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1 | @c This is part of the Emacs manual. |
2 | @c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001, | |
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3 | @c 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 |
4 | @c Free Software Foundation, Inc. | |
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5 | @c See file emacs.texi for copying conditions. |
6 | @node Building, Maintaining, Programs, Top | |
7 | @chapter Compiling and Testing Programs | |
8 | @cindex building programs | |
9 | @cindex program building | |
10 | @cindex running Lisp functions | |
11 | ||
12 | The previous chapter discusses the Emacs commands that are useful for | |
13 | making changes in programs. This chapter deals with commands that assist | |
14 | in the larger process of compiling and testing programs. | |
15 | ||
16 | @menu | |
17 | * Compilation:: Compiling programs in languages other | |
18 | than Lisp (C, Pascal, etc.). | |
19 | * Compilation Mode:: The mode for visiting compiler errors. | |
20 | * Compilation Shell:: Customizing your shell properly | |
21 | for use in the compilation buffer. | |
22 | * Grep Searching:: Searching with grep. | |
23 | * Flymake:: Finding syntax errors on the fly. | |
8838673e | 24 | * Debuggers:: Running symbolic debuggers for non-Lisp programs. |
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25 | * Executing Lisp:: Various modes for editing Lisp programs, |
26 | with different facilities for running | |
27 | the Lisp programs. | |
28 | * Libraries: Lisp Libraries. Creating Lisp programs to run in Emacs. | |
29 | * Eval: Lisp Eval. Executing a single Lisp expression in Emacs. | |
30 | * Interaction: Lisp Interaction. Executing Lisp in an Emacs buffer. | |
8838673e | 31 | * External Lisp:: Communicating through Emacs with a separate Lisp. |
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32 | @end menu |
33 | ||
34 | @node Compilation | |
35 | @section Running Compilations under Emacs | |
36 | @cindex inferior process | |
37 | @cindex make | |
38 | @cindex compilation errors | |
39 | @cindex error log | |
40 | ||
41 | Emacs can run compilers for noninteractive languages such as C and | |
42 | Fortran as inferior processes, feeding the error log into an Emacs buffer. | |
43 | It can also parse the error messages and show you the source lines where | |
44 | compilation errors occurred. | |
45 | ||
46 | @table @kbd | |
47 | @item M-x compile | |
48 | Run a compiler asynchronously under Emacs, with error messages going to | |
49 | the @samp{*compilation*} buffer. | |
50 | @item M-x recompile | |
51 | Invoke a compiler with the same command as in the last invocation of | |
52 | @kbd{M-x compile}. | |
53 | @item M-x kill-compilation | |
54 | Kill the running compilation subprocess. | |
55 | @end table | |
56 | ||
57 | @findex compile | |
58 | To run @code{make} or another compilation command, do @kbd{M-x | |
59 | compile}. This command reads a shell command line using the minibuffer, | |
60 | and then executes the command in an inferior shell, putting output in | |
61 | the buffer named @samp{*compilation*}. The current buffer's default | |
62 | directory is used as the working directory for the execution of the | |
63 | command; normally, therefore, the compilation happens in this | |
64 | directory. | |
65 | ||
66 | @vindex compile-command | |
67 | The default for the compilation command is normally @samp{make -k}, | |
68 | which is correct most of the time for nontrivial programs. | |
a03334ca | 69 | @xref{Top,, Make, make, GNU Make Manual}. If you have done @kbd{M-x |
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70 | compile} before, the default each time is the command you used the |
71 | previous time. @code{compile} stores this command in the variable | |
72 | @code{compile-command}, so setting that variable specifies the default | |
73 | for the next use of @kbd{M-x compile}. If a file specifies a file | |
74 | local value for @code{compile-command}, that provides the default when | |
75 | you type @kbd{M-x compile} in that file's buffer. @xref{File | |
76 | Variables}. | |
77 | ||
78 | Starting a compilation displays the buffer @samp{*compilation*} in | |
79 | another window but does not select it. The buffer's mode line tells | |
80 | you whether compilation is finished, with the word @samp{run}, | |
81 | @samp{signal} or @samp{exit} inside the parentheses. You do not have | |
82 | to keep this buffer visible; compilation continues in any case. While | |
83 | a compilation is going on, the string @samp{Compiling} appears in the | |
84 | mode lines of all windows. When this string disappears, the | |
85 | compilation is finished. | |
86 | ||
87 | If you want to watch the compilation transcript as it appears, switch | |
88 | to the @samp{*compilation*} buffer and move point to the end of the | |
89 | buffer. When point is at the end, new compilation output is inserted | |
90 | above point, which remains at the end. If point is not at the end of | |
91 | the buffer, it remains fixed while more compilation output is added at | |
92 | the end of the buffer. | |
93 | ||
94 | @cindex compilation buffer, keeping point at end | |
95 | @vindex compilation-scroll-output | |
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96 | If you change the variable @code{compilation-scroll-output} to a |
97 | non-@code{nil} value, the compilation buffer will scroll automatically | |
98 | to follow the output as it comes in. If the value is | |
99 | @code{first-error}, the scrolling stops at the first error that | |
100 | appears, leaving point at that error. For any other non-@code{nil} | |
101 | value, the buffer continues scrolling until there is no more output. | |
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102 | |
103 | @findex recompile | |
104 | To rerun the last compilation with the same command, type @kbd{M-x | |
105 | recompile}. This automatically reuses the compilation command from | |
106 | the last invocation of @kbd{M-x compile}. It also reuses the | |
107 | @samp{*compilation*} buffer and starts the compilation in its default | |
108 | directory, which is the directory in which the previous compilation | |
109 | was started. | |
110 | ||
111 | When the compiler process terminates, for whatever reason, the mode | |
112 | line of the @samp{*compilation*} buffer changes to say @samp{exit} | |
113 | (followed by the exit code, @samp{[0]} for a normal exit), or | |
114 | @samp{signal} (if a signal terminated the process), instead of | |
115 | @samp{run}. | |
116 | ||
117 | @findex kill-compilation | |
118 | Starting a new compilation also kills any compilation already | |
119 | running in @samp{*compilation*}, as the buffer can only handle one | |
120 | compilation at any time. However, @kbd{M-x compile} asks for | |
121 | confirmation before actually killing a compilation that is running. | |
122 | You can also kill the compilation process with @kbd{M-x | |
123 | kill-compilation}. | |
124 | ||
125 | If you want to run two compilations at once, you should start the | |
126 | first one, then rename the @samp{*compilation*} buffer (perhaps using | |
127 | @code{rename-uniquely}; @pxref{Misc Buffer}), and start the other | |
128 | compilation. That will create a new @samp{*compilation*} buffer. | |
129 | ||
130 | Emacs does not expect a compiler process to launch asynchronous | |
131 | subprocesses; if it does, and they keep running after the main | |
132 | compiler process has terminated, Emacs may kill them or their output | |
133 | may not arrive in Emacs. To avoid this problem, make the main process | |
134 | wait for its subprocesses to finish. In a shell script, you can do this | |
135 | using @samp{$!} and @samp{wait}, like this: | |
136 | ||
137 | @example | |
138 | (sleep 10; echo 2nd)& pid=$! # @r{Record pid of subprocess} | |
139 | echo first message | |
140 | wait $pid # @r{Wait for subprocess} | |
141 | @end example | |
142 | ||
143 | If the background process does not output to the compilation buffer, | |
144 | so you only need to prevent it from being killed when the main | |
145 | compilation process terminates, this is sufficient: | |
146 | ||
147 | @example | |
148 | nohup @var{command}; sleep 1 | |
149 | @end example | |
150 | ||
151 | @vindex compilation-environment | |
152 | You can control the environment passed to the compilation command | |
153 | with the variable @code{compilation-environment}. Its value is a list | |
154 | of environment variable settings; each element should be a string of | |
155 | the form @code{"@var{envvarname}=@var{value}"}. These environment | |
156 | variable settings override the usual ones. | |
157 | ||
158 | @node Compilation Mode | |
159 | @section Compilation Mode | |
160 | ||
161 | @cindex Compilation mode | |
162 | @cindex mode, Compilation | |
163 | The @samp{*compilation*} buffer uses a special major mode, | |
164 | Compilation mode, whose main feature is to provide a convenient way to | |
165 | visit the source line corresponding to an error message. These | |
166 | commands are also available in other special buffers that list | |
167 | locations in files, including those made by @kbd{M-x grep} and | |
168 | @kbd{M-x occur}. | |
169 | ||
170 | @table @kbd | |
171 | @item M-g M-n | |
172 | @itemx M-g n | |
173 | @itemx C-x ` | |
174 | Visit the locus of the next error message or match. | |
175 | @item M-g M-p | |
176 | @itemx M-g p | |
177 | Visit the locus of the previous error message or match. | |
178 | @item @key{RET} | |
179 | Visit the locus of the error message that point is on. | |
180 | This command is used in the compilation buffer. | |
181 | @item Mouse-2 | |
182 | Visit the locus of the error message that you click on. | |
183 | @item M-n | |
184 | Find and highlight the locus of the next error message, without | |
185 | selecting the source buffer. | |
186 | @item M-p | |
187 | Find and highlight the locus of the previous error message, without | |
188 | selecting the source buffer. | |
189 | @item M-@} | |
190 | Move point to the next error for a different file than the current | |
191 | one. | |
192 | @item M-@{ | |
193 | Move point to the previous error for a different file than the current | |
194 | one. | |
195 | @item C-c C-f | |
196 | Toggle Next Error Follow minor mode, which makes cursor motion in the | |
197 | compilation buffer produce automatic source display. | |
198 | @end table | |
199 | ||
200 | @findex compile-goto-error | |
a03334ca | 201 | @vindex compilation-auto-jump-to-first-error |
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202 | You can visit the source for any particular error message by moving |
203 | point in the @samp{*compilation*} buffer to that error message and | |
204 | typing @key{RET} (@code{compile-goto-error}). Alternatively, you can | |
205 | click @kbd{Mouse-2} on the error message; you need not switch to the | |
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206 | @samp{*compilation*} buffer first. If you set the variable |
207 | @code{compilation-auto-jump-to-first-error} to a non-@code{nil} value, | |
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208 | Emacs automatically jumps to the first error, if any, as soon as it |
209 | appears in the @samp{*compilation*} buffer. | |
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210 | |
211 | @kindex M-g M-n | |
212 | @kindex M-g n | |
213 | @kindex C-x ` | |
214 | @findex next-error | |
215 | @vindex next-error-highlight | |
216 | To parse the compiler error messages sequentially, type @kbd{C-x `} | |
217 | (@code{next-error}). The character following the @kbd{C-x} is the | |
218 | backquote or ``grave accent,'' not the single-quote. This command is | |
219 | available in all buffers, not just in @samp{*compilation*}; it | |
220 | displays the next error message at the top of one window and source | |
221 | location of the error in another window. It also temporarily | |
222 | highlights the relevant source line, for a period controlled by the | |
223 | variable @code{next-error-highlight}. | |
224 | ||
225 | The first time @w{@kbd{C-x `}} is used after the start of a compilation, | |
226 | it moves to the first error's location. Subsequent uses of @kbd{C-x | |
227 | `} advance down to subsequent errors. If you visit a specific error | |
228 | message with @key{RET} or @kbd{Mouse-2}, subsequent @w{@kbd{C-x `}} | |
229 | commands advance from there. When @w{@kbd{C-x `}} gets to the end of the | |
230 | buffer and finds no more error messages to visit, it fails and signals | |
231 | an Emacs error. @w{@kbd{C-u C-x `}} starts scanning from the beginning of | |
232 | the compilation buffer, and goes to the first error's location. | |
233 | ||
234 | @vindex compilation-skip-threshold | |
235 | By default, @w{@kbd{C-x `}} skips less important messages. The variable | |
236 | @code{compilation-skip-threshold} controls this. If its value is 2, | |
237 | @w{@kbd{C-x `}} skips anything less than error, 1 skips anything less | |
238 | than warning, and 0 doesn't skip any messages. The default is 1. | |
239 | ||
240 | When the window has a left fringe, an arrow in the fringe points to | |
241 | the current message in the compilation buffer. The variable | |
242 | @code{compilation-context-lines} controls the number of lines of | |
243 | leading context to display before the current message. Going to an | |
244 | error message location scrolls the @samp{*compilation*} buffer to put | |
245 | the message that far down from the top. The value @code{nil} is | |
246 | special: if there's a left fringe, the window doesn't scroll at all | |
247 | if the message is already visible. If there is no left fringe, | |
248 | @code{nil} means display the message at the top of the window. | |
249 | ||
250 | If you're not in the compilation buffer when you run | |
251 | @code{next-error}, Emacs will look for a buffer that contains error | |
252 | messages. First, it looks for one displayed in the selected frame, | |
253 | then for one that previously had @code{next-error} called on it, and | |
254 | then at the current buffer. Finally, Emacs looks at all the remaining | |
255 | buffers. @code{next-error} signals an error if it can't find any such | |
256 | buffer. | |
257 | ||
258 | @vindex compilation-error-regexp-alist | |
259 | @vindex grep-regexp-alist | |
260 | To parse messages from the compiler, Compilation mode uses the | |
261 | variable @code{compilation-error-regexp-alist} which lists various | |
262 | formats of error messages and tells Emacs how to extract the source file | |
263 | and the line number from the text of a message. If your compiler isn't | |
264 | supported, you can tailor Compilation mode to it by adding elements to | |
265 | that list. A similar variable @code{grep-regexp-alist} tells Emacs how | |
266 | to parse output of a @code{grep} command. | |
267 | ||
268 | @findex compilation-next-error | |
269 | @findex compilation-previous-error | |
270 | @findex compilation-next-file | |
271 | @findex compilation-previous-file | |
272 | Compilation mode also redefines the keys @key{SPC} and @key{DEL} to | |
273 | scroll by screenfuls, and @kbd{M-n} (@code{compilation-next-error}) | |
274 | and @kbd{M-p} (@code{compilation-previous-error}) to move to the next | |
275 | or previous error message. You can also use @kbd{M-@{} | |
276 | (@code{compilation-next-file} and @kbd{M-@}} | |
277 | (@code{compilation-previous-file}) to move up or down to an error | |
278 | message for a different source file. | |
279 | ||
280 | @cindex Next Error Follow mode | |
281 | @findex next-error-follow-minor-mode | |
282 | You can type @kbd{C-c C-f} to toggle Next Error Follow mode. In | |
283 | this minor mode, ordinary cursor motion in the compilation buffer | |
284 | automatically updates the source buffer. For instance, moving the | |
285 | cursor to the next error message causes the location of that error to | |
286 | be displayed immediately. | |
287 | ||
288 | The features of Compilation mode are also available in a minor mode | |
289 | called Compilation Minor mode. This lets you parse error messages in | |
290 | any buffer, not just a normal compilation output buffer. Type @kbd{M-x | |
291 | compilation-minor-mode} to enable the minor mode. This defines the keys | |
292 | @key{RET} and @kbd{Mouse-2}, as in the Compilation major mode. | |
293 | ||
294 | Compilation minor mode works in any buffer, as long as the contents | |
295 | are in a format that it understands. In an Rlogin buffer (@pxref{Remote | |
296 | Host}), Compilation minor mode automatically accesses remote source | |
297 | files by FTP (@pxref{File Names}). | |
298 | ||
299 | @node Compilation Shell | |
300 | @section Subshells for Compilation | |
301 | ||
302 | Emacs uses a shell to run the compilation command, but specifies the | |
303 | option for a noninteractive shell. This means, in particular, that | |
304 | the shell should start with no prompt. If you find your usual shell | |
305 | prompt making an unsightly appearance in the @samp{*compilation*} | |
306 | buffer, it means you have made a mistake in your shell's init file by | |
307 | setting the prompt unconditionally. (This init file's name may be | |
308 | @file{.bashrc}, @file{.profile}, @file{.cshrc}, @file{.shrc}, or | |
309 | various other things, depending on the shell you use.) The shell init | |
310 | file should set the prompt only if there already is a prompt. Here's | |
311 | how to do it in bash: | |
312 | ||
313 | @example | |
314 | if [ "$@{PS1+set@}" = set ] | |
315 | then PS1=@dots{} | |
316 | fi | |
317 | @end example | |
318 | ||
319 | @noindent | |
320 | And here's how to do it in csh: | |
321 | ||
322 | @example | |
323 | if ($?prompt) set prompt = @dots{} | |
324 | @end example | |
325 | ||
326 | There may well be other things that your shell's init file | |
327 | ought to do only for an interactive shell. You can use the same | |
328 | method to conditionalize them. | |
329 | ||
330 | The MS-DOS ``operating system'' does not support asynchronous | |
331 | subprocesses; to work around this lack, @kbd{M-x compile} runs the | |
332 | compilation command synchronously on MS-DOS. As a consequence, you must | |
333 | wait until the command finishes before you can do anything else in | |
334 | Emacs. | |
335 | @iftex | |
336 | @inforef{MS-DOS,,emacs-xtra}. | |
337 | @end iftex | |
338 | @ifnottex | |
339 | @xref{MS-DOS}. | |
340 | @end ifnottex | |
341 | ||
342 | @node Grep Searching | |
343 | @section Searching with Grep under Emacs | |
344 | ||
345 | Just as you can run a compiler from Emacs and then visit the lines | |
346 | with compilation errors, you can also run @code{grep} and then visit | |
347 | the lines on which matches were found. This works by treating the | |
348 | matches reported by @code{grep} as if they were ``errors.'' The | |
349 | buffer of matches uses Grep mode, which is a variant of Compilation | |
350 | mode (@pxref{Compilation Mode}). | |
351 | ||
352 | @table @kbd | |
353 | @item M-x grep | |
467e8d77 | 354 | @itemx M-x lgrep |
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355 | Run @code{grep} asynchronously under Emacs, with matching lines |
356 | listed in the buffer named @samp{*grep*}. | |
357 | @item M-x grep-find | |
358 | @itemx M-x find-grep | |
359 | @itemx M-x rgrep | |
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360 | Run @code{grep} via @code{find}, and collect output in the buffer |
361 | named @samp{*grep*}. | |
362 | @item M-x zrgrep | |
363 | Run @code{zgrep} and collect output in the buffer named @samp{*grep*}. | |
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364 | @item M-x kill-grep |
365 | Kill the running @code{grep} subprocess. | |
366 | @end table | |
367 | ||
368 | @findex grep | |
369 | To run @code{grep}, type @kbd{M-x grep}, then enter a command line | |
370 | that specifies how to run @code{grep}. Use the same arguments you | |
371 | would give @code{grep} when running it normally: a @code{grep}-style | |
372 | regexp (usually in single-quotes to quote the shell's special | |
373 | characters) followed by file names, which may use wildcards. If you | |
374 | specify a prefix argument for @kbd{M-x grep}, it finds the tag | |
375 | (@pxref{Tags}) in the buffer around point, and puts that into the | |
376 | default @code{grep} command. | |
377 | ||
378 | Your command need not simply run @code{grep}; you can use any shell | |
379 | command that produces output in the same format. For instance, you | |
380 | can chain @code{grep} commands, like this: | |
381 | ||
382 | @example | |
383 | grep -nH -e foo *.el | grep bar | grep toto | |
384 | @end example | |
385 | ||
386 | The output from @code{grep} goes in the @samp{*grep*} buffer. You | |
387 | can find the corresponding lines in the original files using @w{@kbd{C-x | |
388 | `}}, @key{RET}, and so forth, just like compilation errors. | |
389 | ||
390 | Some grep programs accept a @samp{--color} option to output special | |
391 | markers around matches for the purpose of highlighting. You can make | |
392 | use of this feature by setting @code{grep-highlight-matches} to | |
393 | @code{t}. When displaying a match in the source buffer, the exact | |
394 | match will be highlighted, instead of the entire source line. | |
395 | ||
396 | @findex grep-find | |
397 | @findex find-grep | |
398 | The command @kbd{M-x grep-find} (also available as @kbd{M-x | |
399 | find-grep}) is similar to @kbd{M-x grep}, but it supplies a different | |
400 | initial default for the command---one that runs both @code{find} and | |
401 | @code{grep}, so as to search every file in a directory tree. See also | |
402 | the @code{find-grep-dired} command, in @ref{Dired and Find}. | |
403 | ||
404 | @findex lgrep | |
405 | @findex rgrep | |
26e533e2 | 406 | @findex zrgrep |
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407 | The commands @kbd{M-x lgrep} (local grep) and @kbd{M-x rgrep} |
408 | (recursive grep) are more user-friendly versions of @code{grep} and | |
409 | @code{grep-find}, which prompt separately for the regular expression | |
410 | to match, the files to search, and the base directory for the search. | |
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411 | Case sensitivity of the search is controlled by the current value of |
412 | @code{case-fold-search}. The command @kbd{M-x zrgrep} is similar to | |
413 | @code{rgrep}, but it calls @code{zgrep} instead of @code{grep} to | |
414 | search the contents of gzipped files. | |
8cf51b2c | 415 | |
26e533e2 | 416 | These commands build the shell commands based on the variables |
8cf51b2c | 417 | @code{grep-template} (for @code{lgrep}) and @code{grep-find-template} |
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418 | (for @code{rgrep}). The files to search can use aliases defined in |
419 | the variable @code{grep-files-aliases}. | |
8cf51b2c | 420 | |
26e533e2 | 421 | Subdirectories listed in the variable |
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422 | @code{grep-find-ignored-directories} such as those typically used by |
423 | various version control systems, like CVS and arch, are automatically | |
424 | skipped by @code{rgrep}. | |
425 | ||
426 | @node Flymake | |
427 | @section Finding Syntax Errors On The Fly | |
428 | @cindex checking syntax | |
429 | ||
430 | Flymake mode is a minor mode that performs on-the-fly syntax | |
431 | checking for many programming and markup languages, including C, C++, | |
432 | Perl, HTML, and @TeX{}/La@TeX{}. It is somewhat analogous to Flyspell | |
433 | mode, which performs spell checking for ordinary human languages in a | |
434 | similar fashion (@pxref{Spelling}). As you edit a file, Flymake mode | |
435 | runs an appropriate syntax checking tool in the background, using a | |
436 | temporary copy of the buffer. It then parses the error and warning | |
437 | messages, and highlights the erroneous lines in the buffer. The | |
438 | syntax checking tool used depends on the language; for example, for | |
439 | C/C++ files this is usually the C compiler. Flymake can also use | |
440 | build tools such as @code{make} for checking complicated projects. | |
441 | ||
442 | To activate Flymake mode, type @kbd{M-x flymake-mode}. You can move | |
443 | to the errors spotted by Flymake mode with @kbd{M-x | |
444 | flymake-goto-next-error} and @kbd{M-x flymake-goto-prev-error}. To | |
445 | display any error messages associated with the current line, use | |
446 | @kbd{M-x flymake-display-err-menu-for-current-line}. | |
447 | ||
448 | For more details about using Flymake, see @ref{Top, Flymake, | |
449 | Flymake, flymake, The Flymake Manual}. | |
450 | ||
451 | @node Debuggers | |
452 | @section Running Debuggers Under Emacs | |
453 | @cindex debuggers | |
454 | @cindex GUD library | |
455 | @cindex GDB | |
456 | @cindex DBX | |
457 | @cindex SDB | |
458 | @cindex XDB | |
459 | @cindex Perldb | |
460 | @cindex JDB | |
461 | @cindex PDB | |
462 | ||
463 | @c Do you believe in GUD? | |
a03334ca CY |
464 | The GUD (Grand Unified Debugger) library provides an Emacs interface |
465 | to a wide variety of symbolic debuggers. Unlike the GDB graphical | |
466 | interface, which only runs GDB (@pxref{GDB Graphical Interface}), GUD | |
467 | can also run DBX, SDB, XDB, Perl's debugging mode, the Python debugger | |
468 | PDB, or the Java Debugger JDB. | |
8cf51b2c | 469 | |
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470 | In addition, Emacs contains a built-in system for debugging Emacs |
471 | Lisp programs. @xref{Debugging,, The Lisp Debugger, elisp, the Emacs | |
472 | Lisp Reference Manual}, for information on the Emacs Lisp debugger. | |
473 | ||
8cf51b2c | 474 | @menu |
8838673e GM |
475 | * Starting GUD:: How to start a debugger subprocess. |
476 | * Debugger Operation:: Connection between the debugger and source buffers. | |
477 | * Commands of GUD:: Key bindings for common commands. | |
478 | * GUD Customization:: Defining your own commands for GUD. | |
b424697f NR |
479 | * GDB Graphical Interface:: An enhanced mode that uses GDB features to |
480 | implement a graphical debugging environment through | |
481 | Emacs. | |
8cf51b2c GM |
482 | @end menu |
483 | ||
484 | @node Starting GUD | |
b424697f | 485 | @subsection Starting GUD |
8cf51b2c | 486 | |
a03334ca CY |
487 | There are several commands for starting a debugger under GUD, each |
488 | corresponding to a particular debugger program. | |
8cf51b2c GM |
489 | |
490 | @table @kbd | |
b424697f NR |
491 | @item M-x gdb @key{RET} @var{file} @key{RET} |
492 | @findex gdb | |
493 | Run GDB as a subprocess of Emacs. This uses an IDE-like graphical | |
494 | interface; see @ref{GDB Graphical Interface}. Only GDB works with the | |
495 | graphical interface. | |
496 | ||
4f45c619 NR |
497 | @item M-x gud-gdb @key{RET} @var{file} @key{RET} |
498 | @findex gud-gdb | |
499 | Run GDB as a subprocess of Emacs. This command creates a buffer for | |
500 | input and output to GDB, and switches to it. If a GDB buffer already | |
b424697f | 501 | exists, it just switches to that buffer. |
8cf51b2c GM |
502 | |
503 | @item M-x dbx @key{RET} @var{file} @key{RET} | |
504 | @findex dbx | |
b424697f NR |
505 | Run DBX as a subprocess of Emacs. Since Emacs does not implement a |
506 | graphical interface for DBX, communication with DBX works by typing | |
507 | commands in the GUD interaction buffer. The same is true for all | |
508 | the other supported debuggers. | |
8cf51b2c GM |
509 | |
510 | @item M-x xdb @key{RET} @var{file} @key{RET} | |
511 | @findex xdb | |
512 | @vindex gud-xdb-directories | |
a03334ca | 513 | Run XDB as a subprocess of Emacs. Use the variable |
8cf51b2c GM |
514 | @code{gud-xdb-directories} to specify directories to search for source |
515 | files. | |
516 | ||
517 | @item M-x sdb @key{RET} @var{file} @key{RET} | |
518 | @findex sdb | |
a03334ca | 519 | Run SDB as a subprocess of Emacs. |
8cf51b2c | 520 | |
a03334ca | 521 | Some versions of SDB do not mention source file names in their |
8cf51b2c GM |
522 | messages. When you use them, you need to have a valid tags table |
523 | (@pxref{Tags}) in order for GUD to find functions in the source code. | |
a03334ca CY |
524 | If you have not visited a tags table or the tags table doesn't list |
525 | one of the functions, you get a message saying @samp{The sdb support | |
526 | requires a valid tags table to work}. If this happens, generate a | |
527 | valid tags table in the working directory and try again. | |
8cf51b2c GM |
528 | |
529 | @item M-x perldb @key{RET} @var{file} @key{RET} | |
530 | @findex perldb | |
531 | Run the Perl interpreter in debug mode to debug @var{file}, a Perl program. | |
532 | ||
533 | @item M-x jdb @key{RET} @var{file} @key{RET} | |
534 | @findex jdb | |
535 | Run the Java debugger to debug @var{file}. | |
536 | ||
537 | @item M-x pdb @key{RET} @var{file} @key{RET} | |
538 | @findex pdb | |
539 | Run the Python debugger to debug @var{file}. | |
540 | @end table | |
541 | ||
542 | Each of these commands takes one argument: a command line to invoke | |
543 | the debugger. In the simplest case, specify just the name of the | |
544 | executable file you want to debug. You may also use options that the | |
545 | debugger supports. However, shell wildcards and variables are not | |
546 | allowed. GUD assumes that the first argument not starting with a | |
547 | @samp{-} is the executable file name. | |
548 | ||
a03334ca | 549 | @cindex remote host, debugging on |
7af517e7 EZ |
550 | Tramp provides a facility to debug programs on remote hosts |
551 | (@pxref{Running a debugger on a remote host, Running a debugger on a | |
552 | remote host,, tramp, The Tramp Manual}), whereby both the debugger and | |
553 | the program being debugged are on the same remote host. This should | |
554 | not be confused with debugging programs remotely, where the program | |
555 | and the debugger run on different machines, as can be done using the | |
556 | GDB remote debugging feature, for example (@pxref{Remote Debugging,, | |
557 | Debugging Remote Programs, gdb, The GNU debugger}). | |
8cf51b2c GM |
558 | |
559 | @node Debugger Operation | |
b424697f | 560 | @subsection Debugger Operation |
8cf51b2c GM |
561 | |
562 | @cindex fringes, and current execution line in GUD | |
563 | Generally when you run a debugger with GUD, the debugger uses an Emacs | |
564 | buffer for its ordinary input and output. This is called the GUD | |
565 | buffer. Input and output from the program you are debugging also use | |
566 | this buffer. We call this @dfn{text command mode}. The GDB Graphical | |
567 | Interface can use further buffers (@pxref{GDB Graphical Interface}). | |
568 | ||
569 | The debugger displays the source files of the program by visiting | |
570 | them in Emacs buffers. An arrow in the left fringe indicates the | |
571 | current execution line.@footnote{On a text-only terminal, the arrow | |
572 | appears as @samp{=>} and overlays the first two text columns.} Moving | |
573 | point in this buffer does not move the arrow. The arrow is not part | |
574 | of the file's text; it appears only on the screen. | |
575 | ||
576 | You can start editing these source files at any time in the buffers | |
577 | that display them. If you do modify a source file, keep in mind that | |
578 | inserting or deleting lines will throw off the arrow's positioning; | |
579 | GUD has no way of figuring out which line corresponded before your | |
580 | changes to the line number in a debugger message. Also, you'll | |
581 | typically have to recompile and restart the program for your changes | |
582 | to be reflected in the debugger's tables. | |
583 | ||
584 | @cindex tooltips with GUD | |
585 | @vindex tooltip-gud-modes | |
586 | @vindex gud-tooltip-mode | |
587 | @vindex gud-tooltip-echo-area | |
588 | The Tooltip facility (@pxref{Tooltips}) provides support for GUD@. | |
589 | You activate this feature by turning on the minor mode | |
590 | @code{gud-tooltip-mode}. Then you can display a variable's value in a | |
591 | tooltip simply by pointing at it with the mouse. This operates in the | |
592 | GUD buffer and in source buffers with major modes in the list | |
593 | @code{gud-tooltip-modes}. If the variable @code{gud-tooltip-echo-area} | |
594 | is non-@code{nil} then the variable's value is displayed in the echo | |
595 | area. When debugging a C program using the GDB Graphical Interface, you | |
596 | can also display macro definitions associated with an identifier when | |
597 | the program is not executing. | |
598 | ||
599 | GUD tooltips are disabled when you use GDB in text command mode | |
600 | (@pxref{GDB Graphical Interface}), because displaying an expression's | |
601 | value in GDB can sometimes expand a macro and result in a side effect | |
602 | that interferes with the program's operation. The GDB graphical | |
603 | interface supports GUD tooltips and assures they will not cause side | |
604 | effects. | |
605 | ||
606 | @node Commands of GUD | |
b424697f | 607 | @subsection Commands of GUD |
8cf51b2c GM |
608 | |
609 | The GUD interaction buffer uses a variant of Shell mode, so the | |
610 | Emacs commands of Shell mode are available (@pxref{Shell Mode}). All | |
611 | the usual commands for your debugger are available, and you can use | |
612 | the Shell mode history commands to repeat them. If you wish, you can | |
613 | control your debugger process entirely through this buffer. | |
614 | ||
615 | GUD mode also provides commands for setting and clearing | |
616 | breakpoints, for selecting stack frames, and for stepping through the | |
617 | program. These commands are available both in the GUD buffer and | |
618 | globally, but with different key bindings. It also has its own tool | |
619 | bar from which you can invoke the more common commands by clicking on | |
620 | the appropriate icon. This is particularly useful for repetitive | |
621 | commands like @code{gud-next} and @code{gud-step}, and allows you to | |
622 | keep the GUD buffer hidden. | |
623 | ||
624 | The breakpoint commands are normally used in source file buffers, | |
625 | because that is the easiest way to specify where to set or clear the | |
626 | breakpoint. Here's the global command to set a breakpoint: | |
627 | ||
628 | @table @kbd | |
629 | @item C-x @key{SPC} | |
630 | @kindex C-x SPC | |
631 | Set a breakpoint on the source line that point is on. | |
632 | @end table | |
633 | ||
634 | @kindex C-x C-a @r{(GUD)} | |
635 | Here are the other special commands provided by GUD@. The keys | |
636 | starting with @kbd{C-c} are available only in the GUD interaction | |
637 | buffer. The key bindings that start with @kbd{C-x C-a} are available | |
638 | in the GUD interaction buffer and also in source files. Some of these | |
639 | commands are not available to all the supported debuggers. | |
640 | ||
641 | @table @kbd | |
642 | @item C-c C-l | |
643 | @kindex C-c C-l @r{(GUD)} | |
644 | @itemx C-x C-a C-l | |
645 | @findex gud-refresh | |
646 | Display in another window the last line referred to in the GUD | |
647 | buffer (that is, the line indicated in the last location message). | |
648 | This runs the command @code{gud-refresh}. | |
649 | ||
650 | @item C-c C-s | |
651 | @kindex C-c C-s @r{(GUD)} | |
652 | @itemx C-x C-a C-s | |
653 | @findex gud-step | |
654 | Execute a single line of code (@code{gud-step}). If the line contains | |
655 | a function call, execution stops after entering the called function. | |
656 | ||
657 | @item C-c C-n | |
658 | @kindex C-c C-n @r{(GUD)} | |
659 | @itemx C-x C-a C-n | |
660 | @findex gud-next | |
661 | Execute a single line of code, stepping across entire function calls | |
662 | at full speed (@code{gud-next}). | |
663 | ||
664 | @item C-c C-i | |
665 | @kindex C-c C-i @r{(GUD)} | |
666 | @itemx C-x C-a C-i | |
667 | @findex gud-stepi | |
668 | Execute a single machine instruction (@code{gud-stepi}). | |
669 | ||
670 | @item C-c C-p | |
671 | @kindex C-c C-p @r{(GUD)} | |
672 | @itemx C-x C-a C-p | |
673 | @findex gud-print | |
674 | Evaluate the expression at point (@code{gud-print}). If Emacs | |
675 | does not print the exact expression that you want, mark it as a region | |
676 | first. | |
677 | ||
678 | @need 3000 | |
679 | @item C-c C-r | |
680 | @kindex C-c C-r @r{(GUD)} | |
681 | @itemx C-x C-a C-r | |
682 | @findex gud-cont | |
683 | Continue execution without specifying any stopping point. The program | |
684 | will run until it hits a breakpoint, terminates, or gets a signal that | |
685 | the debugger is checking for (@code{gud-cont}). | |
686 | ||
687 | @need 1000 | |
688 | @item C-c C-d | |
689 | @kindex C-c C-d @r{(GUD)} | |
690 | @itemx C-x C-a C-d | |
691 | @findex gud-remove | |
692 | Delete the breakpoint(s) on the current source line, if any | |
693 | (@code{gud-remove}). If you use this command in the GUD interaction | |
694 | buffer, it applies to the line where the program last stopped. | |
695 | ||
696 | @item C-c C-t | |
697 | @kindex C-c C-t @r{(GUD)} | |
698 | @itemx C-x C-a C-t | |
699 | @findex gud-tbreak | |
700 | Set a temporary breakpoint on the current source line, if any | |
701 | (@code{gud-tbreak}). If you use this command in the GUD interaction | |
702 | buffer, it applies to the line where the program last stopped. | |
703 | ||
704 | @item C-c < | |
705 | @kindex C-c < @r{(GUD)} | |
706 | @itemx C-x C-a < | |
707 | @findex gud-up | |
708 | Select the next enclosing stack frame (@code{gud-up}). This is | |
709 | equivalent to the GDB command @samp{up}. | |
710 | ||
711 | @item C-c > | |
712 | @kindex C-c > @r{(GUD)} | |
713 | @itemx C-x C-a > | |
714 | @findex gud-down | |
715 | Select the next inner stack frame (@code{gud-down}). This is | |
716 | equivalent to the GDB command @samp{down}. | |
717 | ||
718 | @item C-c C-u | |
719 | @kindex C-c C-u @r{(GUD)} | |
720 | @itemx C-x C-a C-u | |
721 | @findex gud-until | |
722 | Continue execution to the current line (@code{gud-until}). The | |
723 | program will run until it hits a breakpoint, terminates, gets a signal | |
724 | that the debugger is checking for, or reaches the line on which the | |
725 | cursor currently sits. | |
726 | ||
727 | @item C-c C-f | |
728 | @kindex C-c C-f @r{(GUD)} | |
729 | @itemx C-x C-a C-f | |
730 | @findex gud-finish | |
731 | Run the program until the selected stack frame returns or | |
732 | stops for some other reason (@code{gud-finish}). | |
733 | @end table | |
734 | ||
735 | If you are using GDB, these additional key bindings are available: | |
736 | ||
737 | @table @kbd | |
738 | @item C-x C-a C-j | |
739 | @kindex C-x C-a C-j @r{(GUD)} | |
740 | @findex gud-jump | |
741 | Only useful in a source buffer, @code{gud-jump} transfers the | |
742 | program's execution point to the current line. In other words, the | |
743 | next line that the program executes will be the one where you gave the | |
744 | command. If the new execution line is in a different function from | |
745 | the previously one, GDB prompts for confirmation since the results may | |
746 | be bizarre. See the GDB manual entry regarding @code{jump} for | |
747 | details. | |
748 | ||
749 | @item @key{TAB} | |
750 | @kindex TAB @r{(GUD)} | |
751 | @findex gud-gdb-complete-command | |
752 | With GDB, complete a symbol name (@code{gud-gdb-complete-command}). | |
753 | This key is available only in the GUD interaction buffer. | |
754 | @end table | |
755 | ||
756 | These commands interpret a numeric argument as a repeat count, when | |
757 | that makes sense. | |
758 | ||
759 | Because @key{TAB} serves as a completion command, you can't use it to | |
760 | enter a tab as input to the program you are debugging with GDB. | |
761 | Instead, type @kbd{C-q @key{TAB}} to enter a tab. | |
762 | ||
763 | @node GUD Customization | |
b424697f | 764 | @subsection GUD Customization |
8cf51b2c GM |
765 | |
766 | @vindex gdb-mode-hook | |
767 | @vindex dbx-mode-hook | |
768 | @vindex sdb-mode-hook | |
769 | @vindex xdb-mode-hook | |
770 | @vindex perldb-mode-hook | |
771 | @vindex pdb-mode-hook | |
772 | @vindex jdb-mode-hook | |
773 | On startup, GUD runs one of the following hooks: @code{gdb-mode-hook}, | |
774 | if you are using GDB; @code{dbx-mode-hook}, if you are using DBX; | |
775 | @code{sdb-mode-hook}, if you are using SDB; @code{xdb-mode-hook}, if you | |
776 | are using XDB; @code{perldb-mode-hook}, for Perl debugging mode; | |
777 | @code{pdb-mode-hook}, for PDB; @code{jdb-mode-hook}, for JDB. You can | |
778 | use these hooks to define custom key bindings for the debugger | |
779 | interaction buffer. @xref{Hooks}. | |
780 | ||
781 | Here is a convenient way to define a command that sends a particular | |
782 | command string to the debugger, and set up a key binding for it in the | |
783 | debugger interaction buffer: | |
784 | ||
785 | @findex gud-def | |
786 | @example | |
787 | (gud-def @var{function} @var{cmdstring} @var{binding} @var{docstring}) | |
788 | @end example | |
789 | ||
790 | This defines a command named @var{function} which sends | |
791 | @var{cmdstring} to the debugger process, and gives it the documentation | |
792 | string @var{docstring}. You can then use the command @var{function} in any | |
793 | buffer. If @var{binding} is non-@code{nil}, @code{gud-def} also binds | |
794 | the command to @kbd{C-c @var{binding}} in the GUD buffer's mode and to | |
795 | @kbd{C-x C-a @var{binding}} generally. | |
796 | ||
797 | The command string @var{cmdstring} may contain certain | |
798 | @samp{%}-sequences that stand for data to be filled in at the time | |
799 | @var{function} is called: | |
800 | ||
801 | @table @samp | |
802 | @item %f | |
803 | The name of the current source file. If the current buffer is the GUD | |
804 | buffer, then the ``current source file'' is the file that the program | |
805 | stopped in. | |
806 | ||
807 | @item %l | |
808 | The number of the current source line. If the current buffer is the GUD | |
809 | buffer, then the ``current source line'' is the line that the program | |
810 | stopped in. | |
811 | ||
812 | @item %e | |
813 | In transient-mark-mode the text in the region, if it is active. | |
814 | Otherwise the text of the C lvalue or function-call expression at or | |
815 | adjacent to point. | |
816 | ||
817 | @item %a | |
818 | The text of the hexadecimal address at or adjacent to point. | |
819 | ||
820 | @item %p | |
821 | The numeric argument of the called function, as a decimal number. If | |
822 | the command is used without a numeric argument, @samp{%p} stands for the | |
823 | empty string. | |
824 | ||
825 | If you don't use @samp{%p} in the command string, the command you define | |
826 | ignores any numeric argument. | |
827 | ||
828 | @item %d | |
829 | The name of the directory of the current source file. | |
830 | ||
831 | @item %c | |
832 | Fully qualified class name derived from the expression surrounding point | |
833 | (jdb only). | |
834 | @end table | |
835 | ||
836 | @node GDB Graphical Interface | |
837 | @subsection GDB Graphical Interface | |
838 | ||
a03334ca | 839 | The command @code{gdb} starts GDB in a graphical interface, using |
abb777ac CY |
840 | Emacs windows for display program state information. With it, you do |
841 | not need to use textual GDB commands; you can control the debugging | |
842 | session with the mouse. For example, you can click in the fringe of a | |
843 | source buffer to set a breakpoint there, or on a stack frame in the | |
844 | stack buffer to select that frame. | |
8cf51b2c GM |
845 | |
846 | This mode requires telling GDB that its ``screen size'' is | |
847 | unlimited, so it sets the height and width accordingly. For correct | |
848 | operation you must not change these values during the GDB session. | |
849 | ||
850 | @vindex gud-gdb-command-name | |
4f45c619 NR |
851 | To run GDB in text command mode, like the other debuggers in Emacs, |
852 | use @kbd{M-x gud-gdb}. You need to use text command mode to debug | |
853 | multiple programs within one Emacs session. | |
8cf51b2c GM |
854 | |
855 | @menu | |
856 | * GDB-UI Layout:: Control the number of displayed buffers. | |
857 | * Source Buffers:: Use the mouse in the fringe/margin to | |
858 | control your program. | |
859 | * Breakpoints Buffer:: A breakpoint control panel. | |
860 | * Stack Buffer:: Select a frame from the call stack. | |
861 | * Other GDB-UI Buffers:: Input/output, locals, registers, | |
862 | assembler, threads and memory buffers. | |
863 | * Watch Expressions:: Monitor variable values in the speedbar. | |
0df6175c | 864 | * Reverse Debugging:: Execute and reverse debug your program. |
8cf51b2c GM |
865 | @end menu |
866 | ||
867 | @node GDB-UI Layout | |
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 | |
995 | Enable/disable the current breakpoint (@code{gdb-toggle-breakpoint}). | |
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 | ||
95dbaaea NR |
1017 | When @code{gdb-many-windows} is non-@code{nil}, the breakpoints buffer |
1018 | shares its window with the threads buffer. To switch from one to the | |
8d6bb99e | 1019 | other click with @kbd{Mouse-1} on the relevant button in the header |
0df6175c | 1020 | line. |
95dbaaea | 1021 | |
8cf51b2c GM |
1022 | @node Stack Buffer |
1023 | @subsubsection Stack Buffer | |
1024 | ||
1025 | The stack buffer displays a @dfn{call stack}, with one line for each | |
1026 | of the nested subroutine calls (@dfn{stack frames}) now active in the | |
1027 | program. @xref{Backtrace,, Backtraces, gdb, The GNU debugger}. | |
1028 | ||
1029 | @findex gdb-frames-select | |
1030 | An arrow in the fringe points to the selected frame or, if the fringe is | |
1031 | not present, the number of the selected frame is displayed in reverse | |
1032 | contrast. To select a frame in GDB, move point in the stack buffer to | |
1033 | that stack frame and type @key{RET} (@code{gdb-frames-select}), or click | |
1034 | @kbd{Mouse-2} on a stack frame. If the locals buffer is visible, | |
1035 | selecting a stack frame updates it to display the local variables of the | |
1036 | new frame. | |
1037 | ||
1038 | @node Other GDB-UI Buffers | |
1039 | @subsubsection Other Buffers | |
1040 | ||
1041 | @table @asis | |
1042 | @item Input/Output Buffer | |
1043 | @vindex gdb-use-separate-io-buffer | |
1044 | If the variable @code{gdb-use-separate-io-buffer} is non-@code{nil}, | |
1045 | the program being debugged takes its input and displays its output | |
1046 | here. Otherwise it uses the GUD buffer for that. To toggle whether | |
1047 | GUD mode uses this buffer, do @kbd{M-x gdb-use-separate-io-buffer}. | |
1048 | This takes effect when you next restart the program you are debugging. | |
1049 | ||
1050 | The history and replay commands from Shell mode are available here, | |
1051 | as are the commands to send signals to the debugged program. | |
1052 | @xref{Shell Mode}. | |
1053 | ||
1054 | @item Locals Buffer | |
1055 | The locals buffer displays the values of local variables of the | |
1056 | current frame for simple data types (@pxref{Frame Info, Frame Info, | |
0df6175c | 1057 | Information on a frame, gdb, The GNU debugger}). Press @key{RET} or |
8cf51b2c GM |
1058 | click @kbd{Mouse-2} on the value if you want to edit it. |
1059 | ||
1060 | Arrays and structures display their type only. With GDB 6.4 or later, | |
1061 | move point to their name and press @key{RET}, or alternatively click | |
1062 | @kbd{Mouse-2} there, to examine their values. With earlier versions | |
1063 | of GDB, use @kbd{Mouse-2} or @key{RET} on the type description | |
1064 | (@samp{[struct/union]} or @samp{[array]}). @xref{Watch Expressions}. | |
1065 | ||
1066 | @item Registers Buffer | |
1067 | @findex toggle-gdb-all-registers | |
1068 | The registers buffer displays the values held by the registers | |
1069 | (@pxref{Registers,,, gdb, The GNU debugger}). Press @key{RET} or | |
1070 | click @kbd{Mouse-2} on a register if you want to edit its value. | |
1071 | With GDB 6.4 or later, recently changed register values display with | |
1072 | @code{font-lock-warning-face}. With earlier versions of GDB, you can | |
1073 | press @key{SPC} to toggle the display of floating point registers | |
1074 | (@code{toggle-gdb-all-registers}). | |
1075 | ||
0df6175c CY |
1076 | @item Assembler Buffer |
1077 | The assembler buffer displays the current frame as machine code. An | |
8cf51b2c GM |
1078 | arrow points to the current instruction, and you can set and remove |
1079 | breakpoints as in a source buffer. Breakpoint icons also appear in | |
1080 | the fringe or margin. | |
1081 | ||
0df6175c CY |
1082 | @item Threads Buffer |
1083 | @findex gdb-threads-select | |
1084 | The threads buffer displays a summary of all threads currently in your | |
1085 | program (@pxref{Threads, Threads, Debugging programs with multiple | |
1086 | threads, gdb, The GNU debugger}). Move point to any thread in the | |
1087 | list and press @key{RET} to select it (@code{gdb-threads-select}) and | |
1088 | display the associated source in the primary source buffer. | |
1089 | Alternatively, click @kbd{Mouse-2} on a thread to select it. If the | |
1090 | locals buffer is visible, its contents update to display the variables | |
1091 | that are local in the new thread. | |
1092 | ||
1093 | When there is more than one main thread and the threads buffer is | |
1094 | present, Emacs displays the selected thread number in the mode line of | |
1095 | many of the GDB-UI Buffers. | |
1096 | ||
8cf51b2c GM |
1097 | @item Memory Buffer |
1098 | The memory buffer lets you examine sections of program memory | |
1099 | (@pxref{Memory, Memory, Examining memory, gdb, The GNU debugger}). | |
1100 | Click @kbd{Mouse-1} on the appropriate part of the header line to | |
1101 | change the starting address or number of data items that the buffer | |
4a3a621f NR |
1102 | displays. Alternatively, use @kbd{S} or @kbd{N} respectively. Click |
1103 | @kbd{Mouse-3} on the header line to select the display format or unit | |
1104 | size for these data items. | |
8cf51b2c GM |
1105 | @end table |
1106 | ||
1a19cb6a NR |
1107 | When @code{gdb-many-windows} is non-@code{nil}, the threads buffer |
1108 | shares its window with the breakpoints buffer, and the locals buffer | |
0df6175c CY |
1109 | with the registers buffer. To switch from one to the other click with |
1110 | @kbd{Mouse-1} on the relevant button in the header line. | |
1a19cb6a | 1111 | |
8cf51b2c GM |
1112 | @node Watch Expressions |
1113 | @subsubsection Watch Expressions | |
1114 | @cindex Watching expressions in GDB | |
1115 | ||
1116 | @findex gud-watch | |
1117 | @kindex C-x C-a C-w @r{(GUD)} | |
1118 | If you want to see how a variable changes each time your program | |
1119 | stops, move point into the variable name and click on the watch icon | |
1120 | in the tool bar (@code{gud-watch}) or type @kbd{C-x C-a C-w}. If you | |
1121 | specify a prefix argument, you can enter the variable name in the | |
1122 | minibuffer. | |
1123 | ||
1124 | Each watch expression is displayed in the speedbar. Complex data | |
1125 | types, such as arrays, structures and unions are represented in a tree | |
1126 | format. Leaves and simple data types show the name of the expression | |
1127 | and its value and, when the speedbar frame is selected, display the | |
1128 | type as a tooltip. Higher levels show the name, type and address | |
1129 | value for pointers and just the name and type otherwise. Root expressions | |
1130 | also display the frame address as a tooltip to help identify the frame | |
1131 | in which they were defined. | |
1132 | ||
1133 | To expand or contract a complex data type, click @kbd{Mouse-2} or | |
1134 | press @key{SPC} on the tag to the left of the expression. Emacs asks | |
1135 | for confirmation before expanding the expression if its number of | |
1136 | immediate children exceeds the value of the variable | |
1137 | @code{gdb-max-children}. | |
1138 | ||
1139 | @kindex D @r{(GDB speedbar)} | |
1140 | @findex gdb-var-delete | |
1141 | To delete a complex watch expression, move point to the root | |
1142 | expression in the speedbar and type @kbd{D} (@code{gdb-var-delete}). | |
1143 | ||
1144 | @kindex RET @r{(GDB speedbar)} | |
1145 | @findex gdb-edit-value | |
1146 | To edit a variable with a simple data type, or a simple element of a | |
1147 | complex data type, move point there in the speedbar and type @key{RET} | |
1148 | (@code{gdb-edit-value}). Or you can click @kbd{Mouse-2} on a value to | |
1149 | edit it. Either way, this reads the new value using the minibuffer. | |
1150 | ||
1151 | @vindex gdb-show-changed-values | |
1152 | If you set the variable @code{gdb-show-changed-values} to | |
1153 | non-@code{nil} (the default value), Emacs uses | |
1154 | @code{font-lock-warning-face} to highlight values that have recently | |
1155 | changed and @code{shadow} face to make variables which have gone out of | |
1156 | scope less noticeable. When a variable goes out of scope you can't | |
1157 | edit its value. | |
1158 | ||
975900f9 | 1159 | @vindex gdb-delete-out-of-scope |
32ef39ff NR |
1160 | If the variable @code{gdb-delete-out-of-scope} is non-@code{nil} |
1161 | (the default value), Emacs automatically deletes watch expressions | |
1162 | which go out of scope. Sometimes, when re-entering the same function, | |
de933755 CY |
1163 | it may be useful to set this value to @code{nil} so that you don't |
1164 | need to recreate the watch expression. | |
975900f9 | 1165 | |
8cf51b2c GM |
1166 | @vindex gdb-use-colon-colon-notation |
1167 | If the variable @code{gdb-use-colon-colon-notation} is | |
1168 | non-@code{nil}, Emacs uses the @samp{@var{function}::@var{variable}} | |
1169 | format. This allows the user to display watch expressions which share | |
1170 | the same variable name. The default value is @code{nil}. | |
1171 | ||
1172 | @vindex gdb-speedbar-auto-raise | |
1173 | To automatically raise the speedbar every time the display of watch | |
1174 | expressions updates, set @code{gdb-speedbar-auto-raise} to | |
1175 | non-@code{nil}. This can be useful if you are debugging with a full | |
1176 | screen Emacs frame. | |
1177 | ||
0df6175c CY |
1178 | @node Reverse Debugging |
1179 | @subsubsection Reverse Debugging | |
1180 | ||
1181 | The GDB tool bar shares many buttons with the other GUD debuggers | |
1182 | for tasks like stepping and printing expressions. It also has a | |
1183 | further set of buttons that allow reverse debugging (@pxref{Process | |
1184 | Record and Replay, , ,gdb, The GNU debugger}). This is useful when it | |
1185 | takes a long time to reproduce the conditions where your program fails | |
1186 | or for transient problems, like race conditions in multi-threaded | |
1187 | programs, where a failure might otherwise be hard to reproduce. | |
1188 | ||
1189 | To use reverse debugging, set a breakpoint slightly before the | |
1190 | location of interest and run your program to that point. Enable | |
1191 | process recording by clicking on the record button. At this point, a | |
1192 | new set of buttons appear. These buttons allow program execution in | |
1193 | the reverse direction. Run your program over the code where the | |
1194 | problem occurs, and then use the new set of buttons to retrace your | |
1195 | steps, examine values, and analyze the problem. When analysis is | |
1196 | complete, turn off process recording by clicking on the record button | |
1197 | again. | |
8d6bb99e | 1198 | |
8cf51b2c GM |
1199 | @node Executing Lisp |
1200 | @section Executing Lisp Expressions | |
1201 | ||
1202 | Emacs has several different major modes for Lisp and Scheme. They are | |
1203 | the same in terms of editing commands, but differ in the commands for | |
1204 | executing Lisp expressions. Each mode has its own purpose. | |
1205 | ||
1206 | @table @asis | |
1207 | @item Emacs-Lisp mode | |
1208 | The mode for editing source files of programs to run in Emacs Lisp. | |
1209 | This mode defines @kbd{C-M-x} to evaluate the current defun. | |
1210 | @xref{Lisp Libraries}. | |
1211 | @item Lisp Interaction mode | |
1212 | The mode for an interactive session with Emacs Lisp. It defines | |
1213 | @kbd{C-j} to evaluate the sexp before point and insert its value in the | |
1214 | buffer. @xref{Lisp Interaction}. | |
1215 | @item Lisp mode | |
1216 | The mode for editing source files of programs that run in Lisps other | |
1217 | than Emacs Lisp. This mode defines @kbd{C-M-x} to send the current defun | |
1218 | to an inferior Lisp process. @xref{External Lisp}. | |
1219 | @item Inferior Lisp mode | |
1220 | The mode for an interactive session with an inferior Lisp process. | |
1221 | This mode combines the special features of Lisp mode and Shell mode | |
1222 | (@pxref{Shell Mode}). | |
1223 | @item Scheme mode | |
1224 | Like Lisp mode but for Scheme programs. | |
1225 | @item Inferior Scheme mode | |
1226 | The mode for an interactive session with an inferior Scheme process. | |
1227 | @end table | |
1228 | ||
1229 | Most editing commands for working with Lisp programs are in fact | |
1230 | available globally. @xref{Programs}. | |
1231 | ||
1232 | @node Lisp Libraries | |
1233 | @section Libraries of Lisp Code for Emacs | |
1234 | @cindex libraries | |
1235 | @cindex loading Lisp code | |
1236 | ||
1237 | Lisp code for Emacs editing commands is stored in files whose names | |
1238 | conventionally end in @file{.el}. This ending tells Emacs to edit them in | |
1239 | Emacs-Lisp mode (@pxref{Executing Lisp}). | |
1240 | ||
1241 | @cindex byte code | |
1242 | Emacs Lisp code can be compiled into byte-code, which loads faster, | |
1243 | takes up less space, and executes faster. @xref{Byte Compilation,, | |
1244 | Byte Compilation, elisp, the Emacs Lisp Reference Manual}. By | |
1245 | convention, the compiled code for a library goes in a separate file | |
1246 | whose name ends in @samp{.elc}. Thus, the compiled code for | |
1247 | @file{foo.el} goes in @file{foo.elc}. | |
1248 | ||
1249 | @findex load-file | |
1250 | To execute a file of Emacs Lisp code, use @kbd{M-x load-file}. This | |
1251 | command reads a file name using the minibuffer and then executes the | |
1252 | contents of that file as Lisp code. It is not necessary to visit the | |
1253 | file first; in any case, this command reads the file as found on disk, | |
1254 | not text in an Emacs buffer. | |
1255 | ||
1256 | @findex load | |
1257 | @findex load-library | |
1258 | Once a file of Lisp code is installed in the Emacs Lisp library | |
1259 | directories, users can load it using @kbd{M-x load-library}. Programs | |
1260 | can load it by calling @code{load}, a more primitive function that is | |
1261 | similar but accepts some additional arguments. | |
1262 | ||
1263 | @kbd{M-x load-library} differs from @kbd{M-x load-file} in that it | |
1264 | searches a sequence of directories and tries three file names in each | |
1265 | directory. Suppose your argument is @var{lib}; the three names are | |
1266 | @file{@var{lib}.elc}, @file{@var{lib}.el}, and lastly just | |
1267 | @file{@var{lib}}. If @file{@var{lib}.elc} exists, it is by convention | |
1268 | the result of compiling @file{@var{lib}.el}; it is better to load the | |
1269 | compiled file, since it will load and run faster. | |
1270 | ||
1271 | If @code{load-library} finds that @file{@var{lib}.el} is newer than | |
1272 | @file{@var{lib}.elc} file, it issues a warning, because it's likely | |
1273 | that somebody made changes to the @file{.el} file and forgot to | |
1274 | recompile it. Nonetheless, it loads @file{@var{lib}.elc}. This is | |
1275 | because people often leave unfinished edits the source file, and don't | |
1276 | recompile it until they think it is ready to use. | |
1277 | ||
8cf51b2c | 1278 | @vindex load-path |
1557ef4f CY |
1279 | The variable @code{load-path} specifies the sequence of directories |
1280 | searched by @kbd{M-x load-library}. Its value should be a list of | |
f3ed4f26 CY |
1281 | strings that are directory names; in addition, @code{nil} in this list |
1282 | stands for the current default directory. (Generally, it is not a | |
1283 | good idea to put @code{nil} in the list; if you find yourself wishing | |
1284 | that @code{nil} were in the list, most likely what you really want is | |
1285 | to do @kbd{M-x load-file} this once.) | |
1557ef4f CY |
1286 | |
1287 | The default value of @code{load-path} is a list of directories where | |
8cf51b2c | 1288 | the Lisp code for Emacs itself is stored. If you have libraries of |
1557ef4f CY |
1289 | your own, put them in a single directory and add that directory to |
1290 | @code{load-path}, by adding a line like this to your init file | |
1291 | (@pxref{Init File}): | |
1292 | ||
1293 | @example | |
1294 | (add-to-list 'load-path "/path/to/lisp/libraries") | |
1295 | @end example | |
8cf51b2c GM |
1296 | |
1297 | @cindex autoload | |
e8d2d3fb CY |
1298 | Some commands are @dfn{autoloaded}: when you run them, Emacs will |
1299 | automatically load the associated library first. For instance, the | |
1300 | @code{compile} and @code{compilation-mode} commands | |
1301 | (@pxref{Compilation}) are autoloaded; if you call either command, | |
1302 | Emacs automatically loads the @code{compile} library. In contrast, | |
1303 | the command @code{recompile} is not autoloaded, so it is unavailable | |
1304 | until you load the @code{compile} library. | |
8cf51b2c GM |
1305 | |
1306 | @vindex load-dangerous-libraries | |
1307 | @cindex Lisp files byte-compiled by XEmacs | |
1308 | By default, Emacs refuses to load compiled Lisp files which were | |
1309 | compiled with XEmacs, a modified versions of Emacs---they can cause | |
1310 | Emacs to crash. Set the variable @code{load-dangerous-libraries} to | |
1311 | @code{t} if you want to try loading them. | |
1312 | ||
1313 | @node Lisp Eval | |
1314 | @section Evaluating Emacs Lisp Expressions | |
1315 | @cindex Emacs-Lisp mode | |
1316 | @cindex mode, Emacs-Lisp | |
1317 | ||
1318 | @findex emacs-lisp-mode | |
1319 | Lisp programs intended to be run in Emacs should be edited in | |
1320 | Emacs-Lisp mode; this happens automatically for file names ending in | |
1321 | @file{.el}. By contrast, Lisp mode itself is used for editing Lisp | |
1322 | programs intended for other Lisp systems. To switch to Emacs-Lisp mode | |
1323 | explicitly, use the command @kbd{M-x emacs-lisp-mode}. | |
1324 | ||
1325 | For testing of Lisp programs to run in Emacs, it is often useful to | |
1326 | evaluate part of the program as it is found in the Emacs buffer. For | |
1327 | example, after changing the text of a Lisp function definition, | |
1328 | evaluating the definition installs the change for future calls to the | |
1329 | function. Evaluation of Lisp expressions is also useful in any kind of | |
1330 | editing, for invoking noninteractive functions (functions that are | |
1331 | not commands). | |
1332 | ||
1333 | @table @kbd | |
1334 | @item M-: | |
1335 | Read a single Lisp expression in the minibuffer, evaluate it, and print | |
1336 | the value in the echo area (@code{eval-expression}). | |
1337 | @item C-x C-e | |
1338 | Evaluate the Lisp expression before point, and print the value in the | |
1339 | echo area (@code{eval-last-sexp}). | |
1340 | @item C-M-x | |
1341 | Evaluate the defun containing or after point, and print the value in | |
1342 | the echo area (@code{eval-defun}). | |
1343 | @item M-x eval-region | |
1344 | Evaluate all the Lisp expressions in the region. | |
1345 | @item M-x eval-buffer | |
1346 | Evaluate all the Lisp expressions in the buffer. | |
1347 | @end table | |
1348 | ||
1349 | @ifinfo | |
1350 | @c This uses ``colon'' instead of a literal `:' because Info cannot | |
1351 | @c cope with a `:' in a menu | |
1352 | @kindex M-@key{colon} | |
1353 | @end ifinfo | |
1354 | @ifnotinfo | |
1355 | @kindex M-: | |
1356 | @end ifnotinfo | |
1357 | @findex eval-expression | |
1358 | @kbd{M-:} (@code{eval-expression}) is the most basic command for evaluating | |
1359 | a Lisp expression interactively. It reads the expression using the | |
1360 | minibuffer, so you can execute any expression on a buffer regardless of | |
1361 | what the buffer contains. When the expression is evaluated, the current | |
1362 | buffer is once again the buffer that was current when @kbd{M-:} was | |
1363 | typed. | |
1364 | ||
1365 | @kindex C-M-x @r{(Emacs-Lisp mode)} | |
1366 | @findex eval-defun | |
1367 | In Emacs-Lisp mode, the key @kbd{C-M-x} is bound to the command | |
1368 | @code{eval-defun}, which parses the defun containing or following point | |
1369 | as a Lisp expression and evaluates it. The value is printed in the echo | |
1370 | area. This command is convenient for installing in the Lisp environment | |
1371 | changes that you have just made in the text of a function definition. | |
1372 | ||
1373 | @kbd{C-M-x} treats @code{defvar} expressions specially. Normally, | |
1374 | evaluating a @code{defvar} expression does nothing if the variable it | |
1375 | defines already has a value. But @kbd{C-M-x} unconditionally resets the | |
1376 | variable to the initial value specified in the @code{defvar} expression. | |
1377 | @code{defcustom} expressions are treated similarly. | |
1378 | This special feature is convenient for debugging Lisp programs. | |
1379 | Typing @kbd{C-M-x} on a @code{defface} expression reinitializes | |
1380 | the face according to the @code{defface} specification. | |
1381 | ||
1382 | @kindex C-x C-e | |
1383 | @findex eval-last-sexp | |
1384 | The command @kbd{C-x C-e} (@code{eval-last-sexp}) evaluates the Lisp | |
1385 | expression preceding point in the buffer, and displays the value in the | |
1386 | echo area. It is available in all major modes, not just Emacs-Lisp | |
1387 | mode. It does not treat @code{defvar} specially. | |
1388 | ||
1389 | When the result of an evaluation is an integer, you can type | |
1390 | @kbd{C-x C-e} a second time to display the value of the integer result | |
1391 | in additional formats (octal, hexadecimal, and character). | |
1392 | ||
1393 | If @kbd{C-x C-e}, or @kbd{M-:} is given a numeric argument, it | |
1394 | inserts the value into the current buffer at point, rather than | |
1395 | displaying it in the echo area. The argument's value does not matter. | |
1396 | @kbd{C-M-x} with a numeric argument instruments the function | |
1397 | definition for Edebug (@pxref{Instrumenting, Instrumenting for Edebug,, elisp, the Emacs Lisp Reference Manual}). | |
1398 | ||
1399 | @findex eval-region | |
1400 | @findex eval-buffer | |
1401 | The most general command for evaluating Lisp expressions from a buffer | |
1402 | is @code{eval-region}. @kbd{M-x eval-region} parses the text of the | |
1403 | region as one or more Lisp expressions, evaluating them one by one. | |
1404 | @kbd{M-x eval-buffer} is similar but evaluates the entire | |
1405 | buffer. This is a reasonable way to install the contents of a file of | |
1406 | Lisp code that you are ready to test. Later, as you find bugs and | |
1407 | change individual functions, use @kbd{C-M-x} on each function that you | |
1408 | change. This keeps the Lisp world in step with the source file. | |
1409 | ||
1410 | @vindex eval-expression-print-level | |
1411 | @vindex eval-expression-print-length | |
1412 | @vindex eval-expression-debug-on-error | |
1413 | The two customizable variables @code{eval-expression-print-level} and | |
1414 | @code{eval-expression-print-length} control the maximum depth and length | |
1415 | of lists to print in the result of the evaluation commands before | |
1416 | abbreviating them. @code{eval-expression-debug-on-error} controls | |
1417 | whether evaluation errors invoke the debugger when these commands are | |
1418 | used; its default is @code{t}. | |
1419 | ||
1420 | @node Lisp Interaction | |
1421 | @section Lisp Interaction Buffers | |
1422 | ||
a03334ca CY |
1423 | When Emacs starts up, it contains a buffer named @samp{*scratch*}, |
1424 | which is provided for evaluating Lisp expressions interactively inside | |
1425 | Emacs. Its major mode is Lisp Interaction mode. | |
8cf51b2c | 1426 | |
a03334ca CY |
1427 | @findex eval-print-last-sexp |
1428 | @kindex C-j @r{(Lisp Interaction mode)} | |
1429 | The simplest way to use the @samp{*scratch*} buffer is to insert | |
1430 | Lisp expressions and type @kbd{C-j} (@code{eval-print-last-sexp}) | |
1431 | after each expression. This command reads the Lisp expression before | |
1432 | point, evaluates it, and inserts the value in printed representation | |
1433 | before point. The result is a complete typescript of the expressions | |
1434 | you have evaluated and their values. | |
8cf51b2c | 1435 | |
be77bd45 CY |
1436 | @vindex initial-scratch-message |
1437 | At startup, the @samp{*scratch*} buffer contains a short message, in | |
1438 | the form of a Lisp comment, that explains what it is for. This | |
1439 | message is controlled by the variable @code{initial-scratch-message}, | |
1440 | which should be either a string or @code{nil}. If you set it to the | |
1441 | empty string, or @code{nil}, the initial message is suppressed. | |
1442 | ||
8cf51b2c | 1443 | @findex lisp-interaction-mode |
a03334ca CY |
1444 | All other commands in Lisp Interaction mode are the same as in Emacs |
1445 | Lisp mode. You can enable Lisp Interaction mode by typing @kbd{M-x | |
1446 | lisp-interaction-mode}. | |
8cf51b2c GM |
1447 | |
1448 | @findex ielm | |
1449 | An alternative way of evaluating Emacs Lisp expressions interactively | |
1450 | is to use Inferior Emacs-Lisp mode, which provides an interface rather | |
1451 | like Shell mode (@pxref{Shell Mode}) for evaluating Emacs Lisp | |
1452 | expressions. Type @kbd{M-x ielm} to create an @samp{*ielm*} buffer | |
1453 | which uses this mode. For more information see that command's | |
1454 | documentation. | |
1455 | ||
1456 | @node External Lisp | |
1457 | @section Running an External Lisp | |
1458 | ||
1459 | Emacs has facilities for running programs in other Lisp systems. You can | |
1460 | run a Lisp process as an inferior of Emacs, and pass expressions to it to | |
1461 | be evaluated. You can also pass changed function definitions directly from | |
1462 | the Emacs buffers in which you edit the Lisp programs to the inferior Lisp | |
1463 | process. | |
1464 | ||
1465 | @findex run-lisp | |
1466 | @vindex inferior-lisp-program | |
1467 | @kindex C-x C-z | |
1468 | To run an inferior Lisp process, type @kbd{M-x run-lisp}. This runs | |
1469 | the program named @code{lisp}, the same program you would run by typing | |
1470 | @code{lisp} as a shell command, with both input and output going through | |
1471 | an Emacs buffer named @samp{*lisp*}. That is to say, any ``terminal | |
1472 | output'' from Lisp will go into the buffer, advancing point, and any | |
1473 | ``terminal input'' for Lisp comes from text in the buffer. (You can | |
1474 | change the name of the Lisp executable file by setting the variable | |
1475 | @code{inferior-lisp-program}.) | |
1476 | ||
1477 | To give input to Lisp, go to the end of the buffer and type the input, | |
1478 | terminated by @key{RET}. The @samp{*lisp*} buffer is in Inferior Lisp | |
1479 | mode, which combines the special characteristics of Lisp mode with most | |
1480 | of the features of Shell mode (@pxref{Shell Mode}). The definition of | |
1481 | @key{RET} to send a line to a subprocess is one of the features of Shell | |
1482 | mode. | |
1483 | ||
1484 | @findex lisp-mode | |
1485 | For the source files of programs to run in external Lisps, use Lisp | |
1486 | mode. You can switch to this mode with @kbd{M-x lisp-mode}, and it is | |
1487 | used automatically for files whose names end in @file{.l}, | |
1488 | @file{.lsp}, or @file{.lisp}. | |
1489 | ||
1490 | @kindex C-M-x @r{(Lisp mode)} | |
1491 | @findex lisp-eval-defun | |
1492 | When you edit a function in a Lisp program you are running, the easiest | |
1493 | way to send the changed definition to the inferior Lisp process is the key | |
1494 | @kbd{C-M-x}. In Lisp mode, this runs the function @code{lisp-eval-defun}, | |
1495 | which finds the defun around or following point and sends it as input to | |
1496 | the Lisp process. (Emacs can send input to any inferior process regardless | |
1497 | of what buffer is current.) | |
1498 | ||
1499 | Contrast the meanings of @kbd{C-M-x} in Lisp mode (for editing | |
1500 | programs to be run in another Lisp system) and Emacs-Lisp mode (for | |
1501 | editing Lisp programs to be run in Emacs; see @pxref{Lisp Eval}): in | |
1502 | both modes it has the effect of installing the function definition | |
1503 | that point is in, but the way of doing so is different according to | |
1504 | where the relevant Lisp environment is found. | |
1505 | ||
1506 | ||
1507 | @ignore | |
1508 | arch-tag: 9c3c2f71-b332-4144-8500-3ff9945a50ed | |
1509 | @end ignore |