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6bf7aab6 | 1 | @c This is part of the Emacs manual. |
739a80b3 | 2 | @c Copyright (C) 1985,86,87,93,94,95,97,2000,2001 Free Software Foundation, Inc. |
6bf7aab6 | 3 | @c See file emacs.texi for copying conditions. |
ffb1af2b | 4 | @node Building, Maintaining, Programs, Top |
6bf7aab6 DL |
5 | @chapter Compiling and Testing Programs |
6 | @cindex building programs | |
7 | @cindex program building | |
8 | @cindex running Lisp functions | |
9 | ||
10 | The previous chapter discusses the Emacs commands that are useful for | |
11 | making changes in programs. This chapter deals with commands that assist | |
12 | in the larger process of developing and maintaining programs. | |
13 | ||
14 | @menu | |
15 | * Compilation:: Compiling programs in languages other | |
16 | than Lisp (C, Pascal, etc.). | |
17 | * Grep Searching:: Running grep as if it were a compiler. | |
18 | * Compilation Mode:: The mode for visiting compiler errors. | |
19 | * Compilation Shell:: Customizing your shell properly | |
20 | for use in the compilation buffer. | |
177c0ea7 JB |
21 | * Debuggers:: Running symbolic debuggers for non-Lisp programs. |
22 | * Executing Lisp:: Various modes for editing Lisp programs, | |
6bf7aab6 | 23 | with different facilities for running |
177c0ea7 | 24 | the Lisp programs. |
6bf7aab6 DL |
25 | * Libraries: Lisp Libraries. Creating Lisp programs to run in Emacs. |
26 | * Interaction: Lisp Interaction. Executing Lisp in an Emacs buffer. | |
27 | * Eval: Lisp Eval. Executing a single Lisp expression in Emacs. | |
177c0ea7 | 28 | * External Lisp:: Communicating through Emacs with a separate Lisp. |
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29 | @end menu |
30 | ||
31 | @node Compilation | |
32 | @section Running Compilations under Emacs | |
33 | @cindex inferior process | |
34 | @cindex make | |
35 | @cindex compilation errors | |
36 | @cindex error log | |
37 | ||
38 | Emacs can run compilers for noninteractive languages such as C and | |
39 | Fortran as inferior processes, feeding the error log into an Emacs buffer. | |
40 | It can also parse the error messages and show you the source lines where | |
41 | compilation errors occurred. | |
42 | ||
43 | @table @kbd | |
44 | @item M-x compile | |
74b1aac1 | 45 | Run a compiler asynchronously under Emacs, with error messages going to |
58fa012d | 46 | the @samp{*compilation*} buffer. |
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47 | @item M-x recompile |
48 | Invoke a compiler with the same command as in the last invocation of | |
49 | @kbd{M-x compile}. | |
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50 | @item M-x grep |
51 | Run @code{grep} asynchronously under Emacs, with matching lines | |
52 | listed in the buffer named @samp{*grep*}. | |
53 | @item M-x grep-find | |
54 | Run @code{grep} via @code{find}, with user-specified arguments, and | |
55 | collect output in the buffer named @samp{*grep*}. | |
56 | @item M-x kill-compilation | |
57 | @itemx M-x kill-grep | |
58 | Kill the running compilation or @code{grep} subprocess. | |
59 | @end table | |
60 | ||
61 | @findex compile | |
62 | To run @code{make} or another compilation command, do @kbd{M-x | |
63 | compile}. This command reads a shell command line using the minibuffer, | |
64 | and then executes the command in an inferior shell, putting output in | |
65 | the buffer named @samp{*compilation*}. The current buffer's default | |
66 | directory is used as the working directory for the execution of the | |
67 | command; normally, therefore, the compilation happens in this | |
68 | directory. | |
69 | ||
70 | @vindex compile-command | |
49ba5d16 RS |
71 | When the shell command line is read, the minibuffer appears |
72 | containing a default command line, which is the command you used the | |
73 | last time you did @kbd{M-x compile}. If you type just @key{RET}, the | |
74 | same command line is used again. For the first @kbd{M-x compile}, the | |
75 | default is @samp{make -k}, which is correct most of the time for | |
333c5fc5 | 76 | nontrivial programs. (@xref{Top,, Make, make, GNU Make Manual}.) |
49ba5d16 | 77 | The default compilation command comes from the variable |
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78 | @code{compile-command}; if the appropriate compilation command for a |
79 | file is something other than @samp{make -k}, it can be useful for the | |
80 | file to specify a local value for @code{compile-command} (@pxref{File | |
81 | Variables}). | |
82 | ||
83 | Starting a compilation displays the buffer @samp{*compilation*} in | |
84 | another window but does not select it. The buffer's mode line tells you | |
85 | whether compilation is finished, with the word @samp{run} or @samp{exit} | |
86 | inside the parentheses. You do not have to keep this buffer visible; | |
87 | compilation continues in any case. While a compilation is going on, the | |
88 | string @samp{Compiling} appears in the mode lines of all windows. When | |
89 | this string disappears, the compilation is finished. | |
90 | ||
91 | If you want to watch the compilation transcript as it appears, switch | |
92 | to the @samp{*compilation*} buffer and move point to the end of the | |
93 | buffer. When point is at the end, new compilation output is inserted | |
94 | above point, which remains at the end. If point is not at the end of | |
95 | the buffer, it remains fixed while more compilation output is added at | |
96 | the end of the buffer. | |
97 | ||
09e58ba6 | 98 | @cindex compilation buffer, keeping current position at the end |
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99 | @vindex compilation-scroll-output |
100 | If you set the variable @code{compilation-scroll-output} to a | |
101 | non-@code{nil} value, then the compilation buffer always scrolls to | |
102 | follow output as it comes in. | |
103 | ||
104 | @findex kill-compilation | |
43b4d3c0 RS |
105 | When the compiler process terminates, for whatever reason, the mode |
106 | line of the @samp{*compilation*} buffer changes to say @samp{signal} | |
107 | instead of @samp{run}. Starting a new compilation also kills any | |
108 | running compilation, as only one can exist at any time. However, | |
109 | @kbd{M-x compile} asks for confirmation before actually killing a | |
110 | compilation that is running. You can also kill the compilation | |
111 | process with @kbd{M-x kill-compilation}. | |
6bf7aab6 | 112 | |
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113 | @findex recompile |
114 | To rerun the last compilation with the same command, type @kbd{M-x | |
115 | recompile}. This automatically reuses the compilation command from the | |
116 | last invocation of @kbd{M-x compile}. | |
117 | ||
43b4d3c0 | 118 | Emacs does not expect a compiler process to launch asynchronous |
266e712e | 119 | subprocesses; if it does, and they keep running after the main |
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120 | compiler process has terminated, Emacs may kill them or their output |
121 | may not arrive in Emacs. To avoid this problem, make the main process | |
122 | wait for its subprocesses to finish. In a shell script, you can do this | |
123 | using @samp{$!} and @samp{wait}, like this: | |
124 | ||
125 | @example | |
126 | (sleep 10; echo 2nd)& pid=$! # @r{Record pid of subprocess} | |
127 | echo first message | |
128 | wait $pid # @r{Wait for subprocess} | |
129 | @end example | |
266e712e | 130 | |
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131 | @node Grep Searching |
132 | @section Searching with Grep under Emacs | |
133 | ||
134 | @findex grep | |
135 | Just as you can run a compiler from Emacs and then visit the lines | |
136 | where there were compilation errors, you can also run @code{grep} and | |
137 | then visit the lines on which matches were found. This works by | |
138 | treating the matches reported by @code{grep} as if they were ``errors.'' | |
139 | ||
140 | To do this, type @kbd{M-x grep}, then enter a command line that | |
141 | specifies how to run @code{grep}. Use the same arguments you would give | |
142 | @code{grep} when running it normally: a @code{grep}-style regexp | |
143 | (usually in single-quotes to quote the shell's special characters) | |
144 | followed by file names, which may use wildcards. The output from | |
145 | @code{grep} goes in the @samp{*grep*} buffer. You can find the | |
146 | corresponding lines in the original files using @kbd{C-x `} and | |
147 | @key{RET}, as with compilation errors. | |
148 | ||
149 | If you specify a prefix argument for @kbd{M-x grep}, it figures out | |
150 | the tag (@pxref{Tags}) around point, and puts that into the default | |
151 | @code{grep} command. | |
152 | ||
153 | @findex grep-find | |
154 | The command @kbd{M-x grep-find} is similar to @kbd{M-x grep}, but it | |
155 | supplies a different initial default for the command---one that runs | |
156 | both @code{find} and @code{grep}, so as to search every file in a | |
157 | directory tree. See also the @code{find-grep-dired} command, | |
158 | in @ref{Dired and Find}. | |
159 | ||
160 | @node Compilation Mode | |
161 | @section Compilation Mode | |
162 | ||
163 | @findex compile-goto-error | |
164 | @cindex Compilation mode | |
165 | @cindex mode, Compilation | |
166 | The @samp{*compilation*} buffer uses a special major mode, Compilation | |
167 | mode, whose main feature is to provide a convenient way to look at the | |
168 | source line where the error happened. | |
169 | ||
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170 | If you set the variable @code{compilation-scroll-output} to a |
171 | non-@code{nil} value, then the compilation buffer always scrolls to | |
172 | follow output as it comes in. | |
173 | ||
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174 | @table @kbd |
175 | @item C-x ` | |
176 | Visit the locus of the next compiler error message or @code{grep} match. | |
177 | @item @key{RET} | |
178 | Visit the locus of the error message that point is on. | |
179 | This command is used in the compilation buffer. | |
180 | @item Mouse-2 | |
181 | Visit the locus of the error message that you click on. | |
182 | @end table | |
183 | ||
184 | @kindex C-x ` | |
185 | @findex next-error | |
186 | You can visit the source for any particular error message by moving | |
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187 | point in the @samp{*compilation*} buffer to that error message and |
188 | typing @key{RET} (@code{compile-goto-error}). Alternatively, you can | |
189 | click @kbd{Mouse-2} on the error message; you need not switch to the | |
190 | @samp{*compilation*} buffer first. | |
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191 | |
192 | To parse the compiler error messages sequentially, type @kbd{C-x `} | |
193 | (@code{next-error}). The character following the @kbd{C-x} is the | |
194 | backquote or ``grave accent,'' not the single-quote. This command is | |
195 | available in all buffers, not just in @samp{*compilation*}; it displays | |
196 | the next error message at the top of one window and source location of | |
197 | the error in another window. | |
198 | ||
199 | The first time @kbd{C-x `} is used after the start of a compilation, | |
200 | it moves to the first error's location. Subsequent uses of @kbd{C-x `} | |
201 | advance down to subsequent errors. If you visit a specific error | |
202 | message with @key{RET} or @kbd{Mouse-2}, subsequent @kbd{C-x `} | |
203 | commands advance from there. When @kbd{C-x `} gets to the end of the | |
204 | buffer and finds no more error messages to visit, it fails and signals | |
205 | an Emacs error. | |
206 | ||
207 | @kbd{C-u C-x `} starts scanning from the beginning of the compilation | |
208 | buffer. This is one way to process the same set of errors again. | |
209 | ||
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210 | @vindex compilation-error-regexp-alist |
211 | @vindex grep-regexp-alist | |
212 | To parse messages from the compiler, Compilation mode uses the | |
213 | variable @code{compilation-error-regexp-alist} which lists various | |
214 | formats of error messages and tells Emacs how to extract the source file | |
215 | and the line number from the text of a message. If your compiler isn't | |
216 | supported, you can tailor Compilation mode to it by adding elements to | |
217 | that list. A similar variable @code{grep-regexp-alist} tells Emacs how | |
218 | to parse output of a @code{grep} command. | |
219 | ||
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220 | Compilation mode also redefines the keys @key{SPC} and @key{DEL} to |
221 | scroll by screenfuls, and @kbd{M-n} and @kbd{M-p} to move to the next or | |
222 | previous error message. You can also use @kbd{M-@{} and @kbd{M-@}} to | |
223 | move up or down to an error message for a different source file. | |
224 | ||
225 | The features of Compilation mode are also available in a minor mode | |
226 | called Compilation Minor mode. This lets you parse error messages in | |
227 | any buffer, not just a normal compilation output buffer. Type @kbd{M-x | |
228 | compilation-minor-mode} to enable the minor mode. This defines the keys | |
229 | @key{RET} and @kbd{Mouse-2}, as in the Compilation major mode. | |
230 | ||
231 | Compilation minor mode works in any buffer, as long as the contents | |
232 | are in a format that it understands. In an Rlogin buffer (@pxref{Remote | |
233 | Host}), Compilation minor mode automatically accesses remote source | |
234 | files by FTP (@pxref{File Names}). | |
235 | ||
236 | @node Compilation Shell | |
237 | @section Subshells for Compilation | |
238 | ||
239 | Emacs uses a shell to run the compilation command, but specifies | |
240 | the option for a noninteractive shell. This means, in particular, that | |
241 | the shell should start with no prompt. If you find your usual shell | |
242 | prompt making an unsightly appearance in the @samp{*compilation*} | |
243 | buffer, it means you have made a mistake in your shell's init file by | |
244 | setting the prompt unconditionally. (This init file's name may be | |
245 | @file{.bashrc}, @file{.profile}, @file{.cshrc}, @file{.shrc}, or various | |
246 | other things, depending on the shell you use.) The shell init file | |
247 | should set the prompt only if there already is a prompt. In csh, here | |
248 | is how to do it: | |
249 | ||
250 | @example | |
251 | if ($?prompt) set prompt = @dots{} | |
252 | @end example | |
253 | ||
254 | @noindent | |
255 | And here's how to do it in bash: | |
256 | ||
257 | @example | |
258 | if [ "$@{PS1+set@}" = set ] | |
259 | then PS1=@dots{} | |
260 | fi | |
261 | @end example | |
262 | ||
263 | There may well be other things that your shell's init file | |
264 | ought to do only for an interactive shell. You can use the same | |
265 | method to conditionalize them. | |
266 | ||
267 | The MS-DOS ``operating system'' does not support asynchronous | |
268 | subprocesses; to work around this lack, @kbd{M-x compile} runs the | |
269 | compilation command synchronously on MS-DOS. As a consequence, you must | |
270 | wait until the command finishes before you can do anything else in | |
271 | Emacs. @xref{MS-DOS}. | |
272 | ||
273 | @node Debuggers | |
274 | @section Running Debuggers Under Emacs | |
275 | @cindex debuggers | |
276 | @cindex GUD library | |
277 | @cindex GDB | |
278 | @cindex DBX | |
279 | @cindex SDB | |
280 | @cindex XDB | |
281 | @cindex Perldb | |
282 | @cindex JDB | |
283 | @cindex PDB | |
284 | ||
285 | @c Do you believe in GUD? | |
286 | The GUD (Grand Unified Debugger) library provides an interface to | |
287 | various symbolic debuggers from within Emacs. We recommend the debugger | |
288 | GDB, which is free software, but you can also run DBX, SDB or XDB if you | |
96110242 | 289 | have them. GUD can also serve as an interface to Perl's debugging |
6bf7aab6 | 290 | mode, the Python debugger PDB, and to JDB, the Java Debugger. |
6a27bff1 | 291 | @xref{Debugging,, The Lisp Debugger, elisp, the Emacs Lisp Reference Manual}, |
d952abde | 292 | for information on debugging Emacs Lisp programs. |
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293 | |
294 | @menu | |
295 | * Starting GUD:: How to start a debugger subprocess. | |
296 | * Debugger Operation:: Connection between the debugger and source buffers. | |
297 | * Commands of GUD:: Key bindings for common commands. | |
298 | * GUD Customization:: Defining your own commands for GUD. | |
c0d8ceaa | 299 | * GUD Tooltips:: Showing variable values by pointing with the mouse. |
f9ad161b RS |
300 | * GDB Graphical Interface:: An enhanced mode that uses GDB features to |
301 | implement a graphical debugging environment through | |
302 | Emacs. | |
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303 | @end menu |
304 | ||
305 | @node Starting GUD | |
306 | @subsection Starting GUD | |
307 | ||
308 | There are several commands for starting a debugger, each corresponding | |
309 | to a particular debugger program. | |
310 | ||
311 | @table @kbd | |
312 | @item M-x gdb @key{RET} @var{file} @key{RET} | |
313 | @findex gdb | |
96110242 NR |
314 | Run GDB as a subprocess of Emacs. If the variable |
315 | @code{gud-gdb-command-name} is ``gdb --annotate=3'' (the default | |
316 | value) then GDB starts as for @kbd{M-x gdba} below. If you want to | |
317 | GDB to start as in Emacs 21.3 and earlier then set | |
318 | @code{gud-gdb-command-name} to ``gdb --fullname''. In this case, the | |
319 | command creates a buffer for input and output to GDB, and switches to | |
320 | it. If a GDB buffer already exists, it just switches to that buffer. | |
6bf7aab6 | 321 | |
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322 | @item M-x gdba @key{RET} @var{file} @key{RET} |
323 | Run GDB as a subprocess of Emacs, providing a graphical interface | |
324 | to GDB features through Emacs. @xref{GDB Graphical Interface}. | |
325 | ||
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326 | @item M-x dbx @key{RET} @var{file} @key{RET} |
327 | @findex dbx | |
4125ceb0 | 328 | Similar, but run DBX instead of GDB. |
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329 | |
330 | @item M-x xdb @key{RET} @var{file} @key{RET} | |
331 | @findex xdb | |
332 | @vindex gud-xdb-directories | |
4125ceb0 | 333 | Similar, but run XDB instead of GDB. Use the variable |
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334 | @code{gud-xdb-directories} to specify directories to search for source |
335 | files. | |
336 | ||
337 | @item M-x sdb @key{RET} @var{file} @key{RET} | |
338 | @findex sdb | |
4125ceb0 | 339 | Similar, but run SDB instead of GDB. |
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340 | |
341 | Some versions of SDB do not mention source file names in their | |
342 | messages. When you use them, you need to have a valid tags table | |
343 | (@pxref{Tags}) in order for GUD to find functions in the source code. | |
344 | If you have not visited a tags table or the tags table doesn't list one | |
345 | of the functions, you get a message saying @samp{The sdb support | |
346 | requires a valid tags table to work}. If this happens, generate a valid | |
347 | tags table in the working directory and try again. | |
348 | ||
349 | @item M-x perldb @key{RET} @var{file} @key{RET} | |
350 | @findex perldb | |
351 | Run the Perl interpreter in debug mode to debug @var{file}, a Perl program. | |
352 | ||
353 | @item M-x jdb @key{RET} @var{file} @key{RET} | |
354 | @findex jdb | |
355 | Run the Java debugger to debug @var{file}. | |
356 | ||
357 | @item M-x pdb @key{RET} @var{file} @key{RET} | |
358 | @findex pdb | |
359 | Run the Python debugger to debug @var{file}. | |
360 | @end table | |
361 | ||
362 | Each of these commands takes one argument: a command line to invoke | |
363 | the debugger. In the simplest case, specify just the name of the | |
364 | executable file you want to debug. You may also use options that the | |
365 | debugger supports. However, shell wildcards and variables are not | |
366 | allowed. GUD assumes that the first argument not starting with a | |
367 | @samp{-} is the executable file name. | |
368 | ||
369 | Emacs can only run one debugger process at a time. | |
370 | ||
371 | @node Debugger Operation | |
372 | @subsection Debugger Operation | |
373 | ||
3605e23f | 374 | @cindex fringes, and current execution line in GUD |
6bf7aab6 DL |
375 | When you run a debugger with GUD, the debugger uses an Emacs buffer |
376 | for its ordinary input and output. This is called the GUD buffer. The | |
377 | debugger displays the source files of the program by visiting them in | |
378 | Emacs buffers. An arrow (@samp{=>}) in one of these buffers indicates | |
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379 | the current execution line.@footnote{Under a window system, the arrow |
380 | appears in the left fringe of the Emacs window.} Moving point in this | |
381 | buffer does not move the arrow. | |
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382 | |
383 | You can start editing these source files at any time in the buffers | |
58fa012d | 384 | that display them. The arrow is not part of the file's |
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385 | text; it appears only on the screen. If you do modify a source file, |
386 | keep in mind that inserting or deleting lines will throw off the arrow's | |
387 | positioning; GUD has no way of figuring out which line corresponded | |
388 | before your changes to the line number in a debugger message. Also, | |
389 | you'll typically have to recompile and restart the program for your | |
390 | changes to be reflected in the debugger's tables. | |
391 | ||
392 | If you wish, you can control your debugger process entirely through the | |
393 | debugger buffer, which uses a variant of Shell mode. All the usual | |
394 | commands for your debugger are available, and you can use the Shell mode | |
395 | history commands to repeat them. @xref{Shell Mode}. | |
396 | ||
397 | @node Commands of GUD | |
398 | @subsection Commands of GUD | |
399 | ||
400 | The GUD interaction buffer uses a variant of Shell mode, so the | |
401 | commands of Shell mode are available (@pxref{Shell Mode}). GUD mode | |
402 | also provides commands for setting and clearing breakpoints, for | |
403 | selecting stack frames, and for stepping through the program. These | |
404 | commands are available both in the GUD buffer and globally, but with | |
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405 | different key bindings. It also has its own toolbar from which you |
406 | can invoke the more common commands by clicking on the appropriate | |
407 | icon. This is particularly useful for repetitive commands like | |
408 | gud-next and gud-step and allows the user to hide the GUD buffer. | |
6bf7aab6 | 409 | |
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410 | The breakpoint commands are normally used in source file buffers, |
411 | because that is the easiest way to specify where to set or clear the | |
412 | breakpoint. Here's the global command to set a breakpoint: | |
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413 | |
414 | @table @kbd | |
415 | @item C-x @key{SPC} | |
416 | @kindex C-x SPC | |
417 | Set a breakpoint on the source line that point is on. | |
418 | @end table | |
419 | ||
420 | @kindex C-x C-a @r{(GUD)} | |
421 | Here are the other special commands provided by GUD. The keys | |
422 | starting with @kbd{C-c} are available only in the GUD interaction | |
423 | buffer. The key bindings that start with @kbd{C-x C-a} are available in | |
424 | the GUD interaction buffer and also in source files. | |
425 | ||
426 | @table @kbd | |
427 | @item C-c C-l | |
428 | @kindex C-c C-l @r{(GUD)} | |
429 | @itemx C-x C-a C-l | |
430 | @findex gud-refresh | |
431 | Display in another window the last line referred to in the GUD | |
432 | buffer (that is, the line indicated in the last location message). | |
433 | This runs the command @code{gud-refresh}. | |
434 | ||
435 | @item C-c C-s | |
436 | @kindex C-c C-s @r{(GUD)} | |
437 | @itemx C-x C-a C-s | |
438 | @findex gud-step | |
439 | Execute a single line of code (@code{gud-step}). If the line contains | |
440 | a function call, execution stops after entering the called function. | |
441 | ||
442 | @item C-c C-n | |
443 | @kindex C-c C-n @r{(GUD)} | |
444 | @itemx C-x C-a C-n | |
445 | @findex gud-next | |
446 | Execute a single line of code, stepping across entire function calls | |
447 | at full speed (@code{gud-next}). | |
448 | ||
449 | @item C-c C-i | |
450 | @kindex C-c C-i @r{(GUD)} | |
451 | @itemx C-x C-a C-i | |
452 | @findex gud-stepi | |
453 | Execute a single machine instruction (@code{gud-stepi}). | |
454 | ||
455 | @need 3000 | |
456 | @item C-c C-r | |
457 | @kindex C-c C-r @r{(GUD)} | |
458 | @itemx C-x C-a C-r | |
459 | @findex gud-cont | |
460 | Continue execution without specifying any stopping point. The program | |
461 | will run until it hits a breakpoint, terminates, or gets a signal that | |
462 | the debugger is checking for (@code{gud-cont}). | |
463 | ||
464 | @need 1000 | |
465 | @item C-c C-d | |
466 | @kindex C-c C-d @r{(GUD)} | |
467 | @itemx C-x C-a C-d | |
468 | @findex gud-remove | |
469 | Delete the breakpoint(s) on the current source line, if any | |
470 | (@code{gud-remove}). If you use this command in the GUD interaction | |
471 | buffer, it applies to the line where the program last stopped. | |
472 | ||
473 | @item C-c C-t | |
474 | @kindex C-c C-t @r{(GUD)} | |
475 | @itemx C-x C-a C-t | |
476 | @findex gud-tbreak | |
477 | Set a temporary breakpoint on the current source line, if any. | |
478 | If you use this command in the GUD interaction buffer, | |
479 | it applies to the line where the program last stopped. | |
480 | @end table | |
481 | ||
482 | The above commands are common to all supported debuggers. If you are | |
483 | using GDB or (some versions of) DBX, these additional commands are available: | |
484 | ||
485 | @table @kbd | |
486 | @item C-c < | |
487 | @kindex C-c < @r{(GUD)} | |
488 | @itemx C-x C-a < | |
489 | @findex gud-up | |
490 | Select the next enclosing stack frame (@code{gud-up}). This is | |
491 | equivalent to the @samp{up} command. | |
492 | ||
493 | @item C-c > | |
494 | @kindex C-c > @r{(GUD)} | |
495 | @itemx C-x C-a > | |
496 | @findex gud-down | |
497 | Select the next inner stack frame (@code{gud-down}). This is | |
498 | equivalent to the @samp{down} command. | |
499 | @end table | |
500 | ||
501 | If you are using GDB, these additional key bindings are available: | |
502 | ||
503 | @table @kbd | |
f9ad161b RS |
504 | @item C-c C-r |
505 | @kindex C-c C-r @r{(GUD)} | |
506 | @itemx C-x C-a C-r | |
507 | @findex gud-run | |
508 | Start execution of the program (@code{gud-run}). | |
509 | ||
510 | @item C-c C-u | |
511 | @kindex C-c C-u @r{(GUD)} | |
512 | @itemx C-x C-a C-u | |
513 | @findex gud-until | |
514 | Continue execution to the current line. The program will run until | |
515 | it hits a breakpoint, terminates, gets a signal that the debugger is | |
516 | checking for, or reaches the line on which the cursor currently sits | |
517 | (@code{gud-until}). | |
518 | ||
6bf7aab6 DL |
519 | @item @key{TAB} |
520 | @kindex TAB @r{(GUD)} | |
521 | @findex gud-gdb-complete-command | |
522 | With GDB, complete a symbol name (@code{gud-gdb-complete-command}). | |
523 | This key is available only in the GUD interaction buffer, and requires | |
524 | GDB versions 4.13 and later. | |
525 | ||
526 | @item C-c C-f | |
527 | @kindex C-c C-f @r{(GUD)} | |
528 | @itemx C-x C-a C-f | |
529 | @findex gud-finish | |
530 | Run the program until the selected stack frame returns (or until it | |
531 | stops for some other reason). | |
5b7fc395 | 532 | |
44fa0ae8 RS |
533 | @item C-x C-a C-j |
534 | @kindex C-x C-a C-j @r{(GUD)} | |
5b7fc395 | 535 | @findex gud-jump |
44fa0ae8 RS |
536 | Only useful in a source buffer, (@code{gud-jump}) transfers the |
537 | program's execution point to the current line. In other words, the | |
538 | next line that the program executes will be the one where you gave the | |
539 | command. If the new execution line is in a different function from | |
540 | the previously one, GDB prompts for confirmation since the results may | |
541 | be bizarre. See the GDB manual entry regarding @code{jump} for | |
542 | details. | |
6bf7aab6 DL |
543 | @end table |
544 | ||
8d66c08b NR |
545 | If you started GDB with the command @code{gdba}, you can click |
546 | @kbd{Mouse-1} on a line of the source buffer, in the fringe or display | |
547 | margin, to set a breakpoint there. If a breakpoint already exists on | |
548 | that line, this action will remove it. | |
549 | (@code{gdb-mouse-toggle-breakpoint}). | |
550 | ||
6bf7aab6 DL |
551 | These commands interpret a numeric argument as a repeat count, when |
552 | that makes sense. | |
553 | ||
554 | Because @key{TAB} serves as a completion command, you can't use it to | |
555 | enter a tab as input to the program you are debugging with GDB. | |
556 | Instead, type @kbd{C-q @key{TAB}} to enter a tab. | |
557 | ||
558 | @node GUD Customization | |
559 | @subsection GUD Customization | |
560 | ||
561 | @vindex gdb-mode-hook | |
562 | @vindex dbx-mode-hook | |
563 | @vindex sdb-mode-hook | |
564 | @vindex xdb-mode-hook | |
565 | @vindex perldb-mode-hook | |
566 | @vindex pdb-mode-hook | |
567 | @vindex jdb-mode-hook | |
568 | On startup, GUD runs one of the following hooks: @code{gdb-mode-hook}, | |
569 | if you are using GDB; @code{dbx-mode-hook}, if you are using DBX; | |
570 | @code{sdb-mode-hook}, if you are using SDB; @code{xdb-mode-hook}, if you | |
571 | are using XDB; @code{perldb-mode-hook}, for Perl debugging mode; | |
74b1aac1 | 572 | @code{pdb-mode-hook}, for PDB; @code{jdb-mode-hook}, for JDB. You can |
6bf7aab6 DL |
573 | use these hooks to define custom key bindings for the debugger |
574 | interaction buffer. @xref{Hooks}. | |
575 | ||
576 | Here is a convenient way to define a command that sends a particular | |
577 | command string to the debugger, and set up a key binding for it in the | |
578 | debugger interaction buffer: | |
579 | ||
580 | @findex gud-def | |
581 | @example | |
582 | (gud-def @var{function} @var{cmdstring} @var{binding} @var{docstring}) | |
583 | @end example | |
584 | ||
585 | This defines a command named @var{function} which sends | |
586 | @var{cmdstring} to the debugger process, and gives it the documentation | |
7fb4961c | 587 | string @var{docstring}. You can then use the command @var{function} in any |
6bf7aab6 DL |
588 | buffer. If @var{binding} is non-@code{nil}, @code{gud-def} also binds |
589 | the command to @kbd{C-c @var{binding}} in the GUD buffer's mode and to | |
590 | @kbd{C-x C-a @var{binding}} generally. | |
591 | ||
592 | The command string @var{cmdstring} may contain certain | |
593 | @samp{%}-sequences that stand for data to be filled in at the time | |
594 | @var{function} is called: | |
595 | ||
596 | @table @samp | |
597 | @item %f | |
598 | The name of the current source file. If the current buffer is the GUD | |
599 | buffer, then the ``current source file'' is the file that the program | |
600 | stopped in. | |
601 | @c This said, ``the name of the file the program counter was in at the last breakpoint.'' | |
602 | @c But I suspect it is really the last stop file. | |
603 | ||
604 | @item %l | |
605 | The number of the current source line. If the current buffer is the GUD | |
606 | buffer, then the ``current source line'' is the line that the program | |
607 | stopped in. | |
608 | ||
609 | @item %e | |
610 | The text of the C lvalue or function-call expression at or adjacent to point. | |
611 | ||
612 | @item %a | |
613 | The text of the hexadecimal address at or adjacent to point. | |
614 | ||
615 | @item %p | |
616 | The numeric argument of the called function, as a decimal number. If | |
617 | the command is used without a numeric argument, @samp{%p} stands for the | |
618 | empty string. | |
619 | ||
620 | If you don't use @samp{%p} in the command string, the command you define | |
621 | ignores any numeric argument. | |
622 | @end table | |
623 | ||
c0d8ceaa DL |
624 | @node GUD Tooltips |
625 | @subsection GUD Tooltips | |
626 | ||
627 | @cindex tooltips with GUD | |
628 | The Tooltip facility (@pxref{Tooltips}) provides support for GUD@. If | |
629 | GUD support is activated by customizing the @code{tooltip} group, | |
630 | variable values can be displayed in tooltips by pointing at them with | |
631 | the mouse in the GUD buffer or in source buffers with major modes in the | |
632 | customizable list @code{tooltip-gud-modes}. | |
633 | ||
f9ad161b RS |
634 | @node GDB Graphical Interface |
635 | @subsection GDB Graphical Interface | |
636 | ||
637 | @findex gdba | |
638 | The command @code{gdba} starts GDB using a graphical interface where | |
639 | you view and control the program's data using Emacs windows. You can | |
640 | still interact with GDB through the GUD buffer, but the point of this | |
641 | mode is that you can do it through menus and clicks, without needing | |
642 | to know GDB commands. | |
643 | ||
644 | @menu | |
96110242 | 645 | * Layout:: Control the number of displayed buffers. |
f9ad161b RS |
646 | * Breakpoints Buffer:: A breakpoint control panel. |
647 | * Stack Buffer:: Select a frame from the call stack. | |
8d66c08b | 648 | * Watch Expressions:: Monitor variable values in the speedbar. |
f9ad161b | 649 | * Other Buffers:: Input/output, locals, registers and assembler buffers. |
f9ad161b RS |
650 | @end menu |
651 | ||
96110242 NR |
652 | @node Layout |
653 | @subsubsection Layout | |
654 | @cindex GDB User Interface layout | |
655 | ||
656 | @findex gdb-many-windows | |
657 | @vindex gdb-many-windows | |
658 | ||
659 | If the variable @code{gdb-many-windows} is @code{nil} (the default | |
660 | value) then gdb just pops up the GUD buffer unless the variable | |
661 | @code{gdb-show-main} is non-@code{nil}. In this case it starts with | |
662 | two windows: one displaying the GUD buffer and the other with the | |
663 | source file with the main routine of the inferior. | |
664 | ||
665 | If @code{gdb-many-windows} is non-@code{nil}, regardless of the value of | |
666 | @code{gdb-show-main}, the layout below will appear unless | |
667 | @code{gdb-use-inferior-io-buffer} is @code{nil}. In this case the | |
668 | source buffer occupies the full width of the frame. | |
669 | ||
670 | @multitable @columnfractions .5 .5 | |
671 | @item GUD buffer (I/O of GDB) | |
672 | @tab Locals buffer | |
673 | @item | |
674 | @tab | |
675 | @item Source buffer | |
676 | @tab Input/Output (of inferior) buffer | |
677 | @item | |
678 | @tab | |
679 | @item Stack buffer | |
680 | @tab Breakpoints buffer | |
681 | @end multitable | |
682 | ||
683 | To toggle this layout, do @kbd{M-x gdb-many-windows}. | |
684 | ||
685 | @findex gdb-restore-windows | |
686 | If you change the window layout, for example, while editing and | |
687 | re-compiling your program, then you can restore it with the command | |
688 | @code{gdb-restore-windows}. | |
689 | ||
690 | You may also choose which additional buffers you want to display, | |
691 | either in the same frame or a different one. Select GDB-windows or | |
692 | GDB-Frames from the menu-bar under the heading GUD. If the menu-bar | |
693 | is unavailable, type @code{M-x | |
694 | gdb-display-@var{buffertype}-buffer} or @code{M-x | |
695 | gdb-frame-@var{buffertype}-buffer} respectively, where @var{buffertype} | |
696 | is the relevant buffer type e.g breakpoints. | |
697 | ||
f9ad161b RS |
698 | @node Breakpoints Buffer |
699 | @subsubsection Breakpoints Buffer | |
700 | ||
701 | The breakpoints buffer shows the existing breakpoints and watchpoints | |
702 | (@pxref{Breakpoints,,, gdb, The GNU debugger}). It has three special | |
703 | commands: | |
704 | ||
705 | @table @kbd | |
706 | @item @key{SPC} | |
707 | @kindex SPC @r{(GDB breakpoints buffer)} | |
708 | @findex gdb-toggle-breakpoint | |
709 | Enable/disable the breakpoint at the current line | |
710 | (@code{gdb-toggle-breakpoint}). On a graphical display, this changes | |
711 | the color of a bullet in the margin of the source buffer at the | |
712 | relevant line. This is red when the breakpoint is enabled and grey | |
713 | when it is disabled. Text-only terminals correspondingly display | |
714 | a @samp{B} or @samp{b}. | |
715 | ||
716 | @item @kbd{d} | |
717 | @kindex d @r{(GDB breakpoints buffer)} | |
718 | @findex gdb-delete-breakpoint | |
719 | Delete the breakpoint at the current line (@code{gdb-delete-breakpoint}). | |
720 | ||
721 | @item @key{RET} | |
722 | @kindex RET @r{(GDB breakpoints buffer)} | |
723 | @findex gdb-goto-breakpoint | |
724 | Display the file in the source buffer at the breakpoint specified at | |
725 | the current line (@code{gdb-goto-breakpoint}). Alternatively, click @kbd{Mouse-2} on the breakpoint that you wish to visit. | |
726 | @end table | |
727 | ||
728 | @node Stack Buffer | |
729 | @subsubsection Stack Buffer | |
730 | ||
731 | The stack buffer displays a @dfn{call stack}, with one line for each | |
732 | of the nested subroutine calls (@dfn{stack frames}) now active in the | |
733 | program. @xref{Backtrace,,info stack, gdb, The GNU debugger}. | |
734 | ||
735 | Move point to any frame in the stack and type @key{RET} to make it | |
736 | become the current frame (@code{gdb-frames-select}) and display the | |
737 | associated source in the source buffer. Alternatively, click | |
738 | @kbd{Mouse-2} to make the selected frame become the current one. If the | |
739 | locals buffer is displayed then its contents update to display the | |
740 | variables that are local to the new frame. | |
741 | ||
9b418429 NR |
742 | @node Watch Expressions |
743 | @subsubsection Watch Expressions | |
744 | @cindex Watching expressions in GDB | |
f9ad161b RS |
745 | |
746 | If you want to see how a variable changes each time your program stops | |
9b418429 NR |
747 | then place the cursor over the variable name and click on the watch |
748 | icon in the toolbar (@code{gud-watch}). | |
f9ad161b | 749 | |
8d66c08b NR |
750 | Each watch expression is displayed in the speedbar. Complex data |
751 | types, such as arrays, structures and unions are represented in a tree | |
752 | format. To expand or contract a complex data type, click @kbd{Mouse-2} | |
753 | on the tag to the left of the expression. | |
f9ad161b | 754 | |
9b418429 NR |
755 | @kindex RET @r{(GDB speedbar)} |
756 | @findex gdb-var-delete | |
8d66c08b | 757 | With the cursor over the root expression of a complex data type, type |
96110242 | 758 | @kbd{D} to delete it from the speedbar |
8d66c08b NR |
759 | (@code{gdb-var-delete}). |
760 | ||
761 | @findex gdb-edit-value | |
762 | With the cursor over a simple data type or an element of a complex | |
763 | data type which holds a value, type @key{RET} or click @kbd{Mouse-2} to edit | |
764 | its value. A prompt for a new value appears in the mini-buffer | |
765 | (@code{gdb-edit-value}). | |
766 | ||
a1a3a37a NR |
767 | If you set the variable @code{gdb-show-changed-values} to |
768 | non-@code{nil} (the default value), then Emacs will use | |
769 | font-lock-warning-face to display values that have recently changed in | |
770 | the speedbar. | |
8d66c08b NR |
771 | |
772 | If you set the variable @code{gdb-use-colon-colon-notation} to a | |
773 | non-@code{nil} value, then, in C, Emacs will use the | |
774 | FUNCTION::VARIABLE format to display variables in the speedbar. | |
a1a3a37a NR |
775 | Since this does not work for variables defined in compound statements, |
776 | the default value is @code{nil}. | |
f9ad161b RS |
777 | |
778 | @node Other Buffers | |
779 | @subsubsection Other Buffers | |
780 | ||
781 | @table @asis | |
782 | @item Input/Output Buffer | |
96110242 NR |
783 | If the variable @code{gdb-use-inferior-io-buffer} is non-@code{nil}, |
784 | the executable program that is being debugged takes its input and | |
f9ad161b RS |
785 | displays its output here. Some of the commands from shell mode are |
786 | available here. @xref{Shell Mode}. | |
787 | ||
788 | @item Locals Buffer | |
789 | The locals buffer displays the values of local variables of the | |
790 | current frame for simple data types (@pxref{Frame Info,,, gdb, The GNU | |
791 | debugger}). | |
792 | ||
793 | Arrays and structures display their type only. You must display them | |
9b418429 | 794 | separately to examine their values. @ref{Watch Expressions}. |
f9ad161b RS |
795 | |
796 | @item Registers Buffer | |
797 | The registers buffer displays the values held by the registers | |
798 | (@pxref{Registers,,, gdb, The GNU debugger}). | |
799 | ||
800 | @item Assembler Buffer | |
801 | The assembler buffer displays the current frame as machine code. An | |
802 | overlay arrow points to the current instruction and you can set and | |
803 | remove breakpoints as with the source buffer. Breakpoints also | |
804 | appear in the margin. | |
8d66c08b NR |
805 | |
806 | @item Threads Buffer | |
807 | ||
808 | The threads buffer displays a summary of all threads currently in your | |
809 | program.(@pxref{Threads,,, gdb, The GNU debugger}). Move point to | |
810 | any thread in the list and type @key{RET} to make it become the | |
811 | current thread (@code{gdb-threads-select}) and display the associated | |
812 | source in the source buffer. Alternatively, click @kbd{Mouse-2} to | |
813 | make the selected thread become the current one. | |
814 | ||
f9ad161b RS |
815 | @end table |
816 | ||
6bf7aab6 DL |
817 | @node Executing Lisp |
818 | @section Executing Lisp Expressions | |
819 | ||
820 | Emacs has several different major modes for Lisp and Scheme. They are | |
821 | the same in terms of editing commands, but differ in the commands for | |
822 | executing Lisp expressions. Each mode has its own purpose. | |
823 | ||
824 | @table @asis | |
825 | @item Emacs-Lisp mode | |
826 | The mode for editing source files of programs to run in Emacs Lisp. | |
827 | This mode defines @kbd{C-M-x} to evaluate the current defun. | |
828 | @xref{Lisp Libraries}. | |
829 | @item Lisp Interaction mode | |
830 | The mode for an interactive session with Emacs Lisp. It defines | |
831 | @kbd{C-j} to evaluate the sexp before point and insert its value in the | |
832 | buffer. @xref{Lisp Interaction}. | |
833 | @item Lisp mode | |
834 | The mode for editing source files of programs that run in Lisps other | |
835 | than Emacs Lisp. This mode defines @kbd{C-M-x} to send the current defun | |
836 | to an inferior Lisp process. @xref{External Lisp}. | |
837 | @item Inferior Lisp mode | |
838 | The mode for an interactive session with an inferior Lisp process. | |
839 | This mode combines the special features of Lisp mode and Shell mode | |
840 | (@pxref{Shell Mode}). | |
841 | @item Scheme mode | |
842 | Like Lisp mode but for Scheme programs. | |
843 | @item Inferior Scheme mode | |
844 | The mode for an interactive session with an inferior Scheme process. | |
845 | @end table | |
846 | ||
847 | Most editing commands for working with Lisp programs are in fact | |
848 | available globally. @xref{Programs}. | |
849 | ||
850 | @node Lisp Libraries | |
851 | @section Libraries of Lisp Code for Emacs | |
852 | @cindex libraries | |
853 | @cindex loading Lisp code | |
854 | ||
855 | Lisp code for Emacs editing commands is stored in files whose names | |
856 | conventionally end in @file{.el}. This ending tells Emacs to edit them in | |
857 | Emacs-Lisp mode (@pxref{Executing Lisp}). | |
858 | ||
859 | @findex load-file | |
860 | To execute a file of Emacs Lisp code, use @kbd{M-x load-file}. This | |
861 | command reads a file name using the minibuffer and then executes the | |
862 | contents of that file as Lisp code. It is not necessary to visit the | |
863 | file first; in any case, this command reads the file as found on disk, | |
864 | not text in an Emacs buffer. | |
865 | ||
866 | @findex load | |
867 | @findex load-library | |
868 | Once a file of Lisp code is installed in the Emacs Lisp library | |
869 | directories, users can load it using @kbd{M-x load-library}. Programs can | |
870 | load it by calling @code{load-library}, or with @code{load}, a more primitive | |
871 | function that is similar but accepts some additional arguments. | |
872 | ||
873 | @kbd{M-x load-library} differs from @kbd{M-x load-file} in that it | |
874 | searches a sequence of directories and tries three file names in each | |
875 | directory. Suppose your argument is @var{lib}; the three names are | |
876 | @file{@var{lib}.elc}, @file{@var{lib}.el}, and lastly just | |
877 | @file{@var{lib}}. If @file{@var{lib}.elc} exists, it is by convention | |
878 | the result of compiling @file{@var{lib}.el}; it is better to load the | |
879 | compiled file, since it will load and run faster. | |
880 | ||
881 | If @code{load-library} finds that @file{@var{lib}.el} is newer than | |
48dbca2c | 882 | @file{@var{lib}.elc} file, it issues a warning, because it's likely that |
6bf7aab6 DL |
883 | somebody made changes to the @file{.el} file and forgot to recompile |
884 | it. | |
885 | ||
886 | Because the argument to @code{load-library} is usually not in itself | |
887 | a valid file name, file name completion is not available. Indeed, when | |
888 | using this command, you usually do not know exactly what file name | |
889 | will be used. | |
890 | ||
891 | @vindex load-path | |
892 | The sequence of directories searched by @kbd{M-x load-library} is | |
893 | specified by the variable @code{load-path}, a list of strings that are | |
894 | directory names. The default value of the list contains the directory where | |
895 | the Lisp code for Emacs itself is stored. If you have libraries of | |
896 | your own, put them in a single directory and add that directory | |
897 | to @code{load-path}. @code{nil} in this list stands for the current default | |
898 | directory, but it is probably not a good idea to put @code{nil} in the | |
899 | list. If you find yourself wishing that @code{nil} were in the list, | |
900 | most likely what you really want to do is use @kbd{M-x load-file} | |
901 | this once. | |
902 | ||
903 | @cindex autoload | |
904 | Often you do not have to give any command to load a library, because | |
905 | the commands defined in the library are set up to @dfn{autoload} that | |
906 | library. Trying to run any of those commands calls @code{load} to load | |
907 | the library; this replaces the autoload definitions with the real ones | |
908 | from the library. | |
909 | ||
910 | @cindex byte code | |
911 | Emacs Lisp code can be compiled into byte-code which loads faster, | |
912 | takes up less space when loaded, and executes faster. @xref{Byte | |
913 | Compilation,, Byte Compilation, elisp, the Emacs Lisp Reference Manual}. | |
914 | By convention, the compiled code for a library goes in a separate file | |
915 | whose name consists of the library source file with @samp{c} appended. | |
916 | Thus, the compiled code for @file{foo.el} goes in @file{foo.elc}. | |
917 | That's why @code{load-library} searches for @samp{.elc} files first. | |
918 | ||
493c59e0 EZ |
919 | @vindex load-dangerous-libraries |
920 | @cindex Lisp files byte-compiled by XEmacs | |
a50c7a80 RS |
921 | By default, Emacs refuses to load compiled Lisp files which were |
922 | compiled with XEmacs, a modified versions of Emacs---they can cause | |
923 | Emacs to crash. Set the variable @code{load-dangerous-libraries} to | |
924 | @code{t} if you want to try loading them. | |
493c59e0 | 925 | |
6bf7aab6 DL |
926 | @node Lisp Eval |
927 | @section Evaluating Emacs-Lisp Expressions | |
928 | @cindex Emacs-Lisp mode | |
929 | @cindex mode, Emacs-Lisp | |
930 | ||
931 | @findex emacs-lisp-mode | |
932 | Lisp programs intended to be run in Emacs should be edited in | |
933 | Emacs-Lisp mode; this happens automatically for file names ending in | |
934 | @file{.el}. By contrast, Lisp mode itself is used for editing Lisp | |
935 | programs intended for other Lisp systems. To switch to Emacs-Lisp mode | |
936 | explicitly, use the command @kbd{M-x emacs-lisp-mode}. | |
937 | ||
938 | For testing of Lisp programs to run in Emacs, it is often useful to | |
939 | evaluate part of the program as it is found in the Emacs buffer. For | |
940 | example, after changing the text of a Lisp function definition, | |
941 | evaluating the definition installs the change for future calls to the | |
942 | function. Evaluation of Lisp expressions is also useful in any kind of | |
943 | editing, for invoking noninteractive functions (functions that are | |
944 | not commands). | |
945 | ||
946 | @table @kbd | |
947 | @item M-: | |
948 | Read a single Lisp expression in the minibuffer, evaluate it, and print | |
949 | the value in the echo area (@code{eval-expression}). | |
950 | @item C-x C-e | |
951 | Evaluate the Lisp expression before point, and print the value in the | |
952 | echo area (@code{eval-last-sexp}). | |
953 | @item C-M-x | |
954 | Evaluate the defun containing or after point, and print the value in | |
955 | the echo area (@code{eval-defun}). | |
956 | @item M-x eval-region | |
957 | Evaluate all the Lisp expressions in the region. | |
958 | @item M-x eval-current-buffer | |
959 | Evaluate all the Lisp expressions in the buffer. | |
960 | @end table | |
961 | ||
09041c4b | 962 | @ifinfo |
c668cdd0 EZ |
963 | @c This uses ``colon'' instead of a literal `:' because Info cannot |
964 | @c cope with a `:' in a menu | |
965 | @kindex M-@key{colon} | |
09041c4b EZ |
966 | @end ifinfo |
967 | @ifnotinfo | |
968 | @kindex M-: | |
969 | @end ifnotinfo | |
6bf7aab6 DL |
970 | @findex eval-expression |
971 | @kbd{M-:} (@code{eval-expression}) is the most basic command for evaluating | |
972 | a Lisp expression interactively. It reads the expression using the | |
973 | minibuffer, so you can execute any expression on a buffer regardless of | |
974 | what the buffer contains. When the expression is evaluated, the current | |
975 | buffer is once again the buffer that was current when @kbd{M-:} was | |
976 | typed. | |
977 | ||
978 | @kindex C-M-x @r{(Emacs-Lisp mode)} | |
979 | @findex eval-defun | |
980 | In Emacs-Lisp mode, the key @kbd{C-M-x} is bound to the command | |
981 | @code{eval-defun}, which parses the defun containing or following point | |
982 | as a Lisp expression and evaluates it. The value is printed in the echo | |
983 | area. This command is convenient for installing in the Lisp environment | |
984 | changes that you have just made in the text of a function definition. | |
985 | ||
986 | @kbd{C-M-x} treats @code{defvar} expressions specially. Normally, | |
987 | evaluating a @code{defvar} expression does nothing if the variable it | |
988 | defines already has a value. But @kbd{C-M-x} unconditionally resets the | |
989 | variable to the initial value specified in the @code{defvar} expression. | |
9c8599ca | 990 | @code{defcustom} expressions are treated similarly. |
6bf7aab6 DL |
991 | This special feature is convenient for debugging Lisp programs. |
992 | ||
993 | @kindex C-x C-e | |
994 | @findex eval-last-sexp | |
995 | The command @kbd{C-x C-e} (@code{eval-last-sexp}) evaluates the Lisp | |
996 | expression preceding point in the buffer, and displays the value in the | |
997 | echo area. It is available in all major modes, not just Emacs-Lisp | |
998 | mode. It does not treat @code{defvar} specially. | |
999 | ||
1000 | If @kbd{C-M-x}, @kbd{C-x C-e}, or @kbd{M-:} is given a numeric | |
1001 | argument, it inserts the value into the current buffer at point, rather | |
1002 | than displaying it in the echo area. The argument's value does not | |
1003 | matter. | |
1004 | ||
1005 | @findex eval-region | |
1006 | @findex eval-current-buffer | |
1007 | The most general command for evaluating Lisp expressions from a buffer | |
1008 | is @code{eval-region}. @kbd{M-x eval-region} parses the text of the | |
1009 | region as one or more Lisp expressions, evaluating them one by one. | |
1010 | @kbd{M-x eval-current-buffer} is similar but evaluates the entire | |
1011 | buffer. This is a reasonable way to install the contents of a file of | |
58fa012d | 1012 | Lisp code that you are ready to test. Later, as you find bugs and |
6bf7aab6 DL |
1013 | change individual functions, use @kbd{C-M-x} on each function that you |
1014 | change. This keeps the Lisp world in step with the source file. | |
1015 | ||
9c8599ca DL |
1016 | @vindex eval-expression-print-level |
1017 | @vindex eval-expression-print-length | |
1018 | @vindex eval-expression-debug-on-error | |
1019 | The customizable variables @code{eval-expression-print-level} and | |
1020 | @code{eval-expression-print-length} control the maximum depth and length | |
1021 | of lists to print in the result of the evaluation commands before | |
1022 | abbreviating them. @code{eval-expression-debug-on-error} controls | |
1023 | whether evaluation errors invoke the debugger when these commands are | |
1024 | used. | |
1025 | ||
6bf7aab6 DL |
1026 | @node Lisp Interaction |
1027 | @section Lisp Interaction Buffers | |
1028 | ||
1029 | The buffer @samp{*scratch*} which is selected when Emacs starts up is | |
1030 | provided for evaluating Lisp expressions interactively inside Emacs. | |
1031 | ||
1032 | The simplest way to use the @samp{*scratch*} buffer is to insert Lisp | |
1033 | expressions and type @kbd{C-j} after each expression. This command | |
1034 | reads the Lisp expression before point, evaluates it, and inserts the | |
1035 | value in printed representation before point. The result is a complete | |
1036 | typescript of the expressions you have evaluated and their values. | |
1037 | ||
1038 | The @samp{*scratch*} buffer's major mode is Lisp Interaction mode, which | |
1039 | is the same as Emacs-Lisp mode except for the binding of @kbd{C-j}. | |
1040 | ||
1041 | @findex lisp-interaction-mode | |
1042 | The rationale for this feature is that Emacs must have a buffer when | |
1043 | it starts up, but that buffer is not useful for editing files since a | |
1044 | new buffer is made for every file that you visit. The Lisp interpreter | |
1045 | typescript is the most useful thing I can think of for the initial | |
1046 | buffer to do. Type @kbd{M-x lisp-interaction-mode} to put the current | |
1047 | buffer in Lisp Interaction mode. | |
1048 | ||
1049 | @findex ielm | |
1050 | An alternative way of evaluating Emacs Lisp expressions interactively | |
1051 | is to use Inferior Emacs-Lisp mode, which provides an interface rather | |
1052 | like Shell mode (@pxref{Shell Mode}) for evaluating Emacs Lisp | |
1053 | expressions. Type @kbd{M-x ielm} to create an @samp{*ielm*} buffer | |
1054 | which uses this mode. | |
1055 | ||
1056 | @node External Lisp | |
1057 | @section Running an External Lisp | |
1058 | ||
1059 | Emacs has facilities for running programs in other Lisp systems. You can | |
1060 | run a Lisp process as an inferior of Emacs, and pass expressions to it to | |
1061 | be evaluated. You can also pass changed function definitions directly from | |
1062 | the Emacs buffers in which you edit the Lisp programs to the inferior Lisp | |
1063 | process. | |
1064 | ||
1065 | @findex run-lisp | |
1066 | @vindex inferior-lisp-program | |
1067 | @kindex C-x C-z | |
1068 | To run an inferior Lisp process, type @kbd{M-x run-lisp}. This runs | |
1069 | the program named @code{lisp}, the same program you would run by typing | |
1070 | @code{lisp} as a shell command, with both input and output going through | |
1071 | an Emacs buffer named @samp{*lisp*}. That is to say, any ``terminal | |
1072 | output'' from Lisp will go into the buffer, advancing point, and any | |
1073 | ``terminal input'' for Lisp comes from text in the buffer. (You can | |
1074 | change the name of the Lisp executable file by setting the variable | |
1075 | @code{inferior-lisp-program}.) | |
1076 | ||
1077 | To give input to Lisp, go to the end of the buffer and type the input, | |
1078 | terminated by @key{RET}. The @samp{*lisp*} buffer is in Inferior Lisp | |
1079 | mode, which combines the special characteristics of Lisp mode with most | |
1080 | of the features of Shell mode (@pxref{Shell Mode}). The definition of | |
1081 | @key{RET} to send a line to a subprocess is one of the features of Shell | |
1082 | mode. | |
1083 | ||
1084 | @findex lisp-mode | |
1085 | For the source files of programs to run in external Lisps, use Lisp | |
1086 | mode. This mode can be selected with @kbd{M-x lisp-mode}, and is used | |
1087 | automatically for files whose names end in @file{.l}, @file{.lsp}, or | |
1088 | @file{.lisp}, as most Lisp systems usually expect. | |
1089 | ||
1090 | @kindex C-M-x @r{(Lisp mode)} | |
1091 | @findex lisp-eval-defun | |
1092 | When you edit a function in a Lisp program you are running, the easiest | |
1093 | way to send the changed definition to the inferior Lisp process is the key | |
1094 | @kbd{C-M-x}. In Lisp mode, this runs the function @code{lisp-eval-defun}, | |
1095 | which finds the defun around or following point and sends it as input to | |
1096 | the Lisp process. (Emacs can send input to any inferior process regardless | |
1097 | of what buffer is current.) | |
1098 | ||
1099 | Contrast the meanings of @kbd{C-M-x} in Lisp mode (for editing programs | |
1100 | to be run in another Lisp system) and Emacs-Lisp mode (for editing Lisp | |
1101 | programs to be run in Emacs): in both modes it has the effect of installing | |
1102 | the function definition that point is in, but the way of doing so is | |
1103 | different according to where the relevant Lisp environment is found. | |
1104 | @xref{Executing Lisp}. | |
ab5796a9 MB |
1105 | |
1106 | @ignore | |
1107 | arch-tag: 9c3c2f71-b332-4144-8500-3ff9945a50ed | |
1108 | @end ignore |