@c This is part of the Emacs manual.
-@c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2011
-@c Free Software Foundation, Inc.
+@c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2013 Free Software
+@c Foundation, Inc.
@c See file emacs.texi for copying conditions.
-@node Building, Maintaining, Programs, Top
+@node Building
@chapter Compiling and Testing Programs
@cindex building programs
@cindex program building
* Executing Lisp:: Various modes for editing Lisp programs,
with different facilities for running
the Lisp programs.
-* Libraries: Lisp Libraries. Creating Lisp programs to run in Emacs.
+* Libraries: Lisp Libraries. How Lisp programs are loaded into Emacs.
* Eval: Lisp Eval. Executing a single Lisp expression in Emacs.
* Interaction: Lisp Interaction. Executing Lisp in an Emacs buffer.
* External Lisp:: Communicating through Emacs with a separate Lisp.
@cindex compilation errors
@cindex error log
- Emacs can run compilers for languages such as C and Fortran as
-inferior processes, feeding the compilation log into an Emacs buffer.
-It can also parse the error messages and show you where the errors
-occurred.
+ Emacs can run compilers for languages such as C and Fortran, feeding
+the compilation log into an Emacs buffer. It can also parse the error
+messages and show you where the errors occurred.
@table @kbd
@item M-x compile
Run a compiler asynchronously under Emacs, with error messages going to
-the @samp{*compilation*} buffer.
+the @file{*compilation*} buffer.
@item M-x recompile
Invoke a compiler with the same command as in the last invocation of
@kbd{M-x compile}.
@findex compile
To run @code{make} or another compilation command, type @kbd{M-x
compile}. This reads a shell command line using the minibuffer, and
-then executes the command in an inferior shell, putting output in the
-buffer named @samp{*compilation*}. The current buffer's default
-directory is used as the working directory for the execution of the
-command; normally, therefore, compilation takes place in this
-directory.
+then executes the command by running a shell as a subprocess (or
+@dfn{inferior process}) of Emacs. The output is inserted in a buffer
+named @file{*compilation*}. The current buffer's default directory is
+used as the working directory for the execution of the command;
+normally, therefore, compilation takes place in this directory.
@vindex compile-command
The default compilation command is @samp{make -k}, which is usually
type @kbd{M-x compile}. A file can also specify a file-local value
for @code{compile-command} (@pxref{File Variables}).
- Starting a compilation displays the @samp{*compilation*} buffer in
+ Starting a compilation displays the @file{*compilation*} buffer in
another window but does not select it. While the compilation is
running, the word @samp{run} is shown in the major mode indicator for
-the @samp{*compilation*} buffer, and the word @samp{Compiling} appears
-in all mode lines. You do not have to keep the @samp{*compilation*}
+the @file{*compilation*} buffer, and the word @samp{Compiling} appears
+in all mode lines. You do not have to keep the @file{*compilation*}
buffer visible while compilation is running; it continues in any case.
When the compilation ends, for whatever reason, the mode line of the
-@samp{*compilation*} buffer changes to say @samp{exit} (followed by
+@file{*compilation*} buffer changes to say @samp{exit} (followed by
the exit code: @samp{[0]} for a normal exit), or @samp{signal} (if a
signal terminated the process).
If you want to watch the compilation transcript as it appears,
-switch to the @samp{*compilation*} buffer and move point to the end of
+switch to the @file{*compilation*} buffer and move point to the end of
the buffer. When point is at the end, new compilation output is
inserted above point, which remains at the end. Otherwise, point
remains fixed while compilation output is added at the end of the
@cindex compilation buffer, keeping point at end
@vindex compilation-scroll-output
If you change the variable @code{compilation-scroll-output} to a
-non-@code{nil} value, the @samp{*compilation*} buffer scrolls
+non-@code{nil} value, the @file{*compilation*} buffer scrolls
automatically to follow the output. If the value is
@code{first-error}, scrolling stops when the first error appears,
leaving point at that error. For any other non-@code{nil} value,
To rerun the last compilation with the same command, type @kbd{M-x
recompile}. This reuses the compilation command from the last
invocation of @kbd{M-x compile}. It also reuses the
-@samp{*compilation*} buffer and starts the compilation in its default
+@file{*compilation*} buffer and starts the compilation in its default
directory, which is the directory in which the previous compilation
was started.
@findex kill-compilation
+@vindex compilation-always-kill
Starting a new compilation also kills any compilation already
-running in @samp{*compilation*}, as the buffer can only handle one
+running in @file{*compilation*}, as the buffer can only handle one
compilation at any time. However, @kbd{M-x compile} asks for
-confirmation before actually killing a compilation that is running.
-You can also kill the compilation process with @kbd{M-x
+confirmation before actually killing a compilation that is running; to
+always automatically kill the compilation without asking, change the
+variable @code{compilation-always-kill} to @code{t}. You can also
+kill a compilation process with the command @kbd{M-x
kill-compilation}.
To run two compilations at once, start the first one, then rename
-the @samp{*compilation*} buffer (perhaps using @code{rename-uniquely};
+the @file{*compilation*} buffer (perhaps using @code{rename-uniquely};
@pxref{Misc Buffer}), then switch buffers and start the other
-compilation. This will create a new @samp{*compilation*} buffer.
+compilation. This will create a new @file{*compilation*} buffer.
@vindex compilation-environment
You can control the environment passed to the compilation command
@cindex Compilation mode
@cindex mode, Compilation
@cindex locus
- The @samp{*compilation*} buffer uses a major mode called Compilation
+ The @file{*compilation*} buffer uses a major mode called Compilation
mode. Compilation mode turns each error message in the buffer into a
hyperlink; you can move point to it and type @key{RET}, or click on it
with the mouse (@pxref{Mouse References}), to visit the @dfn{locus} of
If you change the variable
@code{compilation-auto-jump-to-first-error} to a non-@code{nil} value,
Emacs automatically visits the locus of the first error message that
-appears in the @samp{*compilation*} buffer.
+appears in the @file{*compilation*} buffer.
Compilation mode provides the following additional commands. These
-commands can also be used in @samp{*grep*} buffers, where the
+commands can also be used in @file{*grep*} buffers, where the
hyperlinks are search matches rather than error messages (@pxref{Grep
Searching}).
visits the locus of the first error message. Each subsequent
@w{@kbd{C-x `}} visits the next error, in a similar fashion. If you
visit a specific error with @key{RET} or a mouse click in the
-@samp{*compilation*} buffer, subsequent @w{@kbd{C-x `}} commands
+@file{*compilation*} buffer, subsequent @w{@kbd{C-x `}} commands
advance from there. When @w{@kbd{C-x `}} finds no more error messages
to visit, it signals an error. @w{@kbd{C-u C-x `}} starts again from
the beginning of the compilation buffer, and visits the first locus.
through errors in the opposite direction.
The @code{next-error} and @code{previous-error} commands don't just
-act on the errors or matches listed in @samp{*compilation*} and
-@samp{*grep*} buffers; they also know how to iterate through error or
+act on the errors or matches listed in @file{*compilation*} and
+@file{*grep*} buffers; they also know how to iterate through error or
match lists produced by other commands, such as @kbd{M-x occur}
(@pxref{Other Repeating Search}). If you are already in a buffer
containing error messages or matches, those are the ones that are
is determined by the variable @code{next-error-highlight}.
@vindex compilation-context-lines
- If the @samp{*compilation*} buffer is shown in a window with a left
+ If the @file{*compilation*} buffer is shown in a window with a left
fringe (@pxref{Fringes}), the locus-visiting commands put an arrow in
the fringe, pointing to the current error message. If the window has
-no left fringe, such as on a text-only terminal, these commands scroll
-the window so that the current message is at the top of the window.
-If you change the variable @code{compilation-context-lines} to an
-integer value @var{n}, these commands scroll the window so that the
-current error message is @var{n} lines from the top, whether or not
-there is a fringe; the default value, @code{nil}, gives the behavior
-described above.
+no left fringe, such as on a text terminal, these commands scroll the
+window so that the current message is at the top of the window. If
+you change the variable @code{compilation-context-lines} to an integer
+value @var{n}, these commands scroll the window so that the current
+error message is @var{n} lines from the top, whether or not there is a
+fringe; the default value, @code{nil}, gives the behavior described
+above.
@vindex compilation-error-regexp-alist
@vindex grep-regexp-alist
@findex next-error-follow-minor-mode
You can type @kbd{C-c C-f} to toggle Next Error Follow mode. In
this minor mode, ordinary cursor motion in the compilation buffer
-automatically updates the source buffer, i.e.@: moving the cursor over
+automatically updates the source buffer, i.e., moving the cursor over
an error message causes the locus of that error to be displayed.
The features of Compilation mode are also available in a minor mode
command, but specifies the option for a noninteractive shell. This
means, in particular, that the shell should start with no prompt. If
you find your usual shell prompt making an unsightly appearance in the
-@samp{*compilation*} buffer, it means you have made a mistake in your
+@file{*compilation*} buffer, it means you have made a mistake in your
shell's init file by setting the prompt unconditionally. (This init
file may be named @file{.bashrc}, @file{.profile}, @file{.cshrc},
@file{.shrc}, etc., depending on what shell you use.) The shell init
@ifnottex
On the MS-DOS ``operating system'', asynchronous subprocesses are
not supported, so @kbd{M-x compile} runs the compilation command
-synchronously (i.e.@: you must wait until the command finishes before
+synchronously (i.e., you must wait until the command finishes before
you can do anything else in Emacs). @xref{MS-DOS}.
@end ifnottex
Just as you can run a compiler from Emacs and then visit the lines
with compilation errors, you can also run @command{grep} and then
visit the lines on which matches were found. This works by treating
-the matches reported by @command{grep} as if they were ``errors.''
+the matches reported by @command{grep} as if they were ``errors''.
The output buffer uses Grep mode, which is a variant of Compilation
mode (@pxref{Compilation Mode}).
@item M-x grep
@itemx M-x lgrep
Run @command{grep} asynchronously under Emacs, listing matching lines in
-the buffer named @samp{*grep*}.
+the buffer named @file{*grep*}.
@item M-x grep-find
@itemx M-x find-grep
@itemx M-x rgrep
Run @command{grep} via @code{find}, and collect output in the
-@samp{*grep*} buffer.
+@file{*grep*} buffer.
@item M-x zrgrep
-Run @code{zgrep} and collect output in the @samp{*grep*} buffer.
+Run @code{zgrep} and collect output in the @file{*grep*} buffer.
@item M-x kill-grep
Kill the running @command{grep} subprocess.
@end table
grep -nH -e foo *.el | grep bar | grep toto
@end example
- The output from @command{grep} goes in the @samp{*grep*} buffer. You
+ The output from @command{grep} goes in the @file{*grep*} buffer. You
can find the corresponding lines in the original files using @w{@kbd{C-x
`}}, @key{RET}, and so forth, just like compilation errors.
Flymake mode is a minor mode that performs on-the-fly syntax
checking for many programming and markup languages, including C, C++,
-Perl, HTML, and @TeX{}/La@TeX{}. It is somewhat analogous to Flyspell
+Perl, HTML, and @TeX{}/@LaTeX{}. It is somewhat analogous to Flyspell
mode, which performs spell checking for ordinary human languages in a
similar fashion (@pxref{Spelling}). As you edit a file, Flymake mode
runs an appropriate syntax checking tool in the background, using a
C/C++ files this is usually the C compiler. Flymake can also use
build tools such as @code{make} for checking complicated projects.
- To enable Flymake mode, type @kbd{M-x flymake-mode}. You can go to
-the errors found by Flymake mode with @kbd{M-x
-flymake-goto-next-error} and @kbd{M-x flymake-goto-prev-error}. To
-display any error messages associated with the current line, use
-@kbd{M-x flymake-display-err-menu-for-current-line}.
+ To enable Flymake mode, type @kbd{M-x flymake-mode}. You can jump
+to the errors that it finds by using @kbd{M-x flymake-goto-next-error}
+and @kbd{M-x flymake-goto-prev-error}. To display any error messages
+associated with the current line, type @kbd{M-x
+flymake-display-err-menu-for-current-line}.
For more details about using Flymake,
@ifnottex
* Commands of GUD:: Key bindings for common commands.
* GUD Customization:: Defining your own commands for GUD.
* GDB Graphical Interface:: An enhanced mode that uses GDB features to
- implement a graphical debugging environment through
- Emacs.
+ implement a graphical debugging environment.
@end menu
@node Starting GUD
@kbd{M-x gud-gdb} and other commands listed in
@iftex
the preceding section.
-@end iftext
+@end iftex
@ifnottex
@ref{Starting GUD}.
@end ifnottex
commands to repeat them.
@iftex
See the next section
-@end iftext
+@end iftex
@ifnottex
@xref{Commands of GUD},
@end ifnottex
As you debug a program, Emacs displays the relevant source files by
visiting them in Emacs buffers, with an arrow in the left fringe
-indicating the current execution line. (On a text-only terminal, the
-arrow appears as @samp{=>}, overlaid on the first two text columns.)
-Moving point in such a buffer does not move the arrow. You are free
-to edit these source files, but note that inserting or deleting lines
-will throw off the arrow's positioning, as Emacs has no way to figure
-out which edited source line corresponds to the line reported by the
+indicating the current execution line. (On a text terminal, the arrow
+appears as @samp{=>}, overlaid on the first two text columns.) Moving
+point in such a buffer does not move the arrow. You are free to edit
+these source files, but note that inserting or deleting lines will
+throw off the arrow's positioning, as Emacs has no way to figure out
+which edited source line corresponds to the line reported by the
debugger subprocess. To update this information, you typically have
to recompile and restart the program.
@findex gud-tooltip-mode
@vindex gud-tooltip-echo-area
GUD Tooltip mode is a global minor mode that adds tooltip support to
-GUD. To toggle this mode, type @kbd{M-x gud-tooltip-mode}. It is
+GUD@. To toggle this mode, type @kbd{M-x gud-tooltip-mode}. It is
disabled by default. If enabled, you can move the mouse cursor over a
-variable to show its value in a tooltip (@pxref{Tooltips}); this takes
-effect in the GUD interaction buffer, and in all source buffers with
-major modes listed in the variable @code{gud-tooltip-modes}. If the
-variable @code{gud-tooltip-echo-area} is non-@code{nil}, values are
-shown in the echo area instead of a tooltip.
-
- When using GUD Tooltip mode with @kbd{M-x gud-gdb}, you should note
-that displaying an expression's value in GDB can sometimes expand a
-macro, potentially causing side effects in the debugged program. If
-you use the @kbd{M-x gdb} interface, this problem does not occur, as
-there is special code to avoid side-effects; furthermore, you can
-display macro definitions associated with an identifier when the
-program is not executing.
+variable, a function, or a macro (collectively called
+@dfn{identifiers}) to show their values in tooltips
+(@pxref{Tooltips}). Alternatively, mark an identifier or an
+expression by dragging the mouse over it, then leave the mouse in the
+marked area to have the value of the expression displayed in a
+tooltip. The GUD Tooltip mode takes effect in the GUD interaction
+buffer, and in all source buffers with major modes listed in the
+variable @code{gud-tooltip-modes}. If the variable
+@code{gud-tooltip-echo-area} is non-@code{nil}, or if you turned off
+the tooltip mode, values are shown in the echo area instead of a
+tooltip.
+
+ When using GUD Tooltip mode with @kbd{M-x gud-gdb}, displaying an
+expression's value in GDB can sometimes expand a macro, potentially
+causing side effects in the debugged program. For that reason, using
+tooltips in @code{gud-gdb} is disabled. If you use the @kbd{M-x gdb}
+interface, this problem does not occur, as there is special code to
+avoid side-effects; furthermore, you can display macro definitions
+associated with an identifier when the program is not executing.
@node Commands of GUD
@subsection Commands of GUD
@kbd{C-x @key{SPC}} (@code{gud-break}), when called in a source
buffer, sets a debugger breakpoint on the current source line. This
-command is available only after starting GUD. If you call it in a
+command is available only after starting GUD@. If you call it in a
buffer that is not associated with any debugger subprocess, it signals
a error.
that makes sense.
Because @key{TAB} serves as a completion command, you can't use it to
-enter a tab as input to the program you are debugging with GDB.
+enter a tab as input to the program you are debugging with GDB@.
Instead, type @kbd{C-q @key{TAB}} to enter a tab.
@node GUD Customization
you are using DBX; @code{sdb-mode-hook}, if you are using SDB;
@code{xdb-mode-hook}, if you are using XDB; @code{perldb-mode-hook},
for Perl debugging mode; @code{pdb-mode-hook}, for PDB;
-@code{jdb-mode-hook}, for JDB. @xref{Hooks}.
+@code{jdb-mode-hook}, for JDB@. @xref{Hooks}.
The @code{gud-def} Lisp macro (@pxref{Defining Macros,,, elisp, the
Emacs Lisp Reference Manual}) provides a convenient way to define an
@end group
@end smallexample
- However, if @code{gdb-use-separate-io-buffer} is @code{nil}, the I/O
-buffer does not appear and the primary source buffer occupies the full
-width of the frame.
-
@findex gdb-restore-windows
@findex gdb-many-windows
If you ever change the window layout, you can restore the ``many
enables or disables an existing breakpoint; a breakpoint that is
disabled, but not unset, is indicated by a gray dot.
- On a text-only terminal, or when fringes are disabled, enabled
+ On a text terminal, or when fringes are disabled, enabled
breakpoints are indicated with a @samp{B} character in the left margin
of the window. Disabled breakpoints are indicated with @samp{b}.
(The margin is only displayed if a breakpoint is present.)
@findex gdb-frames-select
On graphical displays, the selected stack frame is indicated by an
-arrow in the fringe. On text-only terminals, or when fringes are
-disabled, the selected stack frame is displayed in reverse contrast.
-To select a stack frame, move point in its line and type @key{RET}
+arrow in the fringe. On text terminals, or when fringes are disabled,
+the selected stack frame is displayed in reverse contrast. To select
+a stack frame, move point in its line and type @key{RET}
(@code{gdb-frames-select}), or click @kbd{Mouse-2} on it. Doing so
also updates the Locals buffer
@ifnottex
@code{gdb-switch-reasons} to select the stop reasons which will cause
a thread switch.
-@vindex gdb-stopped-hooks
- The variable @code{gdb-stopped-hooks} allows you to execute your
+@vindex gdb-stopped-functions
+ The variable @code{gdb-stopped-functions} allows you to execute your
functions whenever some thread stops.
In non-stop mode, you can switch between different modes for GUD
@node Executing Lisp
@section Executing Lisp Expressions
- Emacs has several different major modes for Lisp and Scheme. They are
-the same in terms of editing commands, but differ in the commands for
-executing Lisp expressions. Each mode has its own purpose.
+ Emacs has major modes for several variants of Lisp. They use the
+same editing commands as other programming language modes
+(@pxref{Programs}). In addition, they provide special commands for
+executing Lisp expressions.
@table @asis
-@item Emacs-Lisp mode
-The mode for editing source files of programs to run in Emacs Lisp.
-This mode defines @kbd{C-M-x} to evaluate the current defun.
-@xref{Lisp Libraries}.
+@item Emacs Lisp mode
+The mode for editing Emacs Lisp source files. It defines @kbd{C-M-x}
+to evaluate the current top-level Lisp expression. @xref{Lisp Eval}.
+
@item Lisp Interaction mode
-The mode for an interactive session with Emacs Lisp. It defines
-@kbd{C-j} to evaluate the sexp before point and insert its value in the
+The mode for an interactive Emacs Lisp session. It defines @kbd{C-j}
+to evaluate the expression before point and insert its value in the
buffer. @xref{Lisp Interaction}.
+
@item Lisp mode
The mode for editing source files of programs that run in Lisps other
-than Emacs Lisp. This mode defines @kbd{C-M-x} to send the current defun
-to an inferior Lisp process. @xref{External Lisp}.
+than Emacs Lisp. It defines @kbd{C-M-x} to evaluate the current
+top-level expression in an external Lisp. @xref{External Lisp}.
+
@item Inferior Lisp mode
-The mode for an interactive session with an inferior Lisp process.
-This mode combines the special features of Lisp mode and Shell mode
-(@pxref{Shell Mode}).
+The mode for an interactive session with an external Lisp which is
+being run as a subprocess (or @dfn{inferior process}) of Emacs.
+@ifnottex
+@xref{External Lisp}.
+@end ifnottex
+
@item Scheme mode
-Like Lisp mode but for Scheme programs.
+Like Lisp mode, but for Scheme programs.
+
@item Inferior Scheme mode
-The mode for an interactive session with an inferior Scheme process.
+Like Inferior Lisp mode, but for Scheme.
@end table
- Most editing commands for working with Lisp programs are in fact
-available globally. @xref{Programs}.
-
@node Lisp Libraries
@section Libraries of Lisp Code for Emacs
@cindex libraries
@cindex loading Lisp code
- Lisp code for Emacs editing commands is stored in files whose names
-conventionally end in @file{.el}. This ending tells Emacs to edit them in
-Emacs-Lisp mode (@pxref{Executing Lisp}).
+ Emacs Lisp code is stored in files whose names conventionally end in
+@file{.el}. Such files are automatically visited in Emacs Lisp mode.
@cindex byte code
Emacs Lisp code can be compiled into byte-code, which loads faster,
-takes up less space, and executes faster. @xref{Byte Compilation,,
-Byte Compilation, elisp, the Emacs Lisp Reference Manual}. By
-convention, the compiled code for a library goes in a separate file
-whose name ends in @samp{.elc}. Thus, the compiled code for
-@file{foo.el} goes in @file{foo.elc}.
+takes up less space, and executes faster. By convention, compiled
+Emacs Lisp code goes in a separate file whose name ends in
+@samp{.elc}. For example, the compiled code for @file{foo.el} goes in
+@file{foo.elc}. @xref{Byte Compilation,, Byte Compilation, elisp, the
+Emacs Lisp Reference Manual}.
@findex load-file
- To execute a file of Emacs Lisp code, use @kbd{M-x load-file}. This
-command reads a file name using the minibuffer and then executes the
-contents of that file as Lisp code. It is not necessary to visit the
-file first; in any case, this command reads the file as found on disk,
-not text in an Emacs buffer.
+ To @dfn{load} an Emacs Lisp file, type @kbd{M-x load-file}. This
+command reads a file name using the minibuffer, and executes the
+contents of that file as Emacs Lisp code. It is not necessary to
+visit the file first; this command reads the file directly from disk,
+not from an existing Emacs buffer.
@findex load
@findex load-library
- Once a file of Lisp code is installed in the Emacs Lisp library
-directories, users can load it using @kbd{M-x load-library}. Programs
-can load it by calling @code{load}, a more primitive function that is
-similar but accepts some additional arguments.
-
- @kbd{M-x load-library} differs from @kbd{M-x load-file} in that it
-searches a sequence of directories and tries three file names in each
-directory. Suppose your argument is @var{lib}; the three names are
-@file{@var{lib}.elc}, @file{@var{lib}.el}, and lastly just
-@file{@var{lib}}. If @file{@var{lib}.elc} exists, it is by convention
-the result of compiling @file{@var{lib}.el}; it is better to load the
-compiled file, since it will load and run faster.
-
- If @code{load-library} finds that @file{@var{lib}.el} is newer than
-@file{@var{lib}.elc} file, it issues a warning, because it's likely
-that somebody made changes to the @file{.el} file and forgot to
-recompile it. Nonetheless, it loads @file{@var{lib}.elc}. This is
-because people often leave unfinished edits the source file, and don't
-recompile it until they think it is ready to use.
+@cindex load path for Emacs Lisp
+ If an Emacs Lisp file is installed in the Emacs Lisp @dfn{load path}
+(defined below), you can load it by typing @kbd{M-x load-library},
+instead of using @kbd{M-x load-file}. The @kbd{M-x load-library}
+command prompts for a @dfn{library name} rather than a file name; it
+searches through each directory in the Emacs Lisp load path, trying to
+find a file matching that library name. If the library name is
+@samp{@var{foo}}, it tries looking for files named
+@file{@var{foo}.elc}, @file{@var{foo}.el}, and lastly just
+@file{@var{foo}}; the first one found is loaded. This command prefers
+@file{.elc} files over @file{.el} files because compiled files load
+and run faster. If it finds that @file{@var{lib}.el} is newer than
+@file{@var{lib}.elc}, it issues a warning, in case someone made
+changes to the @file{.el} file and forgot to recompile it, but loads
+the @file{.elc} file anyway. (Due to this behavior, you can save
+unfinished edits to Emacs Lisp source files, and not recompile until
+your changes are ready for use.)
+
+ Emacs Lisp programs usually load Emacs Lisp files using the
+@code{load} function. This is similar to @code{load-library}, but is
+lower-level and accepts additional arguments. @xref{How Programs Do
+Loading,,, elisp, the Emacs Lisp Reference Manual}.
@vindex load-path
- The variable @code{load-path} specifies the sequence of directories
-searched by @kbd{M-x load-library}. Its value should be a list of
-strings that are directory names; in addition, @code{nil} in this list
-stands for the current default directory. (Generally, it is not a
-good idea to put @code{nil} in the list; if you find yourself wishing
+ The Emacs Lisp load path is specified by the variable
+@code{load-path}. Its value should be a list of directory names
+(strings). These directories are searched, in the specified order, by
+the @kbd{M-x load-library} command, the lower-level @code{load}
+function, and other Emacs functions that find Emacs Lisp libraries. A
+list entry in @code{load-path} can also have the special value
+@code{nil}, which stands for the current default directory, but it is
+almost always a bad idea to use this. (If you find yourself wishing
that @code{nil} were in the list, most likely what you really want is
-to do @kbd{M-x load-file} this once.)
+to use @kbd{M-x load-file}.)
The default value of @code{load-path} is a list of directories where
the Lisp code for Emacs itself is stored. If you have libraries of
-your own, put them in a single directory and add that directory to
-@code{load-path}, by adding a line like this to your init file
-(@pxref{Init File}):
+your own in another directory, you can add that directory to the load
+path. Unlike most other variables described in this manual,
+@code{load-path} cannot be changed via the Customize interface
+(@pxref{Easy Customization}), but you can add a directory to it by
+putting a line like this in your init file (@pxref{Init File}):
@example
-(add-to-list 'load-path "/path/to/lisp/libraries")
+(add-to-list 'load-path "/path/to/my/lisp/library")
@end example
@cindex autoload
- Some commands are @dfn{autoloaded}: when you run them, Emacs will
-automatically load the associated library first. For instance, the
-@code{compile} and @code{compilation-mode} commands
-(@pxref{Compilation}) are autoloaded; if you call either command,
-Emacs automatically loads the @code{compile} library. In contrast,
-the command @code{recompile} is not autoloaded, so it is unavailable
-until you load the @code{compile} library.
+ Some commands are @dfn{autoloaded}; when you run them, Emacs
+automatically loads the associated library first. For instance, the
+@kbd{M-x compile} command (@pxref{Compilation}) is autoloaded; if you
+call it, Emacs automatically loads the @code{compile} library first.
+In contrast, the command @kbd{M-x recompile} is not autoloaded, so it
+is unavailable until you load the @code{compile} library.
+
+@vindex help-enable-auto-load
+ Automatic loading can also occur when you look up the documentation
+of an autoloaded command (@pxref{Name Help}), if the documentation
+refers to other functions and variables in its library (loading the
+library lets Emacs properly set up the hyperlinks in the @file{*Help*}
+buffer). To disable this feature, change the variable
+@code{help-enable-auto-load} to @code{nil}.
@vindex load-dangerous-libraries
@cindex Lisp files byte-compiled by XEmacs
@node Lisp Eval
@section Evaluating Emacs Lisp Expressions
-@cindex Emacs-Lisp mode
-@cindex mode, Emacs-Lisp
+@cindex Emacs Lisp mode
+@cindex mode, Emacs Lisp
+@cindex evaluation, Emacs Lisp
@findex emacs-lisp-mode
- Lisp programs intended to be run in Emacs should be edited in
-Emacs-Lisp mode; this happens automatically for file names ending in
-@file{.el}. By contrast, Lisp mode itself is used for editing Lisp
-programs intended for other Lisp systems. To switch to Emacs-Lisp mode
-explicitly, use the command @kbd{M-x emacs-lisp-mode}.
-
- For testing of Lisp programs to run in Emacs, it is often useful to
-evaluate part of the program as it is found in the Emacs buffer. For
-example, after changing the text of a Lisp function definition,
-evaluating the definition installs the change for future calls to the
-function. Evaluation of Lisp expressions is also useful in any kind of
-editing, for invoking noninteractive functions (functions that are
-not commands).
+ Emacs Lisp mode is the major mode for editing Emacs Lisp. Its mode
+command is @kbd{M-x emacs-lisp-mode}.
-@table @kbd
-@item M-:
-Read a single Lisp expression in the minibuffer, evaluate it, and print
-the value in the echo area (@code{eval-expression}).
-@item C-x C-e
-Evaluate the Lisp expression before point, and print the value in the
-echo area (@code{eval-last-sexp}).
-@item C-M-x
+ Emacs provides several commands for evaluating Emacs Lisp
+expressions. You can use these commands in Emacs Lisp mode, to test
+your Emacs Lisp code as it is being written. For example, after
+re-writing a function, you can evaluate the function definition to
+make it take effect for subsequent function calls. These commands are
+also available globally, and can be used outside Emacs Lisp mode.
+
+@table @asis
+@item @kbd{M-:}
+Read a single Emacs Lisp expression in the minibuffer, evaluate it,
+and print the value in the echo area (@code{eval-expression}).
+@item @kbd{C-x C-e}
+Evaluate the Emacs Lisp expression before point, and print the value
+in the echo area (@code{eval-last-sexp}).
+@item @kbd{C-M-x} @r{(in Emacs Lisp mode)}
+@itemx @kbd{M-x eval-defun}
Evaluate the defun containing or after point, and print the value in
the echo area (@code{eval-defun}).
-@item M-x eval-region
-Evaluate all the Lisp expressions in the region.
-@item M-x eval-buffer
-Evaluate all the Lisp expressions in the buffer.
+@item @kbd{M-x eval-region}
+Evaluate all the Emacs Lisp expressions in the region.
+@item @kbd{M-x eval-buffer}
+Evaluate all the Emacs Lisp expressions in the buffer.
@end table
@ifinfo
@kindex M-:
@end ifnotinfo
@findex eval-expression
- @kbd{M-:} (@code{eval-expression}) is the most basic command for evaluating
-a Lisp expression interactively. It reads the expression using the
-minibuffer, so you can execute any expression on a buffer regardless of
-what the buffer contains. When the expression is evaluated, the current
-buffer is once again the buffer that was current when @kbd{M-:} was
-typed.
-
-@kindex C-M-x @r{(Emacs-Lisp mode)}
-@findex eval-defun
- In Emacs-Lisp mode, the key @kbd{C-M-x} is bound to the command
-@code{eval-defun}, which parses the defun containing or following point
-as a Lisp expression and evaluates it. The value is printed in the echo
-area. This command is convenient for installing in the Lisp environment
-changes that you have just made in the text of a function definition.
-
- @kbd{C-M-x} treats @code{defvar} expressions specially. Normally,
-evaluating a @code{defvar} expression does nothing if the variable it
-defines already has a value. But @kbd{C-M-x} unconditionally resets the
-variable to the initial value specified in the @code{defvar} expression.
-@code{defcustom} expressions are treated similarly.
-This special feature is convenient for debugging Lisp programs.
-Typing @kbd{C-M-x} on a @code{defface} expression reinitializes
-the face according to the @code{defface} specification.
+ @kbd{M-:} (@code{eval-expression}) reads an expression using the
+minibuffer, and evaluates it. (Before evaluating the expression, the
+current buffer switches back to the buffer that was current when you
+typed @kbd{M-:}, not the minibuffer into which you typed the
+expression.)
@kindex C-x C-e
@findex eval-last-sexp
- The command @kbd{C-x C-e} (@code{eval-last-sexp}) evaluates the Lisp
-expression preceding point in the buffer, and displays the value in the
-echo area. It is available in all major modes, not just Emacs-Lisp
-mode. It does not treat @code{defvar} specially.
-
- When the result of an evaluation is an integer, you can type
-@kbd{C-x C-e} a second time to display the value of the integer result
-in additional formats (octal, hexadecimal, and character).
-
- If @kbd{C-x C-e}, or @kbd{M-:} is given a numeric argument, it
-inserts the value into the current buffer at point, rather than
-displaying it in the echo area. The argument's value does not matter.
-@kbd{C-M-x} with a numeric argument instruments the function
-definition for Edebug (@pxref{Instrumenting, Instrumenting for Edebug,, elisp, the Emacs Lisp Reference Manual}).
+ The command @kbd{C-x C-e} (@code{eval-last-sexp}) evaluates the
+Emacs Lisp expression preceding point in the buffer, and displays the
+value in the echo area. When the result of an evaluation is an
+integer, you can type @kbd{C-x C-e} a second time to display the value
+of the integer result in additional formats (octal, hexadecimal, and
+character).
+
+ If @kbd{M-:} or @kbd{C-x C-e} is given a prefix argument, it inserts
+the value into the current buffer at point, rather than displaying it
+in the echo area. The argument's value does not matter.
+
+@kindex C-M-x @r{(Emacs Lisp mode)}
+@findex eval-defun
+ The @code{eval-defun} command is bound to @kbd{C-M-x} in Emacs Lisp
+mode. It evaluates the top-level Lisp expression containing or
+following point, and prints the value in the echo area. In this
+context, a top-level expression is referred to as a ``defun'', but it
+need not be an actual @code{defun} (function definition). In
+particular, this command treats @code{defvar} expressions specially.
+Normally, evaluating a @code{defvar} expression does nothing if the
+variable it defines already has a value. But this command
+unconditionally resets the variable to the initial value specified by
+the @code{defvar}; this is convenient for debugging Emacs Lisp
+programs. @code{defcustom} and @code{defface} expressions are treated
+similarly. Note that the other commands documented in this section do
+not have this special feature.
+
+ With a prefix argument, @kbd{C-M-x} instruments the function
+definition for Edebug, the Emacs Lisp Debugger. @xref{Instrumenting,
+Instrumenting for Edebug,, elisp, the Emacs Lisp Reference Manual}.
@findex eval-region
@findex eval-buffer
- The most general command for evaluating Lisp expressions from a buffer
-is @code{eval-region}. @kbd{M-x eval-region} parses the text of the
-region as one or more Lisp expressions, evaluating them one by one.
-@kbd{M-x eval-buffer} is similar but evaluates the entire
-buffer. This is a reasonable way to install the contents of a file of
-Lisp code that you are ready to test. Later, as you find bugs and
-change individual functions, use @kbd{C-M-x} on each function that you
-change. This keeps the Lisp world in step with the source file.
+ The command @kbd{M-x eval-region} parses the text of the region as
+one or more Lisp expressions, evaluating them one by one. @kbd{M-x
+eval-buffer} is similar but evaluates the entire buffer.
@vindex eval-expression-print-level
@vindex eval-expression-print-length
@vindex eval-expression-debug-on-error
- The two customizable variables @code{eval-expression-print-level} and
-@code{eval-expression-print-length} control the maximum depth and length
-of lists to print in the result of the evaluation commands before
-abbreviating them. @code{eval-expression-debug-on-error} controls
-whether evaluation errors invoke the debugger when these commands are
-used; its default is @code{t}.
+ The options @code{eval-expression-print-level} and
+@code{eval-expression-print-length} control the maximum depth and
+length of lists to print in the result of the evaluation commands
+before abbreviating them. @code{eval-expression-debug-on-error}
+controls whether evaluation errors invoke the debugger when these
+commands are used; its default is @code{t}.
@node Lisp Interaction
@section Lisp Interaction Buffers
- When Emacs starts up, it contains a buffer named @samp{*scratch*},
-which is provided for evaluating Lisp expressions interactively inside
-Emacs. Its major mode is Lisp Interaction mode.
+@findex lisp-interaction-mode
+ When Emacs starts up, it contains a buffer named @file{*scratch*},
+which is provided for evaluating Emacs Lisp expressions interactively.
+Its major mode is Lisp Interaction mode. You can also enable Lisp
+Interaction mode by typing @kbd{M-x lisp-interaction-mode}.
@findex eval-print-last-sexp
@kindex C-j @r{(Lisp Interaction mode)}
- The simplest way to use the @samp{*scratch*} buffer is to insert
-Lisp expressions and type @kbd{C-j} (@code{eval-print-last-sexp})
-after each expression. This command reads the Lisp expression before
-point, evaluates it, and inserts the value in printed representation
-before point. The result is a complete typescript of the expressions
-you have evaluated and their values.
+ In the @file{*scratch*} buffer, and other Lisp Interaction mode
+buffers, @kbd{C-j} (@code{eval-print-last-sexp}) evaluates the Lisp
+expression before point, and inserts the value at point. Thus, as you
+type expressions into the buffer followed by @kbd{C-j} after each
+expression, the buffer records a transcript of the evaluated
+expressions and their values. All other commands in Lisp Interaction
+mode are the same as in Emacs Lisp mode.
@vindex initial-scratch-message
- At startup, the @samp{*scratch*} buffer contains a short message, in
+ At startup, the @file{*scratch*} buffer contains a short message, in
the form of a Lisp comment, that explains what it is for. This
message is controlled by the variable @code{initial-scratch-message},
-which should be either a string or @code{nil}. If you set it to the
-empty string, or @code{nil}, the initial message is suppressed.
-
-@findex lisp-interaction-mode
- All other commands in Lisp Interaction mode are the same as in Emacs
-Lisp mode. You can enable Lisp Interaction mode by typing @kbd{M-x
-lisp-interaction-mode}.
+which should be either a string, or @code{nil} (which means to
+suppress the message).
@findex ielm
- An alternative way of evaluating Emacs Lisp expressions interactively
-is to use Inferior Emacs-Lisp mode, which provides an interface rather
-like Shell mode (@pxref{Shell Mode}) for evaluating Emacs Lisp
-expressions. Type @kbd{M-x ielm} to create an @samp{*ielm*} buffer
-which uses this mode. For more information see that command's
-documentation.
+ An alternative way of evaluating Emacs Lisp expressions
+interactively is to use Inferior Emacs Lisp mode, which provides an
+interface rather like Shell mode (@pxref{Shell Mode}) for evaluating
+Emacs Lisp expressions. Type @kbd{M-x ielm} to create an
+@file{*ielm*} buffer which uses this mode. For more information, see
+that command's documentation.
@node External Lisp
@section Running an External Lisp
+@cindex Lisp mode
+@cindex mode, Lisp
+@cindex Common Lisp
- Emacs has facilities for running programs in other Lisp systems. You can
-run a Lisp process as an inferior of Emacs, and pass expressions to it to
-be evaluated. You can also pass changed function definitions directly from
-the Emacs buffers in which you edit the Lisp programs to the inferior Lisp
-process.
+ Lisp mode is the major mode for editing programs written in
+general-purpose Lisp dialects, such as Common Lisp. Its mode command
+is @kbd{M-x lisp-mode}. Emacs uses Lisp mode automatically for files
+whose names end in @file{.l}, @file{.lsp}, or @file{.lisp}.
@findex run-lisp
@vindex inferior-lisp-program
@kindex C-x C-z
- To run an inferior Lisp process, type @kbd{M-x run-lisp}. This runs
-the program named @code{lisp}, the same program you would run by typing
-@code{lisp} as a shell command, with both input and output going through
-an Emacs buffer named @samp{*lisp*}. That is to say, any ``terminal
-output'' from Lisp will go into the buffer, advancing point, and any
-``terminal input'' for Lisp comes from text in the buffer. (You can
-change the name of the Lisp executable file by setting the variable
-@code{inferior-lisp-program}.)
-
- To give input to Lisp, go to the end of the buffer and type the input,
-terminated by @key{RET}. The @samp{*lisp*} buffer is in Inferior Lisp
-mode, which combines the special characteristics of Lisp mode with most
-of the features of Shell mode (@pxref{Shell Mode}). The definition of
-@key{RET} to send a line to a subprocess is one of the features of Shell
-mode.
-
-@findex lisp-mode
- For the source files of programs to run in external Lisps, use Lisp
-mode. You can switch to this mode with @kbd{M-x lisp-mode}, and it is
-used automatically for files whose names end in @file{.l},
-@file{.lsp}, or @file{.lisp}.
+ You can run an external Lisp session as a subprocess or
+@dfn{inferior process} of Emacs, and pass expressions to it to be
+evaluated. To begin an external Lisp session, type @kbd{M-x
+run-lisp}. This runs the program named @command{lisp}, and sets it up
+so that both input and output go through an Emacs buffer named
+@file{*inferior-lisp*}. To change the name of the Lisp program run by
+@kbd{M-x run-lisp}, change the variable @code{inferior-lisp-program}.
+
+ The major mode for the @file{*lisp*} buffer is Inferior Lisp mode,
+which combines the characteristics of Lisp mode and Shell mode
+(@pxref{Shell Mode}). To send input to the Lisp session, go to the
+end of the @file{*lisp*} buffer and type the input, followed by
+@key{RET}. Terminal output from the Lisp session is automatically
+inserted in the buffer.
@kindex C-M-x @r{(Lisp mode)}
@findex lisp-eval-defun
- When you edit a function in a Lisp program you are running, the easiest
-way to send the changed definition to the inferior Lisp process is the key
-@kbd{C-M-x}. In Lisp mode, this runs the function @code{lisp-eval-defun},
-which finds the defun around or following point and sends it as input to
-the Lisp process. (Emacs can send input to any inferior process regardless
-of what buffer is current.)
-
- Contrast the meanings of @kbd{C-M-x} in Lisp mode (for editing
-programs to be run in another Lisp system) and Emacs-Lisp mode (for
-editing Lisp programs to be run in Emacs; see @pxref{Lisp Eval}): in
-both modes it has the effect of installing the function definition
-that point is in, but the way of doing so is different according to
-where the relevant Lisp environment is found.
+ When you edit a Lisp program in Lisp mode, you can type @kbd{C-M-x}
+(@code{lisp-eval-defun}) to send an expression from the Lisp mode
+buffer to a Lisp session that you had started with @kbd{M-x run-lisp}.
+The expression sent is the top-level Lisp expression at or following
+point. The resulting value goes as usual into the
+@file{*inferior-lisp*} buffer. Note that the effect of @kbd{C-M-x} in
+Lisp mode is thus very similar to its effect in Emacs Lisp mode
+(@pxref{Lisp Eval}), except that the expression is sent to a different
+Lisp environment instead of being evaluated in Emacs.
+
+@findex scheme-mode
+@findex run-scheme
+@cindex Scheme mode
+@cindex mode, Scheme
+@kindex C-M-x @r{(Scheme mode)}
+ The facilities for editing Scheme code, and for sending expressions
+to a Scheme subprocess, are very similar. Scheme source files are
+edited in Scheme mode, which can be explicitly enabled with @kbd{M-x
+scheme-mode}. You can initiate a Scheme session by typing @kbd{M-x
+run-scheme} (the buffer for interacting with Scheme is named
+@file{*scheme*}), and send expressions to it by typing @kbd{C-M-x}.