp world in step with the source file. | |
1546 | ||
1547 | @vindex eval-expression-print-level | |
1548 | @vindex eval-expression-print-length | |
1549 | @vindex eval-expression-debug-on-error | |
1550 | The two customizable variables @code{eval-expression-print-level} and | |
1551 | @code{eval-expression-print-length} control the maximum depth and length | |
1552 | of lists to print in the result of the evaluation commands before | |
1553 | abbreviating them. @code{eval-expression-debug-on-error} controls | |
1554 | whether evaluation errors invoke the debugger when these commands are | |
1555 | used; its default is @code{t}. | |
1556 | ||
1557 | @node Lisp Interaction | |
1558 | @section Lisp Interaction Buffers | |
1559 | ||
a03334ca CY |
1560 | When Emacs starts up, it contains a buffer named @samp{*scratch*}, |
1561 | which is provided for evaluating Lisp expressions interactively inside | |
1562 | Emacs. Its major mode is Lisp Interaction mode. | |
8cf51b2c | 1563 | |
a03334ca CY |
1564 | @findex eval-print-last-sexp |
1565 | @kindex C-j @r{(Lisp Interaction mode)} | |
1566 | The simplest way to use the @samp{*scratch*} buffer is to insert | |
1567 | Lisp expressions and type @kbd{C-j} (@code{eval-print-last-sexp}) | |
1568 | after each expression. This command reads the Lisp expression before | |
1569 | point, evaluates it, and inserts the value in printed representation | |
1570 | before point. The result is a complete typescript of the expressions | |
1571 | you have evaluated and their values. | |
8cf51b2c | 1572 | |
be77bd45 CY |
1573 | @vindex initial-scratch-message |
1574 | At startup, the @samp{*scratch*} buffer contains a short message, in | |
1575 | the form of a Lisp comment, that explains what it is for. This | |
1576 | message is controlled by the variable @code{initial-scratch-message}, | |
1577 | which should be either a string or @code{nil}. If you set it to the | |
1578 | empty string, or @code{nil}, the initial message is suppressed. | |
1579 | ||
8cf51b2c | 1580 | @findex lisp-interaction-mode |
a03334ca CY |
1581 | All other commands in Lisp Interaction mode are the same as in Emacs |
1582 | Lisp mode. You can enable Lisp Interaction mode by typing @kbd{M-x | |
1583 | lisp-interaction-mode}. | |
8cf51b2c GM |
1584 | |
1585 | @findex ielm | |
1586 | An alternative way of evaluating Emacs Lisp expressions interactively | |
1587 | is to use Inferior Emacs-Lisp mode, which provides an interface rather | |
1588 | like Shell mode (@pxref{Shell Mode}) for evaluating Emacs Lisp | |
1589 | expressions. Type @kbd{M-x ielm} to create an @samp{*ielm*} buffer | |
1590 | which uses this mode. For more information see that command's | |
1591 | documentation. | |
1592 | ||
1593 | @node External Lisp | |
1594 | @section Running an External Lisp | |
1595 | ||
1596 | Emacs has facilities for running programs in other Lisp systems. You can | |
1597 | run a Lisp process as an inferior of Emacs, and pass expressions to it to | |
1598 | be evaluated. You can also pass changed function definitions directly from | |
1599 | the Emacs buffers in which you edit the Lisp programs to the inferior Lisp | |
1600 | process. | |
1601 | ||
1602 | @findex run-lisp | |
1603 | @vindex inferior-lisp-program | |
1604 | @kindex C-x C-z | |
1605 | To run an inferior Lisp process, type @kbd{M-x run-lisp}. This runs | |
1606 | the program named @code{lisp}, the same program you would run by typing | |
1607 | @code{lisp} as a shell command, with both input and output going through | |
1608 | an Emacs buffer named @samp{*lisp*}. That is to say, any ``terminal | |
1609 | output'' from Lisp will go into the buffer, advancing point, and any | |
1610 | ``terminal input'' for Lisp comes from text in the buffer. (You can | |
1611 | change the name of the Lisp executable file by setting the variable | |
1612 | @code{inferior-lisp-program}.) | |
1613 | ||
1614 | To give input to Lisp, go to the end of the buffer and type the input, | |
1615 | terminated by @key{RET}. The @samp{*lisp*} buffer is in Inferior Lisp | |
1616 | mode, which combines the special characteristics of Lisp mode with most | |
1617 | of the features of Shell mode (@pxref{Shell Mode}). The definition of | |
1618 | @key{RET} to send a line to a subprocess is one of the features of Shell | |
1619 | mode. | |
1620 | ||
1621 | @findex lisp-mode | |
1622 | For the source files of programs to run in external Lisps, use Lisp | |
1623 | mode. You can switch to this mode with @kbd{M-x lisp-mode}, and it is | |
1624 | used automatically for files whose names end in @file{.l}, | |
1625 | @file{.lsp}, or @file{.lisp}. | |
1626 | ||
1627 | @kindex C-M-x @r{(Lisp mode)} | |
1628 | @findex lisp-eval-defun | |
1629 | When you edit a function in a Lisp program you are running, the easiest | |
1630 | way to send the changed definition to the inferior Lisp process is the key | |
1631 | @kbd{C-M-x}. In Lisp mode, this runs the function @code{lisp-eval-defun}, | |
1632 | which finds the defun around or following point and sends it as input to | |
1633 | the Lisp process. (Emacs can send input to any inferior process regardless | |
1634 | of what buffer is current.) | |
1635 | ||
1636 | Contrast the meanings of @kbd{C-M-x} in Lisp mode (for editing | |
1637 | programs to be run in another Lisp system) and Emacs-Lisp mode (for | |
1638 | editing Lisp programs to be run in Emacs; see @pxref{Lisp Eval}): in | |
1639 | both modes it has the effect of installing the function definition | |
1640 | that point is in, but the way of doing so is different according to | |
1641 | where the relevant Lisp environment is found. |