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6bf7aab6 | 1 | @c This is part of the Emacs manual. |
b65d8176 | 2 | @c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001, |
8d99e09d | 3 | @c 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc. |
6bf7aab6 | 4 | @c See file emacs.texi for copying conditions. |
ffb1af2b | 5 | @node Building, Maintaining, Programs, Top |
6bf7aab6 DL |
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 | |
a6f0d581 | 13 | in the larger process of compiling and testing programs. |
6bf7aab6 DL |
14 | |
15 | @menu | |
16 | * Compilation:: Compiling programs in languages other | |
17 | than Lisp (C, Pascal, etc.). | |
6bf7aab6 DL |
18 | * Compilation Mode:: The mode for visiting compiler errors. |
19 | * Compilation Shell:: Customizing your shell properly | |
20 | for use in the compilation buffer. | |
ed4389af | 21 | * Grep Searching:: Searching with grep. |
ff994d96 | 22 | * Flymake:: Finding syntax errors on the fly. |
177c0ea7 JB |
23 | * Debuggers:: Running symbolic debuggers for non-Lisp programs. |
24 | * Executing Lisp:: Various modes for editing Lisp programs, | |
6bf7aab6 | 25 | with different facilities for running |
177c0ea7 | 26 | the Lisp programs. |
6bf7aab6 | 27 | * Libraries: Lisp Libraries. Creating Lisp programs to run in Emacs. |
6bf7aab6 | 28 | * Eval: Lisp Eval. Executing a single Lisp expression in Emacs. |
254196f5 | 29 | * Interaction: Lisp Interaction. Executing Lisp in an Emacs buffer. |
177c0ea7 | 30 | * External Lisp:: Communicating through Emacs with a separate Lisp. |
6bf7aab6 DL |
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 | |
74b1aac1 | 47 | Run a compiler asynchronously under Emacs, with error messages going to |
58fa012d | 48 | the @samp{*compilation*} buffer. |
9ee31341 EZ |
49 | @item M-x recompile |
50 | Invoke a compiler with the same command as in the last invocation of | |
51 | @kbd{M-x compile}. | |
6bf7aab6 | 52 | @item M-x kill-compilation |
b00d98ed | 53 | Kill the running compilation subprocess. |
6bf7aab6 DL |
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 | |
7d6596b8 RS |
66 | The default for the compilation command is normally @samp{make -k}, |
67 | which is correct most of the time for nontrivial programs. | |
68 | (@xref{Top,, Make, make, GNU Make Manual}.) If you have done @kbd{M-x | |
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}. | |
6bf7aab6 DL |
76 | |
77 | Starting a compilation displays the buffer @samp{*compilation*} in | |
91f1fd02 RS |
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. | |
6bf7aab6 DL |
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 | ||
41f633c1 | 93 | @cindex compilation buffer, keeping point at end |
6bf7aab6 DL |
94 | @vindex compilation-scroll-output |
95 | If you set the variable @code{compilation-scroll-output} to a | |
96 | non-@code{nil} value, then the compilation buffer always scrolls to | |
97 | follow output as it comes in. | |
98 | ||
9ee31341 EZ |
99 | @findex recompile |
100 | To rerun the last compilation with the same command, type @kbd{M-x | |
3fce19f1 RS |
101 | recompile}. This automatically reuses the compilation command from |
102 | the last invocation of @kbd{M-x compile}. It also reuses the | |
103 | @samp{*compilation*} buffer and starts the compilation in its default | |
104 | directory, which is the directory in which the previous compilation | |
105 | was started. | |
9ee31341 | 106 | |
41f633c1 RS |
107 | When the compiler process terminates, for whatever reason, the mode |
108 | line of the @samp{*compilation*} buffer changes to say @samp{exit} | |
109 | (followed by the exit code, @samp{[0]} for a normal exit), or | |
110 | @samp{signal} (if a signal terminated the process), instead of | |
111 | @samp{run}. | |
112 | ||
113 | @findex kill-compilation | |
444246ca | 114 | Starting a new compilation also kills any compilation already |
41f633c1 RS |
115 | running in @samp{*compilation*}, as the buffer can only handle one |
116 | compilation at any time. However, @kbd{M-x compile} asks for | |
117 | confirmation before actually killing a compilation that is running. | |
118 | You can also kill the compilation process with @kbd{M-x | |
119 | kill-compilation}. | |
120 | ||
121 | If you want to run two compilations at once, you should start the | |
122 | first one, then rename the @samp{*compilation*} buffer (perhaps using | |
123 | @code{rename-uniquely}; @pxref{Misc Buffer}), and start the other | |
124 | compilation. That will create a new @samp{*compilation*} buffer. | |
125 | ||
43b4d3c0 | 126 | Emacs does not expect a compiler process to launch asynchronous |
266e712e | 127 | subprocesses; if it does, and they keep running after the main |
43b4d3c0 RS |
128 | compiler process has terminated, Emacs may kill them or their output |
129 | may not arrive in Emacs. To avoid this problem, make the main process | |
130 | wait for its subprocesses to finish. In a shell script, you can do this | |
131 | using @samp{$!} and @samp{wait}, like this: | |
132 | ||
133 | @example | |
134 | (sleep 10; echo 2nd)& pid=$! # @r{Record pid of subprocess} | |
135 | echo first message | |
136 | wait $pid # @r{Wait for subprocess} | |
137 | @end example | |
266e712e | 138 | |
9cad1898 RS |
139 | If the background process does not output to the compilation buffer, |
140 | so you only need to prevent it from being killed when the main | |
141 | compilation process terminates, this is sufficient: | |
142 | ||
143 | @example | |
144 | nohup @var{command}; sleep 1 | |
145 | @end example | |
146 | ||
147 | @vindex compilation-environment | |
148 | You can control the environment passed to the compilation command | |
149 | with the variable @code{compilation-environment}. Its value is a list | |
150 | of environment variable settings; each element should be a string of | |
151 | the form @code{"@var{envvarname}=@var{value}"}. These environment | |
152 | variable settings override the usual ones. | |
153 | ||
6bf7aab6 DL |
154 | @node Compilation Mode |
155 | @section Compilation Mode | |
156 | ||
6bf7aab6 DL |
157 | @cindex Compilation mode |
158 | @cindex mode, Compilation | |
41f633c1 RS |
159 | The @samp{*compilation*} buffer uses a special major mode, |
160 | Compilation mode, whose main feature is to provide a convenient way to | |
161 | visit the source line corresponding to an error message. These | |
162 | commands are also available in other special buffers that list | |
163 | locations in files, including those made by @kbd{M-x grep} and | |
164 | @kbd{M-x occur}. | |
6bf7aab6 DL |
165 | |
166 | @table @kbd | |
089ed565 KS |
167 | @item M-g M-n |
168 | @itemx M-g n | |
169 | @itemx C-x ` | |
41f633c1 | 170 | Visit the locus of the next error message or match. |
089ed565 KS |
171 | @item M-g M-p |
172 | @itemx M-g p | |
41f633c1 | 173 | Visit the locus of the previous error message or match. |
6bf7aab6 DL |
174 | @item @key{RET} |
175 | Visit the locus of the error message that point is on. | |
176 | This command is used in the compilation buffer. | |
177 | @item Mouse-2 | |
178 | Visit the locus of the error message that you click on. | |
ed4389af RS |
179 | @item M-n |
180 | Find and highlight the locus of the next error message, without | |
181 | selecting the source buffer. | |
182 | @item M-p | |
183 | Find and highlight the locus of the previous error message, without | |
184 | selecting the source buffer. | |
185 | @item M-@} | |
186 | Move point to the next error for a different file than the current | |
187 | one. | |
188 | @item M-@{ | |
189 | Move point to the previous error for a different file than the current | |
190 | one. | |
191 | @item C-c C-f | |
192 | Toggle Next Error Follow minor mode, which makes cursor motion in the | |
193 | compilation buffer produce automatic source display. | |
6bf7aab6 DL |
194 | @end table |
195 | ||
41f633c1 | 196 | @findex compile-goto-error |
6bf7aab6 | 197 | You can visit the source for any particular error message by moving |
58fa012d EZ |
198 | point in the @samp{*compilation*} buffer to that error message and |
199 | typing @key{RET} (@code{compile-goto-error}). Alternatively, you can | |
200 | click @kbd{Mouse-2} on the error message; you need not switch to the | |
201 | @samp{*compilation*} buffer first. | |
6bf7aab6 | 202 | |
41f633c1 RS |
203 | @kindex M-g M-n |
204 | @kindex M-g n | |
205 | @kindex C-x ` | |
206 | @findex next-error | |
ed4389af | 207 | @vindex next-error-highlight |
6bf7aab6 DL |
208 | To parse the compiler error messages sequentially, type @kbd{C-x `} |
209 | (@code{next-error}). The character following the @kbd{C-x} is the | |
210 | backquote or ``grave accent,'' not the single-quote. This command is | |
ed4389af RS |
211 | available in all buffers, not just in @samp{*compilation*}; it |
212 | displays the next error message at the top of one window and source | |
213 | location of the error in another window. It also momentarily | |
214 | highlights the relevant source line. You can change the behavior of | |
215 | this highlighting with the variable @code{next-error-highlight}. | |
6bf7aab6 | 216 | |
41f633c1 RS |
217 | The first time @w{@kbd{C-x `}} is used after the start of a compilation, |
218 | it moves to the first error's location. Subsequent uses of @kbd{C-x | |
219 | `} advance down to subsequent errors. If you visit a specific error | |
220 | message with @key{RET} or @kbd{Mouse-2}, subsequent @w{@kbd{C-x `}} | |
221 | commands advance from there. When @w{@kbd{C-x `}} gets to the end of the | |
6bf7aab6 | 222 | buffer and finds no more error messages to visit, it fails and signals |
41f633c1 RS |
223 | an Emacs error. @w{@kbd{C-u C-x `}} starts scanning from the beginning of |
224 | the compilation buffer, and goes to the first error's location. | |
6bf7aab6 | 225 | |
d938fad2 | 226 | @vindex compilation-skip-threshold |
41f633c1 | 227 | By default, @w{@kbd{C-x `}} skips less important messages. The variable |
d938fad2 | 228 | @code{compilation-skip-threshold} controls this. If its value is 2, |
41f633c1 RS |
229 | @w{@kbd{C-x `}} skips anything less than error, 1 skips anything less |
230 | than warning, and 0 doesn't skip any messages. The default is 1. | |
d938fad2 | 231 | |
41f633c1 RS |
232 | When the window has a left fringe, an arrow in the fringe points to |
233 | the current message in the compilation buffer. The variable | |
cb7b02c7 | 234 | @code{compilation-context-lines} controls the number of lines of |
41f633c1 RS |
235 | leading context to display before the current message. Going to an |
236 | error message location scrolls the @samp{*compilation*} buffer to put | |
237 | the message that far down from the top. The value @code{nil} is | |
238 | special: if there's a left fringe, the window doesn't scroll at all | |
239 | if the message is already visible. If there is no left fringe, | |
240 | @code{nil} means display the message at the top of the window. | |
cb7b02c7 | 241 | |
7d6596b8 RS |
242 | If you're not in the compilation buffer when you run |
243 | @code{next-error}, Emacs will look for a buffer that contains error | |
244 | messages. First, it looks for one displayed in the selected frame, | |
245 | then for one that previously had @code{next-error} called on it, and | |
246 | then at the current buffer. Finally, Emacs looks at all the remaining | |
247 | buffers. @code{next-error} signals an error if it can't find any such | |
248 | buffer. | |
249 | ||
0825052e EZ |
250 | @vindex compilation-error-regexp-alist |
251 | @vindex grep-regexp-alist | |
252 | To parse messages from the compiler, Compilation mode uses the | |
253 | variable @code{compilation-error-regexp-alist} which lists various | |
254 | formats of error messages and tells Emacs how to extract the source file | |
255 | and the line number from the text of a message. If your compiler isn't | |
256 | supported, you can tailor Compilation mode to it by adding elements to | |
257 | that list. A similar variable @code{grep-regexp-alist} tells Emacs how | |
258 | to parse output of a @code{grep} command. | |
259 | ||
ed4389af RS |
260 | @findex compilation-next-error |
261 | @findex compilation-previous-error | |
262 | @findex compilation-next-file | |
263 | @findex compilation-previous-file | |
6bf7aab6 | 264 | Compilation mode also redefines the keys @key{SPC} and @key{DEL} to |
ed4389af RS |
265 | scroll by screenfuls, and @kbd{M-n} (@code{compilation-next-error}) |
266 | and @kbd{M-p} (@code{compilation-previous-error}) to move to the next | |
267 | or previous error message. You can also use @kbd{M-@{} | |
268 | (@code{compilation-next-file} and @kbd{M-@}} | |
269 | (@code{compilation-previous-file}) to move up or down to an error | |
270 | message for a different source file. | |
271 | ||
272 | @cindex Next Error Follow mode | |
273 | @findex next-error-follow-minor-mode | |
274 | You can type @kbd{C-c C-f} to toggle Next Error Follow mode. In | |
275 | this minor mode, ordinary cursor motion in the compilation buffer | |
276 | automatically updates the source buffer. For instance, moving the | |
277 | cursor to the next error message causes the location of that error to | |
278 | be displayed immediately. | |
6bf7aab6 DL |
279 | |
280 | The features of Compilation mode are also available in a minor mode | |
281 | called Compilation Minor mode. This lets you parse error messages in | |
282 | any buffer, not just a normal compilation output buffer. Type @kbd{M-x | |
283 | compilation-minor-mode} to enable the minor mode. This defines the keys | |
284 | @key{RET} and @kbd{Mouse-2}, as in the Compilation major mode. | |
285 | ||
286 | Compilation minor mode works in any buffer, as long as the contents | |
287 | are in a format that it understands. In an Rlogin buffer (@pxref{Remote | |
288 | Host}), Compilation minor mode automatically accesses remote source | |
289 | files by FTP (@pxref{File Names}). | |
290 | ||
291 | @node Compilation Shell | |
292 | @section Subshells for Compilation | |
293 | ||
41f633c1 RS |
294 | Emacs uses a shell to run the compilation command, but specifies the |
295 | option for a noninteractive shell. This means, in particular, that | |
6bf7aab6 DL |
296 | the shell should start with no prompt. If you find your usual shell |
297 | prompt making an unsightly appearance in the @samp{*compilation*} | |
298 | buffer, it means you have made a mistake in your shell's init file by | |
299 | setting the prompt unconditionally. (This init file's name may be | |
41f633c1 RS |
300 | @file{.bashrc}, @file{.profile}, @file{.cshrc}, @file{.shrc}, or |
301 | various other things, depending on the shell you use.) The shell init | |
302 | file should set the prompt only if there already is a prompt. Here's | |
303 | how to do it in bash: | |
6bf7aab6 DL |
304 | |
305 | @example | |
41f633c1 RS |
306 | if [ "$@{PS1+set@}" = set ] |
307 | then PS1=@dots{} | |
308 | fi | |
6bf7aab6 DL |
309 | @end example |
310 | ||
311 | @noindent | |
41f633c1 | 312 | And here's how to do it in csh: |
6bf7aab6 DL |
313 | |
314 | @example | |
41f633c1 | 315 | if ($?prompt) set prompt = @dots{} |
6bf7aab6 DL |
316 | @end example |
317 | ||
318 | There may well be other things that your shell's init file | |
319 | ought to do only for an interactive shell. You can use the same | |
320 | method to conditionalize them. | |
321 | ||
322 | The MS-DOS ``operating system'' does not support asynchronous | |
323 | subprocesses; to work around this lack, @kbd{M-x compile} runs the | |
324 | compilation command synchronously on MS-DOS. As a consequence, you must | |
325 | wait until the command finishes before you can do anything else in | |
eca2d6cd EZ |
326 | Emacs. |
327 | @iftex | |
328 | @inforef{MS-DOS,,emacs-xtra}. | |
329 | @end iftex | |
330 | @ifnottex | |
331 | @xref{MS-DOS}. | |
332 | @end ifnottex | |
6bf7aab6 | 333 | |
ed4389af RS |
334 | @node Grep Searching |
335 | @section Searching with Grep under Emacs | |
336 | ||
ed4389af | 337 | Just as you can run a compiler from Emacs and then visit the lines |
869d986e | 338 | with compilation errors, you can also run @code{grep} and |
ed4389af RS |
339 | then visit the lines on which matches were found. This works by |
340 | treating the matches reported by @code{grep} as if they were ``errors.'' | |
341 | ||
b00d98ed JL |
342 | @table @kbd |
343 | @item M-x grep | |
b5eb27b3 | 344 | @item M-x lgrep |
b00d98ed JL |
345 | Run @code{grep} asynchronously under Emacs, with matching lines |
346 | listed in the buffer named @samp{*grep*}. | |
347 | @item M-x grep-find | |
348 | @itemx M-x find-grep | |
b5eb27b3 | 349 | @itemx M-x rgrep |
b00d98ed JL |
350 | Run @code{grep} via @code{find}, with user-specified arguments, and |
351 | collect output in the buffer named @samp{*grep*}. | |
352 | @item M-x kill-grep | |
353 | Kill the running @code{grep} subprocess. | |
354 | @end table | |
355 | ||
356 | @findex grep | |
41f633c1 RS |
357 | To run @code{grep}, type @kbd{M-x grep}, then enter a command line |
358 | that specifies how to run @code{grep}. Use the same arguments you | |
359 | would give @code{grep} when running it normally: a @code{grep}-style | |
360 | regexp (usually in single-quotes to quote the shell's special | |
361 | characters) followed by file names, which may use wildcards. If you | |
7ae038f0 RS |
362 | specify a prefix argument for @kbd{M-x grep}, it finds the tag |
363 | (@pxref{Tags}) in the buffer around point, and puts that into the | |
364 | default @code{grep} command. | |
365 | ||
366 | Your command need not simply run @code{grep}; you can use any shell | |
367 | command that produces output in the same format. For instance, you | |
368 | can chain @code{grep} commands, like this: | |
369 | ||
370 | @example | |
371 | grep -nH -e foo *.el | grep bar | grep toto | |
372 | @end example | |
ed4389af RS |
373 | |
374 | The output from @code{grep} goes in the @samp{*grep*} buffer. You | |
41f633c1 RS |
375 | can find the corresponding lines in the original files using @w{@kbd{C-x |
376 | `}}, @key{RET}, and so forth, just like compilation errors. | |
ed4389af RS |
377 | |
378 | Some grep programs accept a @samp{--color} option to output special | |
379 | markers around matches for the purpose of highlighting. You can make | |
d81dbd54 JB |
380 | use of this feature by setting @code{grep-highlight-matches} to |
381 | @code{t}. When displaying a match in the source buffer, the exact | |
382 | match will be highlighted, instead of the entire source line. | |
ed4389af RS |
383 | |
384 | @findex grep-find | |
385 | @findex find-grep | |
386 | The command @kbd{M-x grep-find} (also available as @kbd{M-x | |
387 | find-grep}) is similar to @kbd{M-x grep}, but it supplies a different | |
388 | initial default for the command---one that runs both @code{find} and | |
389 | @code{grep}, so as to search every file in a directory tree. See also | |
390 | the @code{find-grep-dired} command, in @ref{Dired and Find}. | |
391 | ||
b5eb27b3 KS |
392 | @findex lgrep |
393 | @findex rgrep | |
394 | The commands @kbd{M-x lgrep} (local grep) and @kbd{M-x rgrep} | |
395 | (recursive grep) are more user-friendly versions of @code{grep} and | |
396 | @code{grep-find}, which prompt separately for the regular expression | |
397 | to match, the files to search, and the base directory for the search | |
8a75579f | 398 | (rgrep only). Case sensitivity of the search is controlled by the |
b5eb27b3 KS |
399 | current value of @code{case-fold-search}. |
400 | ||
401 | These commands build the shell commands based on the variables | |
402 | @code{grep-template} (for @code{lgrep}) and @code{grep-find-template} | |
403 | (for @code{rgrep}). | |
404 | ||
405 | The files to search can use aliases defined in the variable | |
406 | @code{grep-files-aliases}. | |
407 | ||
408 | Subdirectories listed in the variable | |
409 | @code{grep-find-ignored-directories} such as those typically used by | |
410 | various version control systems, like CVS and arch, are automatically | |
411 | skipped by @code{rgrep}. | |
412 | ||
ff994d96 RS |
413 | @node Flymake |
414 | @section Finding Syntax Errors On The Fly | |
415 | @cindex checking syntax | |
416 | ||
417 | Flymake mode is a minor mode that performs on-the-fly syntax | |
418 | checking for many programming and markup languages, including C, C++, | |
419 | Perl, HTML, and @TeX{}/La@TeX{}. It is somewhat analogous to Flyspell | |
420 | mode, which performs spell checking for ordinary human languages in a | |
421 | similar fashion (@pxref{Spelling}). As you edit a file, Flymake mode | |
422 | runs an appropriate syntax checking tool in the background, using a | |
423 | temporary copy of the buffer. It then parses the error and warning | |
424 | messages, and highlights the erroneous lines in the buffer. The | |
425 | syntax checking tool used depends on the language; for example, for | |
426 | C/C++ files this is usually the C compiler. Flymake can also use | |
427 | build tools such as @code{make} for checking complicated projects. | |
428 | ||
429 | To activate Flymake mode, type @kbd{M-x flymake-mode}. You can move | |
430 | to the errors spotted by Flymake mode with @kbd{M-x | |
431 | flymake-goto-next-error} and @kbd{M-x flymake-goto-prev-error}. To | |
432 | display any error messages associated with the current line, use | |
433 | @kbd{M-x flymake-display-err-menu-for-current-line}. | |
434 | ||
435 | For more details about using Flymake, see @ref{Top, Flymake, | |
436 | Flymake, flymake, The Flymake Manual}. | |
437 | ||
6bf7aab6 DL |
438 | @node Debuggers |
439 | @section Running Debuggers Under Emacs | |
440 | @cindex debuggers | |
441 | @cindex GUD library | |
442 | @cindex GDB | |
443 | @cindex DBX | |
444 | @cindex SDB | |
445 | @cindex XDB | |
446 | @cindex Perldb | |
ed4389af | 447 | @cindex bashdb |
6bf7aab6 DL |
448 | @cindex JDB |
449 | @cindex PDB | |
450 | ||
451 | @c Do you believe in GUD? | |
452 | The GUD (Grand Unified Debugger) library provides an interface to | |
31b4c1b7 | 453 | various symbolic debuggers from within Emacs. We recommend the |
41f633c1 RS |
454 | debugger GDB, which is free software, but GUD can also run DBX, SDB or |
455 | XDB. GUD can also serve as an interface to Perl's debugging mode, the | |
456 | Python debugger PDB, the Bash debugger, and to JDB, the Java Debugger. | |
457 | @xref{Debugging,, The Lisp Debugger, elisp, the Emacs Lisp Reference | |
458 | Manual}, for information on debugging Emacs Lisp programs. | |
6bf7aab6 DL |
459 | |
460 | @menu | |
461 | * Starting GUD:: How to start a debugger subprocess. | |
462 | * Debugger Operation:: Connection between the debugger and source buffers. | |
463 | * Commands of GUD:: Key bindings for common commands. | |
464 | * GUD Customization:: Defining your own commands for GUD. | |
f9ad161b RS |
465 | * GDB Graphical Interface:: An enhanced mode that uses GDB features to |
466 | implement a graphical debugging environment through | |
467 | Emacs. | |
6bf7aab6 DL |
468 | @end menu |
469 | ||
470 | @node Starting GUD | |
471 | @subsection Starting GUD | |
472 | ||
473 | There are several commands for starting a debugger, each corresponding | |
474 | to a particular debugger program. | |
475 | ||
476 | @table @kbd | |
477 | @item M-x gdb @key{RET} @var{file} @key{RET} | |
478 | @findex gdb | |
41f633c1 RS |
479 | Run GDB as a subprocess of Emacs. By default, this uses an IDE-like |
480 | graphical interface; see @ref{GDB Graphical Interface}. Only GDB | |
481 | works with the graphical interface. | |
f9ad161b | 482 | |
6bf7aab6 DL |
483 | @item M-x dbx @key{RET} @var{file} @key{RET} |
484 | @findex dbx | |
41f633c1 RS |
485 | Run DBX as a subprocess of Emacs. Since Emacs does not implement a |
486 | graphical interface for DBX, communication with DBX works by typing | |
487 | commands in the GUD interaction buffer. The same is true for all | |
488 | the other supported debuggers. | |
6bf7aab6 DL |
489 | |
490 | @item M-x xdb @key{RET} @var{file} @key{RET} | |
491 | @findex xdb | |
492 | @vindex gud-xdb-directories | |
41f633c1 | 493 | Similar, but run XDB. Use the variable |
6bf7aab6 DL |
494 | @code{gud-xdb-directories} to specify directories to search for source |
495 | files. | |
496 | ||
497 | @item M-x sdb @key{RET} @var{file} @key{RET} | |
498 | @findex sdb | |
41f633c1 | 499 | Similar, but run SDB. |
6bf7aab6 DL |
500 | |
501 | Some versions of SDB do not mention source file names in their | |
502 | messages. When you use them, you need to have a valid tags table | |
503 | (@pxref{Tags}) in order for GUD to find functions in the source code. | |
504 | If you have not visited a tags table or the tags table doesn't list one | |
505 | of the functions, you get a message saying @samp{The sdb support | |
506 | requires a valid tags table to work}. If this happens, generate a valid | |
507 | tags table in the working directory and try again. | |
508 | ||
ed4389af RS |
509 | @item M-x bashdb @key{RET} @var{file} @key{RET} |
510 | @findex bashdb | |
511 | Run the bash debugger to debug @var{file}, a shell script. | |
512 | ||
6bf7aab6 DL |
513 | @item M-x perldb @key{RET} @var{file} @key{RET} |
514 | @findex perldb | |
515 | Run the Perl interpreter in debug mode to debug @var{file}, a Perl program. | |
516 | ||
517 | @item M-x jdb @key{RET} @var{file} @key{RET} | |
518 | @findex jdb | |
519 | Run the Java debugger to debug @var{file}. | |
520 | ||
521 | @item M-x pdb @key{RET} @var{file} @key{RET} | |
522 | @findex pdb | |
523 | Run the Python debugger to debug @var{file}. | |
524 | @end table | |
525 | ||
526 | Each of these commands takes one argument: a command line to invoke | |
527 | the debugger. In the simplest case, specify just the name of the | |
528 | executable file you want to debug. You may also use options that the | |
529 | debugger supports. However, shell wildcards and variables are not | |
530 | allowed. GUD assumes that the first argument not starting with a | |
531 | @samp{-} is the executable file name. | |
532 | ||
6bf7aab6 DL |
533 | @node Debugger Operation |
534 | @subsection Debugger Operation | |
535 | ||
3605e23f | 536 | @cindex fringes, and current execution line in GUD |
41f633c1 RS |
537 | When you run a debugger with GUD using the textual interface, the |
538 | debugger uses an Emacs buffer for its ordinary input and output. This | |
539 | is called the GUD buffer. Input and output from the program you are | |
540 | debugging also use this buffer. | |
541 | ||
542 | The debugger displays the source files of the program by visiting | |
543 | them in Emacs buffers. An arrow in the left fringe indicates the | |
544 | current execution line.@footnote{On a text-only terminal, the arrow | |
545 | appears as @samp{=>} and overlays the first two text columns.} Moving | |
546 | point in this buffer does not move the arrow. The arrow is not part | |
547 | of the file's text; it appears only on the screen. | |
6bf7aab6 DL |
548 | |
549 | You can start editing these source files at any time in the buffers | |
41f633c1 RS |
550 | that display them. If you do modify a source file, keep in mind that |
551 | inserting or deleting lines will throw off the arrow's positioning; | |
552 | GUD has no way of figuring out which line corresponded before your | |
553 | changes to the line number in a debugger message. Also, you'll | |
554 | typically have to recompile and restart the program for your changes | |
555 | to be reflected in the debugger's tables. | |
6bf7aab6 | 556 | |
499de9ba RS |
557 | @cindex tooltips with GUD |
558 | @vindex tooltip-gud-modes | |
c2332b4f NR |
559 | @vindex gud-tooltip-mode |
560 | @vindex gud-tooltip-echo-area | |
499de9ba | 561 | The Tooltip facility (@pxref{Tooltips}) provides support for GUD@. |
8a25d51a NR |
562 | You activate this feature by turning on the minor mode |
563 | @code{gud-tooltip-mode}. Then you can display a variable's value in a | |
564 | tooltip simply by pointing at it with the mouse. In graphical mode, | |
565 | with a C program, you can also display the @code{#define} directive | |
566 | associated with an identifier when the program is not executing. This | |
567 | operates in the GUD buffer and in source buffers with major modes in | |
c2332b4f | 568 | the list @code{gud-tooltip-modes}. If the variable |
cb7b02c7 NR |
569 | @code{gud-tooltip-echo-area} is non-@code{nil} then the variable's |
570 | value is displayed in the echo area. | |
499de9ba | 571 | |
41f633c1 RS |
572 | GUD tooltips are disabled when you use GDB in text command mode |
573 | (@pxref{GDB Graphical Interface}), because displaying an expression's | |
574 | value in GDB can sometimes expand a macro and result in a side effect | |
575 | that interferes with the program's operation. The GDB graphical | |
576 | interface supports GUD tooltips and assures they will not cause side | |
577 | effects. | |
b376642d | 578 | |
6bf7aab6 DL |
579 | @node Commands of GUD |
580 | @subsection Commands of GUD | |
581 | ||
582 | The GUD interaction buffer uses a variant of Shell mode, so the | |
41f633c1 RS |
583 | Emacs commands of Shell mode are available (@pxref{Shell Mode}). All |
584 | the usual commands for your debugger are available, and you can use | |
585 | the Shell mode history commands to repeat them. If you wish, you can | |
586 | control your debugger process entirely through this buffer. | |
587 | ||
588 | GUD mode also provides commands for setting and clearing | |
589 | breakpoints, for selecting stack frames, and for stepping through the | |
590 | program. These commands are available both in the GUD buffer and | |
591 | globally, but with different key bindings. It also has its own tool | |
592 | bar from which you can invoke the more common commands by clicking on | |
593 | the appropriate icon. This is particularly useful for repetitive | |
594 | commands like @code{gud-next} and @code{gud-step}, and allows you to | |
595 | keep the GUD buffer hidden. | |
6bf7aab6 | 596 | |
58fa012d EZ |
597 | The breakpoint commands are normally used in source file buffers, |
598 | because that is the easiest way to specify where to set or clear the | |
599 | breakpoint. Here's the global command to set a breakpoint: | |
6bf7aab6 DL |
600 | |
601 | @table @kbd | |
602 | @item C-x @key{SPC} | |
603 | @kindex C-x SPC | |
604 | Set a breakpoint on the source line that point is on. | |
605 | @end table | |
606 | ||
607 | @kindex C-x C-a @r{(GUD)} | |
41f633c1 | 608 | Here are the other special commands provided by GUD@. The keys |
6bf7aab6 | 609 | starting with @kbd{C-c} are available only in the GUD interaction |
55d5a463 NR |
610 | buffer. The key bindings that start with @kbd{C-x C-a} are available |
611 | in the GUD interaction buffer and also in source files. Some of these | |
612 | commands are not available to all the supported debuggers. | |
6bf7aab6 DL |
613 | |
614 | @table @kbd | |
615 | @item C-c C-l | |
616 | @kindex C-c C-l @r{(GUD)} | |
617 | @itemx C-x C-a C-l | |
618 | @findex gud-refresh | |
619 | Display in another window the last line referred to in the GUD | |
620 | buffer (that is, the line indicated in the last location message). | |
621 | This runs the command @code{gud-refresh}. | |
622 | ||
623 | @item C-c C-s | |
624 | @kindex C-c C-s @r{(GUD)} | |
625 | @itemx C-x C-a C-s | |
626 | @findex gud-step | |
627 | Execute a single line of code (@code{gud-step}). If the line contains | |
628 | a function call, execution stops after entering the called function. | |
629 | ||
630 | @item C-c C-n | |
631 | @kindex C-c C-n @r{(GUD)} | |
632 | @itemx C-x C-a C-n | |
633 | @findex gud-next | |
634 | Execute a single line of code, stepping across entire function calls | |
635 | at full speed (@code{gud-next}). | |
636 | ||
637 | @item C-c C-i | |
638 | @kindex C-c C-i @r{(GUD)} | |
639 | @itemx C-x C-a C-i | |
640 | @findex gud-stepi | |
641 | Execute a single machine instruction (@code{gud-stepi}). | |
642 | ||
55d5a463 NR |
643 | @item C-c C-p |
644 | @kindex C-c C-p @r{(GUD)} | |
645 | @itemx C-x C-a C-p | |
646 | @findex gud-print | |
647 | Evaluate the expression at point (@code{gud-print}). If Emacs | |
648 | does not print the exact expression that you want, mark it as a region | |
649 | first. | |
650 | ||
6bf7aab6 DL |
651 | @need 3000 |
652 | @item C-c C-r | |
653 | @kindex C-c C-r @r{(GUD)} | |
654 | @itemx C-x C-a C-r | |
655 | @findex gud-cont | |
656 | Continue execution without specifying any stopping point. The program | |
657 | will run until it hits a breakpoint, terminates, or gets a signal that | |
658 | the debugger is checking for (@code{gud-cont}). | |
659 | ||
660 | @need 1000 | |
661 | @item C-c C-d | |
662 | @kindex C-c C-d @r{(GUD)} | |
663 | @itemx C-x C-a C-d | |
664 | @findex gud-remove | |
665 | Delete the breakpoint(s) on the current source line, if any | |
666 | (@code{gud-remove}). If you use this command in the GUD interaction | |
667 | buffer, it applies to the line where the program last stopped. | |
668 | ||
669 | @item C-c C-t | |
670 | @kindex C-c C-t @r{(GUD)} | |
671 | @itemx C-x C-a C-t | |
672 | @findex gud-tbreak | |
41f633c1 RS |
673 | Set a temporary breakpoint on the current source line, if any |
674 | (@code{gud-tbreak}). If you use this command in the GUD interaction | |
675 | buffer, it applies to the line where the program last stopped. | |
6bf7aab6 | 676 | |
6bf7aab6 DL |
677 | @item C-c < |
678 | @kindex C-c < @r{(GUD)} | |
679 | @itemx C-x C-a < | |
680 | @findex gud-up | |
681 | Select the next enclosing stack frame (@code{gud-up}). This is | |
41f633c1 | 682 | equivalent to the GDB command @samp{up}. |
6bf7aab6 DL |
683 | |
684 | @item C-c > | |
685 | @kindex C-c > @r{(GUD)} | |
686 | @itemx C-x C-a > | |
687 | @findex gud-down | |
688 | Select the next inner stack frame (@code{gud-down}). This is | |
41f633c1 | 689 | equivalent to the GDB command @samp{down}. |
f9ad161b RS |
690 | |
691 | @item C-c C-u | |
692 | @kindex C-c C-u @r{(GUD)} | |
693 | @itemx C-x C-a C-u | |
694 | @findex gud-until | |
41f633c1 RS |
695 | Continue execution to the current line (@code{gud-until}). The |
696 | program will run until it hits a breakpoint, terminates, gets a signal | |
697 | that the debugger is checking for, or reaches the line on which the | |
698 | cursor currently sits. | |
f9ad161b | 699 | |
6bf7aab6 DL |
700 | @item C-c C-f |
701 | @kindex C-c C-f @r{(GUD)} | |
702 | @itemx C-x C-a C-f | |
703 | @findex gud-finish | |
b5eb27b3 | 704 | Run the program until the selected stack frame returns or |
41f633c1 | 705 | stops for some other reason (@code{gud-finish}). |
55d5a463 NR |
706 | @end table |
707 | ||
708 | If you are using GDB, these additional key bindings are available: | |
5b7fc395 | 709 | |
55d5a463 | 710 | @table @kbd |
44fa0ae8 RS |
711 | @item C-x C-a C-j |
712 | @kindex C-x C-a C-j @r{(GUD)} | |
5b7fc395 | 713 | @findex gud-jump |
41f633c1 | 714 | Only useful in a source buffer, @code{gud-jump} transfers the |
44fa0ae8 RS |
715 | program's execution point to the current line. In other words, the |
716 | next line that the program executes will be the one where you gave the | |
717 | command. If the new execution line is in a different function from | |
718 | the previously one, GDB prompts for confirmation since the results may | |
719 | be bizarre. See the GDB manual entry regarding @code{jump} for | |
720 | details. | |
55d5a463 NR |
721 | |
722 | @item @key{TAB} | |
723 | @kindex TAB @r{(GUD)} | |
724 | @findex gud-gdb-complete-command | |
725 | With GDB, complete a symbol name (@code{gud-gdb-complete-command}). | |
726 | This key is available only in the GUD interaction buffer. | |
6bf7aab6 DL |
727 | @end table |
728 | ||
729 | These commands interpret a numeric argument as a repeat count, when | |
730 | that makes sense. | |
731 | ||
732 | Because @key{TAB} serves as a completion command, you can't use it to | |
733 | enter a tab as input to the program you are debugging with GDB. | |
734 | Instead, type @kbd{C-q @key{TAB}} to enter a tab. | |
735 | ||
736 | @node GUD Customization | |
737 | @subsection GUD Customization | |
738 | ||
739 | @vindex gdb-mode-hook | |
740 | @vindex dbx-mode-hook | |
741 | @vindex sdb-mode-hook | |
742 | @vindex xdb-mode-hook | |
743 | @vindex perldb-mode-hook | |
744 | @vindex pdb-mode-hook | |
745 | @vindex jdb-mode-hook | |
41f633c1 | 746 | @vindex bashdb-mode-hook |
6bf7aab6 DL |
747 | On startup, GUD runs one of the following hooks: @code{gdb-mode-hook}, |
748 | if you are using GDB; @code{dbx-mode-hook}, if you are using DBX; | |
749 | @code{sdb-mode-hook}, if you are using SDB; @code{xdb-mode-hook}, if you | |
750 | are using XDB; @code{perldb-mode-hook}, for Perl debugging mode; | |
41f633c1 RS |
751 | @code{pdb-mode-hook}, for PDB; @code{jdb-mode-hook}, for JDB; |
752 | @code{bashdb-mode-hook}, for the Bash debugger. You can | |
6bf7aab6 DL |
753 | use these hooks to define custom key bindings for the debugger |
754 | interaction buffer. @xref{Hooks}. | |
755 | ||
756 | Here is a convenient way to define a command that sends a particular | |
757 | command string to the debugger, and set up a key binding for it in the | |
758 | debugger interaction buffer: | |
759 | ||
760 | @findex gud-def | |
761 | @example | |
762 | (gud-def @var{function} @var{cmdstring} @var{binding} @var{docstring}) | |
763 | @end example | |
764 | ||
765 | This defines a command named @var{function} which sends | |
766 | @var{cmdstring} to the debugger process, and gives it the documentation | |
7fb4961c | 767 | string @var{docstring}. You can then use the command @var{function} in any |
6bf7aab6 DL |
768 | buffer. If @var{binding} is non-@code{nil}, @code{gud-def} also binds |
769 | the command to @kbd{C-c @var{binding}} in the GUD buffer's mode and to | |
770 | @kbd{C-x C-a @var{binding}} generally. | |
771 | ||
772 | The command string @var{cmdstring} may contain certain | |
773 | @samp{%}-sequences that stand for data to be filled in at the time | |
774 | @var{function} is called: | |
775 | ||
776 | @table @samp | |
777 | @item %f | |
778 | The name of the current source file. If the current buffer is the GUD | |
779 | buffer, then the ``current source file'' is the file that the program | |
780 | stopped in. | |
6bf7aab6 DL |
781 | |
782 | @item %l | |
783 | The number of the current source line. If the current buffer is the GUD | |
784 | buffer, then the ``current source line'' is the line that the program | |
785 | stopped in. | |
786 | ||
787 | @item %e | |
d6802fc1 NR |
788 | In transient-mark-mode the text in the region, if it is active. |
789 | Otherwise the text of the C lvalue or function-call expression at or | |
790 | adjacent to point. | |
6bf7aab6 DL |
791 | |
792 | @item %a | |
793 | The text of the hexadecimal address at or adjacent to point. | |
794 | ||
795 | @item %p | |
796 | The numeric argument of the called function, as a decimal number. If | |
797 | the command is used without a numeric argument, @samp{%p} stands for the | |
798 | empty string. | |
799 | ||
800 | If you don't use @samp{%p} in the command string, the command you define | |
801 | ignores any numeric argument. | |
d6802fc1 NR |
802 | |
803 | @item %d | |
804 | The name of the directory of the current source file. | |
805 | ||
806 | @item %c | |
807 | Fully qualified class name derived from the expression surrounding point | |
808 | (jdb only). | |
6bf7aab6 DL |
809 | @end table |
810 | ||
f9ad161b RS |
811 | @node GDB Graphical Interface |
812 | @subsection GDB Graphical Interface | |
813 | ||
499de9ba | 814 | By default, the command @code{gdb} starts GDB using a graphical |
41f633c1 RS |
815 | interface, using Emacs windows for display program state information. |
816 | In effect, this makes Emacs into an IDE (interactive development | |
817 | environment). With it, you do not need to use textual GDB commands; | |
fc275000 NR |
818 | you can control the debugging session with the mouse. For example, |
819 | you can click in the fringe of a source buffer to set a breakpoint | |
820 | there, or on a stack frame in the stack buffer to select that frame. | |
41f633c1 RS |
821 | |
822 | This mode requires telling GDB that its ``screen size'' is | |
823 | unlimited, so it sets the height and width accordingly. For correct | |
824 | operation you must not change these values during the GDB session. | |
51344076 | 825 | |
499de9ba | 826 | @vindex gud-gdb-command-name |
f9ad161b | 827 | @findex gdba |
41f633c1 RS |
828 | You can also run GDB in text command mode, like other debuggers. To |
829 | do this, set @code{gud-gdb-command-name} to @code{"gdb --fullname"} or | |
830 | edit the startup command in the minibuffer to say that. You need to | |
831 | do use text command mode to run multiple debugging sessions within one | |
832 | Emacs session. If you have customized @code{gud-gdb-command-name} in | |
833 | that way, you can use @kbd{M-x gdba} to invoke GDB in graphical mode. | |
f9ad161b RS |
834 | |
835 | @menu | |
be0f250c | 836 | * GDB-UI Layout:: Control the number of displayed buffers. |
988fd256 NR |
837 | * Source Buffers:: Use the mouse in the fringe/margin to |
838 | control your program. | |
3e2546d7 NR |
839 | * Breakpoints Buffer:: A breakpoint control panel. |
840 | * Stack Buffer:: Select a frame from the call stack. | |
be0f250c | 841 | * Other GDB-UI Buffers:: Input/output, locals, registers, |
f72b052c | 842 | assembler, threads and memory buffers. |
fc275000 | 843 | * Watch Expressions:: Monitor variable values in the speedbar. |
f9ad161b RS |
844 | @end menu |
845 | ||
be0f250c | 846 | @node GDB-UI Layout |
3e2546d7 | 847 | @subsubsection GDB User Interface Layout |
96110242 NR |
848 | @cindex GDB User Interface layout |
849 | ||
96110242 | 850 | @vindex gdb-many-windows |
41f633c1 RS |
851 | If the variable @code{gdb-many-windows} is @code{nil} (the default |
852 | value) then @kbd{M-x gdb} normally displays only the GUD buffer. | |
853 | However, if the variable @code{gdb-show-main} is also non-@code{nil}, | |
854 | it starts with two windows: one displaying the GUD buffer, and the | |
855 | other showing the source for the @code{main} function of the program | |
856 | you are debugging. | |
96110242 | 857 | |
41f633c1 RS |
858 | If @code{gdb-many-windows} is non-@code{nil}, then @kbd{M-x gdb} |
859 | displays the following frame layout: | |
96110242 | 860 | |
444246ca KB |
861 | @smallexample |
862 | @group | |
1a0b66fe | 863 | +--------------------------------+--------------------------------+ |
31d7d340 | 864 | | GUD buffer (I/O of GDB) | Locals buffer | |
1a0b66fe | 865 | |--------------------------------+--------------------------------+ |
988fd256 | 866 | | Primary Source buffer | I/O buffer for debugged pgm | |
1a0b66fe | 867 | |--------------------------------+--------------------------------+ |
31d7d340 | 868 | | Stack buffer | Breakpoints buffer | |
1a0b66fe | 869 | +--------------------------------+--------------------------------+ |
444246ca KB |
870 | @end group |
871 | @end smallexample | |
96110242 | 872 | |
9fb0c6f5 | 873 | However, if @code{gdb-use-separate-io-buffer} is @code{nil}, the I/O |
988fd256 NR |
874 | buffer does not appear and the primary source buffer occupies the full |
875 | width of the frame. | |
96110242 NR |
876 | |
877 | @findex gdb-restore-windows | |
41f633c1 RS |
878 | If you change the window layout, for example, while editing and |
879 | re-compiling your program, then you can restore this standard window | |
880 | layout with the command @code{gdb-restore-windows}. | |
881 | ||
882 | @findex gdb-many-windows | |
883 | To switch between this standard layout and a simple layout | |
884 | containing just the GUD buffer and a source file, type @kbd{M-x | |
885 | gdb-many-windows}. | |
886 | ||
be0f250c | 887 | You may also specify additional GDB-related buffers to display, |
41f633c1 RS |
888 | either in the same frame or a different one. Select the buffers you |
889 | want with the @samp{GUD->GDB-windows} and @samp{GUD->GDB-Frames} | |
890 | sub-menus. If the menu-bar is unavailable, type @code{M-x | |
96110242 | 891 | gdb-display-@var{buffertype}-buffer} or @code{M-x |
1a0b66fe | 892 | gdb-frame-@var{buffertype}-buffer} respectively, where |
41f633c1 RS |
893 | @var{buffertype} is the relevant buffer type, such as |
894 | @samp{breakpoints}. Most of these buffers are read-only, and typing | |
895 | @kbd{q} in them kills them. | |
96110242 | 896 | |
41f633c1 | 897 | When you finish debugging, kill the GUD buffer with @kbd{C-x k}, |
31b4c1b7 NR |
898 | which will also kill all the buffers associated with the session. |
899 | However you need not do this if, after editing and re-compiling your | |
900 | source code within Emacs, you wish continue debugging. When you | |
901 | restart execution, GDB will automatically find your new executable. | |
902 | Keeping the GUD buffer has the advantage of keeping the shell history | |
41f633c1 RS |
903 | as well as GDB's breakpoints. You do need to check that the |
904 | breakpoints in recently edited source files are still in the right | |
905 | places. | |
31b4c1b7 | 906 | |
988fd256 NR |
907 | @node Source Buffers |
908 | @subsubsection Source Buffers | |
909 | @cindex GDB commands in Fringe | |
910 | ||
911 | @c @findex gdb-mouse-set-clear-breakpoint | |
912 | @c @findex gdb-mouse-toggle-breakpoint | |
913 | Many GDB commands can be entered using keybindings or the tool bar but | |
914 | sometimes it is quicker to use the fringe. These commands either | |
915 | manipulate breakpoints or control program execution. When there is no | |
916 | fringe, you can use the margin but this is only present when the | |
917 | source file already has a breakpoint. | |
918 | ||
919 | You can click @kbd{Mouse-1} in the fringe or display margin of a | |
920 | source buffer to set a breakpoint there and, on a graphical display, a | |
921 | red bullet will appear on that line. If a breakpoint already exists | |
922 | on that line, the same click will remove it. You can also enable or | |
923 | disable a breakpoint by clicking @kbd{C-Mouse-1} on the bullet. | |
924 | ||
925 | A solid arrow in the left fringe of a source buffer indicates the line | |
926 | of the innermost frame where the debugged program has stopped. A | |
927 | hollow arrow indicates the current execution line of higher level | |
928 | frames. | |
929 | ||
930 | If you drag the arrow in the fringe with @kbd{Mouse-1} | |
931 | (@code{gdb-mouse-until}), execution will continue to the line where | |
932 | you release the button, provided it is still in the same frame. | |
933 | Alternatively, you can click @kbd{Mouse-3} at some point in the fringe | |
934 | of this buffer and execution will advance to there. A similar command | |
935 | (@code{gdb-mouse-jump}) allows you to jump to a source line without | |
936 | executing the intermediate lines by clicking @kbd{C-Mouse-3}. This | |
937 | command allows you to go backwards which can be useful for running | |
938 | through code that has already executed, in order to examine its | |
939 | execution in more detail. | |
940 | ||
941 | @table @kbd | |
942 | @item Mouse-1 | |
943 | Set or clear a breakpoint. | |
944 | ||
945 | @item C-Mouse-1 | |
946 | Enable or disable a breakpoint. | |
947 | ||
948 | @item Mouse-3 | |
949 | Continue execution to here. | |
950 | ||
951 | @item C-Mouse-3 | |
952 | Jump to here. | |
953 | @end table | |
954 | ||
955 | If the variable @code{gdb-find-source-frame} is non-@code{nil} and | |
956 | execution stops in a frame for which there is no source code e.g after | |
957 | an interrupt, then Emacs finds and displays the first frame further up | |
958 | stack for which there is source. If it is @code{nil} then the source | |
959 | buffer continues to display the last frame which maybe more useful, | |
960 | for example, when re-setting a breakpoint. | |
961 | ||
f9ad161b RS |
962 | @node Breakpoints Buffer |
963 | @subsubsection Breakpoints Buffer | |
964 | ||
41f633c1 RS |
965 | The breakpoints buffer shows the existing breakpoints and |
966 | watchpoints (@pxref{Breakpoints,,, gdb, The GNU debugger}). It has | |
967 | these special commands, which mostly apply to the @dfn{current | |
968 | breakpoint}, the breakpoint which point is on. | |
f9ad161b RS |
969 | |
970 | @table @kbd | |
254196f5 | 971 | @item @key{SPC} |
f9ad161b RS |
972 | @kindex SPC @r{(GDB breakpoints buffer)} |
973 | @findex gdb-toggle-breakpoint | |
41f633c1 RS |
974 | Enable/disable the current breakpoint (@code{gdb-toggle-breakpoint}). |
975 | On a graphical display, this changes the color of a bullet in the | |
988fd256 | 976 | margin of a source buffer at the relevant line. This is red when |
41f633c1 RS |
977 | the breakpoint is enabled and grey when it is disabled. Text-only |
978 | terminals correspondingly display a @samp{B} or @samp{b}. | |
f9ad161b | 979 | |
c3287027 NR |
980 | @item D |
981 | @kindex D @r{(GDB breakpoints buffer)} | |
f9ad161b | 982 | @findex gdb-delete-breakpoint |
41f633c1 | 983 | Delete the current breakpoint (@code{gdb-delete-breakpoint}). |
f9ad161b RS |
984 | |
985 | @item @key{RET} | |
986 | @kindex RET @r{(GDB breakpoints buffer)} | |
987 | @findex gdb-goto-breakpoint | |
41f633c1 RS |
988 | Visit the source line for the current breakpoint |
989 | (@code{gdb-goto-breakpoint}). | |
990 | ||
991 | @item Mouse-2 | |
992 | @kindex Mouse-2 @r{(GDB breakpoints buffer)} | |
993 | Visit the source line for the breakpoint you click on. | |
f9ad161b RS |
994 | @end table |
995 | ||
996 | @node Stack Buffer | |
997 | @subsubsection Stack Buffer | |
998 | ||
41f633c1 | 999 | The stack buffer displays a @dfn{call stack}, with one line for each |
f9ad161b | 1000 | of the nested subroutine calls (@dfn{stack frames}) now active in the |
1a0b66fe | 1001 | program. @xref{Backtrace,, Backtraces, gdb, The GNU debugger}. |
f9ad161b | 1002 | |
e4481965 | 1003 | @findex gdb-frames-select |
a7acd30f NR |
1004 | An arrow in the fringe points to the selected frame or, if the fringe is |
1005 | not present, the number of the selected frame is displayed in reverse | |
1006 | contrast. To select a frame in GDB, move point in the stack buffer to | |
1007 | that stack frame and type @key{RET} (@code{gdb-frames-select}), or click | |
41f633c1 | 1008 | @kbd{Mouse-2} on a stack frame. If the locals buffer is visible, |
a7acd30f NR |
1009 | selecting a stack frame updates it to display the local variables of the |
1010 | new frame. | |
f9ad161b | 1011 | |
be0f250c | 1012 | @node Other GDB-UI Buffers |
f9ad161b RS |
1013 | @subsubsection Other Buffers |
1014 | ||
1015 | @table @asis | |
1016 | @item Input/Output Buffer | |
9fb0c6f5 NR |
1017 | @vindex gdb-use-separate-io-buffer |
1018 | If the variable @code{gdb-use-separate-io-buffer} is non-@code{nil}, | |
be0f250c NR |
1019 | the program being debugged takes its input and displays its output |
1020 | here. Otherwise it uses the GUD buffer for that. To toggle whether | |
1021 | GUD mode uses this buffer, do @kbd{M-x gdb-use-separate-io-buffer}. | |
a7acd30f | 1022 | This takes effect when you next restart the program you are debugging. |
d08a1c88 | 1023 | |
cf3a96a3 | 1024 | The history and replay commands from Shell mode are available here, |
be0f250c | 1025 | as are the commands to send signals to the debugged program. |
cf3a96a3 | 1026 | @xref{Shell Mode}. |
f9ad161b RS |
1027 | |
1028 | @item Locals Buffer | |
1029 | The locals buffer displays the values of local variables of the | |
1a0b66fe | 1030 | current frame for simple data types (@pxref{Frame Info, Frame Info, |
b1333d4f NR |
1031 | Information on a frame, gdb, The GNU debugger}). Press @key{RET} or |
1032 | click @kbd{Mouse-2} on the value if you want to edit it. | |
f9ad161b | 1033 | |
51344076 NR |
1034 | Arrays and structures display their type only. With GDB 6.4 or later, |
1035 | move point to their name and press @key{RET}, or alternatively click | |
1036 | @kbd{Mouse-2} there, to examine their values. With earlier versions | |
cf3a96a3 RS |
1037 | of GDB, use @kbd{Mouse-2} or @key{RET} on the type description |
1038 | (@samp{[struct/union]} or @samp{[array]}). @xref{Watch Expressions}. | |
f9ad161b RS |
1039 | |
1040 | @item Registers Buffer | |
e4481965 | 1041 | @findex toggle-gdb-all-registers |
f9ad161b | 1042 | The registers buffer displays the values held by the registers |
c3287027 | 1043 | (@pxref{Registers,,, gdb, The GNU debugger}). Press @key{RET} or |
b1333d4f | 1044 | click @kbd{Mouse-2} on a register if you want to edit its value. |
51344076 | 1045 | With GDB 6.4 or later, recently changed register values display with |
41f633c1 RS |
1046 | @code{font-lock-warning-face}. With earlier versions of GDB, you can |
1047 | press @key{SPC} to toggle the display of floating point registers | |
e4481965 | 1048 | (@code{toggle-gdb-all-registers}). |
f9ad161b RS |
1049 | |
1050 | @item Assembler Buffer | |
1051 | The assembler buffer displays the current frame as machine code. An | |
41f633c1 RS |
1052 | arrow points to the current instruction, and you can set and remove |
1053 | breakpoints as in a source buffer. Breakpoint icons also appear in | |
1054 | the fringe or margin. | |
8d66c08b NR |
1055 | |
1056 | @item Threads Buffer | |
e4481965 | 1057 | @findex gdb-threads-select |
8d66c08b | 1058 | The threads buffer displays a summary of all threads currently in your |
1a0b66fe NR |
1059 | program (@pxref{Threads, Threads, Debugging programs with multiple |
1060 | threads, gdb, The GNU debugger}). Move point to any thread in the | |
1061 | list and press @key{RET} to select it (@code{gdb-threads-select}) and | |
988fd256 NR |
1062 | display the associated source in the primary source buffer. |
1063 | Alternatively, click @kbd{Mouse-2} on a thread to select it. If the | |
1064 | locals buffer is visible, its contents update to display the variables | |
1065 | that are local in the new thread. | |
8d66c08b | 1066 | |
31b4c1b7 | 1067 | @item Memory Buffer |
41f633c1 RS |
1068 | The memory buffer lets you examine sections of program memory |
1069 | (@pxref{Memory, Memory, Examining memory, gdb, The GNU debugger}). | |
1070 | Click @kbd{Mouse-1} on the appropriate part of the header line to | |
1071 | change the starting address or number of data items that the buffer | |
1072 | displays. Click @kbd{Mouse-3} on the header line to select the | |
1a0b66fe | 1073 | display format or unit size for these data items. |
fc275000 NR |
1074 | @end table |
1075 | ||
fc275000 NR |
1076 | @node Watch Expressions |
1077 | @subsubsection Watch Expressions | |
1078 | @cindex Watching expressions in GDB | |
1079 | ||
1080 | @findex gud-watch | |
1081 | @kindex C-x C-a C-w @r{(GUD)} | |
1082 | If you want to see how a variable changes each time your program | |
1083 | stops, move point into the variable name and click on the watch icon | |
1084 | in the tool bar (@code{gud-watch}) or type @kbd{C-x C-a C-w}. If you | |
1085 | specify a prefix argument, you can enter the variable name in the | |
1086 | minibuffer. | |
1087 | ||
1088 | Each watch expression is displayed in the speedbar. Complex data | |
1089 | types, such as arrays, structures and unions are represented in a tree | |
1090 | format. Leaves and simple data types show the name of the expression | |
1091 | and its value and, when the speedbar frame is selected, display the | |
1092 | type as a tooltip. Higher levels show the name, type and address | |
1093 | value for pointers and just the name and type otherwise. Root expressions | |
1094 | also display the frame address as a tooltip to help identify the frame | |
1095 | in which they were defined. | |
1096 | ||
1097 | To expand or contract a complex data type, click @kbd{Mouse-2} | |
1098 | on the tag to the left of the expression. | |
1099 | ||
1100 | @kindex D @r{(GDB speedbar)} | |
1101 | @findex gdb-var-delete | |
1102 | To delete a complex watch expression, move point to the root | |
1103 | expression in the speedbar and type @kbd{D} (@code{gdb-var-delete}). | |
1104 | ||
1105 | @kindex RET @r{(GDB speedbar)} | |
1106 | @findex gdb-edit-value | |
1107 | To edit a variable with a simple data type, or a simple element of a | |
1108 | complex data type, move point there in the speedbar and type @key{RET} | |
1109 | (@code{gdb-edit-value}). Or you can click @kbd{Mouse-2} on a value to | |
1110 | edit it. Either way, this reads the new value using the minibuffer. | |
1111 | ||
1112 | @vindex gdb-show-changed-values | |
1113 | If you set the variable @code{gdb-show-changed-values} to | |
1114 | non-@code{nil} (the default value), Emacs uses | |
1115 | @code{font-lock-warning-face} to highlight values that have recently | |
1116 | changed and @code{shadow} face to make variables which have gone out of | |
1117 | scope less noticeable. When a variable goes out of scope you can't | |
1118 | edit its value. | |
1119 | ||
1120 | @vindex gdb-use-colon-colon-notation | |
1121 | If the variable @code{gdb-use-colon-colon-notation} is | |
1122 | non-@code{nil}, Emacs uses the @samp{@var{function}::@var{variable}} | |
1123 | format. This allows the user to display watch expressions which share | |
1124 | the same variable name. The default value is @code{nil}. | |
1125 | ||
1126 | @vindex gdb-speedbar-auto-raise | |
1127 | To automatically raise the speedbar every time the display of watch | |
1128 | expressions updates, set @code{gdb-speedbar-auto-raise} to | |
1129 | non-@code{nil}. This can be useful if you are debugging with a full | |
1130 | screen Emacs frame. | |
1131 | ||
6bf7aab6 DL |
1132 | @node Executing Lisp |
1133 | @section Executing Lisp Expressions | |
1134 | ||
1135 | Emacs has several different major modes for Lisp and Scheme. They are | |
1136 | the same in terms of editing commands, but differ in the commands for | |
1137 | executing Lisp expressions. Each mode has its own purpose. | |
1138 | ||
1139 | @table @asis | |
1140 | @item Emacs-Lisp mode | |
1141 | The mode for editing source files of programs to run in Emacs Lisp. | |
1142 | This mode defines @kbd{C-M-x} to evaluate the current defun. | |
1143 | @xref{Lisp Libraries}. | |
1144 | @item Lisp Interaction mode | |
1145 | The mode for an interactive session with Emacs Lisp. It defines | |
1146 | @kbd{C-j} to evaluate the sexp before point and insert its value in the | |
1147 | buffer. @xref{Lisp Interaction}. | |
1148 | @item Lisp mode | |
1149 | The mode for editing source files of programs that run in Lisps other | |
1150 | than Emacs Lisp. This mode defines @kbd{C-M-x} to send the current defun | |
1151 | to an inferior Lisp process. @xref{External Lisp}. | |
1152 | @item Inferior Lisp mode | |
1153 | The mode for an interactive session with an inferior Lisp process. | |
1154 | This mode combines the special features of Lisp mode and Shell mode | |
1155 | (@pxref{Shell Mode}). | |
1156 | @item Scheme mode | |
1157 | Like Lisp mode but for Scheme programs. | |
1158 | @item Inferior Scheme mode | |
1159 | The mode for an interactive session with an inferior Scheme process. | |
1160 | @end table | |
1161 | ||
1162 | Most editing commands for working with Lisp programs are in fact | |
1163 | available globally. @xref{Programs}. | |
1164 | ||
1165 | @node Lisp Libraries | |
1166 | @section Libraries of Lisp Code for Emacs | |
1167 | @cindex libraries | |
1168 | @cindex loading Lisp code | |
1169 | ||
1170 | Lisp code for Emacs editing commands is stored in files whose names | |
1171 | conventionally end in @file{.el}. This ending tells Emacs to edit them in | |
1172 | Emacs-Lisp mode (@pxref{Executing Lisp}). | |
1173 | ||
41f633c1 RS |
1174 | @cindex byte code |
1175 | Emacs Lisp code can be compiled into byte-code, which loads faster, | |
1176 | takes up less space, and executes faster. @xref{Byte Compilation,, | |
1177 | Byte Compilation, elisp, the Emacs Lisp Reference Manual}. By | |
1178 | convention, the compiled code for a library goes in a separate file | |
1179 | whose name ends in @samp{.elc}. Thus, the compiled code for | |
1180 | @file{foo.el} goes in @file{foo.elc}. | |
1181 | ||
6bf7aab6 DL |
1182 | @findex load-file |
1183 | To execute a file of Emacs Lisp code, use @kbd{M-x load-file}. This | |
1184 | command reads a file name using the minibuffer and then executes the | |
1185 | contents of that file as Lisp code. It is not necessary to visit the | |
1186 | file first; in any case, this command reads the file as found on disk, | |
1187 | not text in an Emacs buffer. | |
1188 | ||
1189 | @findex load | |
1190 | @findex load-library | |
1191 | Once a file of Lisp code is installed in the Emacs Lisp library | |
41f633c1 RS |
1192 | directories, users can load it using @kbd{M-x load-library}. Programs |
1193 | can load it by calling @code{load}, a more primitive function that is | |
1194 | similar but accepts some additional arguments. | |
6bf7aab6 DL |
1195 | |
1196 | @kbd{M-x load-library} differs from @kbd{M-x load-file} in that it | |
1197 | searches a sequence of directories and tries three file names in each | |
1198 | directory. Suppose your argument is @var{lib}; the three names are | |
1199 | @file{@var{lib}.elc}, @file{@var{lib}.el}, and lastly just | |
1200 | @file{@var{lib}}. If @file{@var{lib}.elc} exists, it is by convention | |
1201 | the result of compiling @file{@var{lib}.el}; it is better to load the | |
1202 | compiled file, since it will load and run faster. | |
1203 | ||
1204 | If @code{load-library} finds that @file{@var{lib}.el} is newer than | |
41f633c1 RS |
1205 | @file{@var{lib}.elc} file, it issues a warning, because it's likely |
1206 | that somebody made changes to the @file{.el} file and forgot to | |
1207 | recompile it. Nonetheless, it loads @file{@var{lib}.elc}. This is | |
1208 | because people often leave unfinished edits the source file, and don't | |
1209 | recompile it until they think it is ready to use. | |
6bf7aab6 DL |
1210 | |
1211 | Because the argument to @code{load-library} is usually not in itself | |
1212 | a valid file name, file name completion is not available. Indeed, when | |
1213 | using this command, you usually do not know exactly what file name | |
1214 | will be used. | |
1215 | ||
1216 | @vindex load-path | |
1217 | The sequence of directories searched by @kbd{M-x load-library} is | |
1218 | specified by the variable @code{load-path}, a list of strings that are | |
41f633c1 | 1219 | directory names. The default value of the list contains the directories where |
6bf7aab6 DL |
1220 | the Lisp code for Emacs itself is stored. If you have libraries of |
1221 | your own, put them in a single directory and add that directory | |
1222 | to @code{load-path}. @code{nil} in this list stands for the current default | |
1223 | directory, but it is probably not a good idea to put @code{nil} in the | |
1224 | list. If you find yourself wishing that @code{nil} were in the list, | |
1225 | most likely what you really want to do is use @kbd{M-x load-file} | |
1226 | this once. | |
1227 | ||
1228 | @cindex autoload | |
1229 | Often you do not have to give any command to load a library, because | |
1230 | the commands defined in the library are set up to @dfn{autoload} that | |
1231 | library. Trying to run any of those commands calls @code{load} to load | |
1232 | the library; this replaces the autoload definitions with the real ones | |
1233 | from the library. | |
1234 | ||
493c59e0 EZ |
1235 | @vindex load-dangerous-libraries |
1236 | @cindex Lisp files byte-compiled by XEmacs | |
a50c7a80 RS |
1237 | By default, Emacs refuses to load compiled Lisp files which were |
1238 | compiled with XEmacs, a modified versions of Emacs---they can cause | |
1239 | Emacs to crash. Set the variable @code{load-dangerous-libraries} to | |
1240 | @code{t} if you want to try loading them. | |
493c59e0 | 1241 | |
6bf7aab6 | 1242 | @node Lisp Eval |
dd525369 | 1243 | @section Evaluating Emacs Lisp Expressions |
6bf7aab6 DL |
1244 | @cindex Emacs-Lisp mode |
1245 | @cindex mode, Emacs-Lisp | |
1246 | ||
1247 | @findex emacs-lisp-mode | |
1248 | Lisp programs intended to be run in Emacs should be edited in | |
1249 | Emacs-Lisp mode; this happens automatically for file names ending in | |
1250 | @file{.el}. By contrast, Lisp mode itself is used for editing Lisp | |
1251 | programs intended for other Lisp systems. To switch to Emacs-Lisp mode | |
1252 | explicitly, use the command @kbd{M-x emacs-lisp-mode}. | |
1253 | ||
1254 | For testing of Lisp programs to run in Emacs, it is often useful to | |
1255 | evaluate part of the program as it is found in the Emacs buffer. For | |
1256 | example, after changing the text of a Lisp function definition, | |
1257 | evaluating the definition installs the change for future calls to the | |
1258 | function. Evaluation of Lisp expressions is also useful in any kind of | |
1259 | editing, for invoking noninteractive functions (functions that are | |
1260 | not commands). | |
1261 | ||
1262 | @table @kbd | |
1263 | @item M-: | |
1264 | Read a single Lisp expression in the minibuffer, evaluate it, and print | |
1265 | the value in the echo area (@code{eval-expression}). | |
1266 | @item C-x C-e | |
1267 | Evaluate the Lisp expression before point, and print the value in the | |
1268 | echo area (@code{eval-last-sexp}). | |
1269 | @item C-M-x | |
1270 | Evaluate the defun containing or after point, and print the value in | |
1271 | the echo area (@code{eval-defun}). | |
1272 | @item M-x eval-region | |
1273 | Evaluate all the Lisp expressions in the region. | |
4c242e96 | 1274 | @item M-x eval-buffer |
6bf7aab6 DL |
1275 | Evaluate all the Lisp expressions in the buffer. |
1276 | @end table | |
1277 | ||
09041c4b | 1278 | @ifinfo |
c668cdd0 EZ |
1279 | @c This uses ``colon'' instead of a literal `:' because Info cannot |
1280 | @c cope with a `:' in a menu | |
1281 | @kindex M-@key{colon} | |
09041c4b EZ |
1282 | @end ifinfo |
1283 | @ifnotinfo | |
1284 | @kindex M-: | |
1285 | @end ifnotinfo | |
6bf7aab6 DL |
1286 | @findex eval-expression |
1287 | @kbd{M-:} (@code{eval-expression}) is the most basic command for evaluating | |
1288 | a Lisp expression interactively. It reads the expression using the | |
1289 | minibuffer, so you can execute any expression on a buffer regardless of | |
1290 | what the buffer contains. When the expression is evaluated, the current | |
1291 | buffer is once again the buffer that was current when @kbd{M-:} was | |
1292 | typed. | |
1293 | ||
1294 | @kindex C-M-x @r{(Emacs-Lisp mode)} | |
1295 | @findex eval-defun | |
1296 | In Emacs-Lisp mode, the key @kbd{C-M-x} is bound to the command | |
1297 | @code{eval-defun}, which parses the defun containing or following point | |
1298 | as a Lisp expression and evaluates it. The value is printed in the echo | |
1299 | area. This command is convenient for installing in the Lisp environment | |
1300 | changes that you have just made in the text of a function definition. | |
1301 | ||
1302 | @kbd{C-M-x} treats @code{defvar} expressions specially. Normally, | |
1303 | evaluating a @code{defvar} expression does nothing if the variable it | |
1304 | defines already has a value. But @kbd{C-M-x} unconditionally resets the | |
1305 | variable to the initial value specified in the @code{defvar} expression. | |
9c8599ca | 1306 | @code{defcustom} expressions are treated similarly. |
6bf7aab6 | 1307 | This special feature is convenient for debugging Lisp programs. |
dc134342 JL |
1308 | Typing @kbd{C-M-x} on a @code{defface} expression reinitializes |
1309 | the face according to the @code{defface} specification. | |
6bf7aab6 DL |
1310 | |
1311 | @kindex C-x C-e | |
1312 | @findex eval-last-sexp | |
1313 | The command @kbd{C-x C-e} (@code{eval-last-sexp}) evaluates the Lisp | |
1314 | expression preceding point in the buffer, and displays the value in the | |
1315 | echo area. It is available in all major modes, not just Emacs-Lisp | |
1316 | mode. It does not treat @code{defvar} specially. | |
1317 | ||
ed4389af RS |
1318 | When the result of an evaluation is an integer, you can type |
1319 | @kbd{C-x C-e} a second time to display the value of the integer result | |
1320 | in additional formats (octal, hexadecimal, and character). | |
1321 | ||
c91809b2 RS |
1322 | If @kbd{C-x C-e}, or @kbd{M-:} is given a numeric argument, it |
1323 | inserts the value into the current buffer at point, rather than | |
1324 | displaying it in the echo area. The argument's value does not matter. | |
1325 | @kbd{C-M-x} with a numeric argument instruments the function | |
1326 | definition for Edebug (@pxref{Instrumenting, Instrumenting for Edebug,, elisp, the Emacs Lisp Reference Manual}). | |
6bf7aab6 DL |
1327 | |
1328 | @findex eval-region | |
4c242e96 | 1329 | @findex eval-buffer |
6bf7aab6 DL |
1330 | The most general command for evaluating Lisp expressions from a buffer |
1331 | is @code{eval-region}. @kbd{M-x eval-region} parses the text of the | |
1332 | region as one or more Lisp expressions, evaluating them one by one. | |
4c242e96 | 1333 | @kbd{M-x eval-buffer} is similar but evaluates the entire |
6bf7aab6 | 1334 | buffer. This is a reasonable way to install the contents of a file of |
58fa012d | 1335 | Lisp code that you are ready to test. Later, as you find bugs and |
6bf7aab6 DL |
1336 | change individual functions, use @kbd{C-M-x} on each function that you |
1337 | change. This keeps the Lisp world in step with the source file. | |
1338 | ||
9c8599ca DL |
1339 | @vindex eval-expression-print-level |
1340 | @vindex eval-expression-print-length | |
1341 | @vindex eval-expression-debug-on-error | |
444246ca | 1342 | The two customizable variables @code{eval-expression-print-level} and |
9c8599ca DL |
1343 | @code{eval-expression-print-length} control the maximum depth and length |
1344 | of lists to print in the result of the evaluation commands before | |
1345 | abbreviating them. @code{eval-expression-debug-on-error} controls | |
1346 | whether evaluation errors invoke the debugger when these commands are | |
41f633c1 | 1347 | used; its default is @code{t}. |
9c8599ca | 1348 | |
6bf7aab6 DL |
1349 | @node Lisp Interaction |
1350 | @section Lisp Interaction Buffers | |
1351 | ||
1352 | The buffer @samp{*scratch*} which is selected when Emacs starts up is | |
1353 | provided for evaluating Lisp expressions interactively inside Emacs. | |
1354 | ||
1355 | The simplest way to use the @samp{*scratch*} buffer is to insert Lisp | |
1356 | expressions and type @kbd{C-j} after each expression. This command | |
1357 | reads the Lisp expression before point, evaluates it, and inserts the | |
1358 | value in printed representation before point. The result is a complete | |
1359 | typescript of the expressions you have evaluated and their values. | |
1360 | ||
1361 | The @samp{*scratch*} buffer's major mode is Lisp Interaction mode, which | |
1362 | is the same as Emacs-Lisp mode except for the binding of @kbd{C-j}. | |
1363 | ||
1364 | @findex lisp-interaction-mode | |
1365 | The rationale for this feature is that Emacs must have a buffer when | |
1366 | it starts up, but that buffer is not useful for editing files since a | |
1367 | new buffer is made for every file that you visit. The Lisp interpreter | |
1368 | typescript is the most useful thing I can think of for the initial | |
1369 | buffer to do. Type @kbd{M-x lisp-interaction-mode} to put the current | |
1370 | buffer in Lisp Interaction mode. | |
1371 | ||
1372 | @findex ielm | |
1373 | An alternative way of evaluating Emacs Lisp expressions interactively | |
1374 | is to use Inferior Emacs-Lisp mode, which provides an interface rather | |
1375 | like Shell mode (@pxref{Shell Mode}) for evaluating Emacs Lisp | |
1376 | expressions. Type @kbd{M-x ielm} to create an @samp{*ielm*} buffer | |
b9195b52 RS |
1377 | which uses this mode. For more information see that command's |
1378 | documentation. | |
6bf7aab6 DL |
1379 | |
1380 | @node External Lisp | |
1381 | @section Running an External Lisp | |
1382 | ||
1383 | Emacs has facilities for running programs in other Lisp systems. You can | |
1384 | run a Lisp process as an inferior of Emacs, and pass expressions to it to | |
1385 | be evaluated. You can also pass changed function definitions directly from | |
1386 | the Emacs buffers in which you edit the Lisp programs to the inferior Lisp | |
1387 | process. | |
1388 | ||
1389 | @findex run-lisp | |
1390 | @vindex inferior-lisp-program | |
1391 | @kindex C-x C-z | |
1392 | To run an inferior Lisp process, type @kbd{M-x run-lisp}. This runs | |
1393 | the program named @code{lisp}, the same program you would run by typing | |
1394 | @code{lisp} as a shell command, with both input and output going through | |
1395 | an Emacs buffer named @samp{*lisp*}. That is to say, any ``terminal | |
1396 | output'' from Lisp will go into the buffer, advancing point, and any | |
1397 | ``terminal input'' for Lisp comes from text in the buffer. (You can | |
1398 | change the name of the Lisp executable file by setting the variable | |
1399 | @code{inferior-lisp-program}.) | |
1400 | ||
1401 | To give input to Lisp, go to the end of the buffer and type the input, | |
1402 | terminated by @key{RET}. The @samp{*lisp*} buffer is in Inferior Lisp | |
1403 | mode, which combines the special characteristics of Lisp mode with most | |
1404 | of the features of Shell mode (@pxref{Shell Mode}). The definition of | |
1405 | @key{RET} to send a line to a subprocess is one of the features of Shell | |
1406 | mode. | |
1407 | ||
1408 | @findex lisp-mode | |
1409 | For the source files of programs to run in external Lisps, use Lisp | |
41f633c1 RS |
1410 | mode. You can switch to this mode with @kbd{M-x lisp-mode}, and it is |
1411 | used automatically for files whose names end in @file{.l}, | |
1412 | @file{.lsp}, or @file{.lisp}. | |
6bf7aab6 DL |
1413 | |
1414 | @kindex C-M-x @r{(Lisp mode)} | |
1415 | @findex lisp-eval-defun | |
1416 | When you edit a function in a Lisp program you are running, the easiest | |
1417 | way to send the changed definition to the inferior Lisp process is the key | |
1418 | @kbd{C-M-x}. In Lisp mode, this runs the function @code{lisp-eval-defun}, | |
1419 | which finds the defun around or following point and sends it as input to | |
1420 | the Lisp process. (Emacs can send input to any inferior process regardless | |
1421 | of what buffer is current.) | |
1422 | ||
41f633c1 RS |
1423 | Contrast the meanings of @kbd{C-M-x} in Lisp mode (for editing |
1424 | programs to be run in another Lisp system) and Emacs-Lisp mode (for | |
1425 | editing Lisp programs to be run in Emacs; see @pxref{Lisp Eval}): in | |
1426 | both modes it has the effect of installing the function definition | |
1427 | that point is in, but the way of doing so is different according to | |
1428 | where the relevant Lisp environment is found. | |
1429 | ||
ab5796a9 MB |
1430 | |
1431 | @ignore | |
1432 | arch-tag: 9c3c2f71-b332-4144-8500-3ff9945a50ed | |
1433 | @end ignore |