This is Info file ../info/emacs, produced by Makeinfo-1.54 from the
input file emacs.texi.
File: emacs,  Node: ForIndent Num,  Next: ForIndent Conv,  Prev: ForIndent Cont,  Up: Fortran Indent
Line Numbers
............
   If a number is the first non-whitespace in the line, Fortran
indentation assumes it is a line number and moves it to columns 0
through 4.  (Columns always count from 0 in GNU Emacs.)
   Line numbers of four digits or less are normally indented one space.
The variable `fortran-line-number-indent' controls this; it specifies
the maximum indentation a line number can have.  Line numbers are
indented to right-justify them to end in column 4 unless that would
require more than this maximum indentation.  The default value of the
variable is 1.
   Simply inserting a line number is enough to indent it according to
these rules.  As each digit is inserted, the indentation is recomputed.
To turn off this feature, set the variable
`fortran-electric-line-number' to `nil'.  Then inserting line numbers
is like inserting anything else.
File: emacs,  Node: ForIndent Conv,  Next: ForIndent Vars,  Prev: ForIndent Num,  Up: Fortran Indent
Syntactic Conventions
.....................
   Fortran mode assumes that you follow certain conventions that
simplify the task of understanding a Fortran program well enough to
indent it properly:
   * Two nested `do' loops never share a `continue' statement.
   * Fortran keywords such as `if', `else', `then', `do' and others are
     written without embedded whitespace or line breaks.
     Fortran compilers generally ignore whitespace outside of string
     constants, but Fortran mode does not recognize these keywords if
     they are not contiguous.  Constructs such as `else if' or `end do'
     are acceptable, but the second word should be on the same line as
     the first and not on a continuation line.
If you fail to follow these conventions, the indentation commands may
indent some lines unaesthetically.  However, a correct Fortran program
retains its meaning when reindented even if the conventions are not
followed.
File: emacs,  Node: ForIndent Vars,  Prev: ForIndent Conv,  Up: Fortran Indent
Variables for Fortran Indentation
.................................
   Several additional variables control how Fortran indentation works:
`fortran-do-indent'
     Extra indentation within each level of `do' statement (default 3).
`fortran-if-indent'
     Extra indentation within each level of `if' statement (default 3).
     This value is also used for extra indentation within each level of
     the Fortran 90 `where' statement.
`fortran-structure-indent'
     Extra indentation within each level of `structure', `union', or
     `map' statements (default 3).
`fortran-continuation-indent'
     Extra indentation for bodies of continuation lines (default 5).
`fortran-check-all-num-for-matching-do'
     If this is `nil', indentation assumes that each `do' statement
     ends on a `continue' statement.  Therefore, when computing
     indentation for a statement other than `continue', it can save time
     by not checking for a `do' statement ending there.  If this is
     non-`nil', indenting any numbered statement must check for a `do'
     that ends there.  The default is `nil'.
`fortran-blink-matching-if'
     If this is `t', indenting an `endif' statement moves the cursor
     momentarily to the matching `if' statement to show where it is.
     The default is `nil'.
`fortran-minimum-statement-indent-fixed'
     Minimum indentation for fortran statements when using fixed format
     continuation line style.  Statement bodies are never indented less
     than this much.  The default is 6.
`fortran-minimum-statement-indent-tab'
     Minimum indentation for fortran statements for tab format
     continuation line style.  Statement bodies are never indented less
     than this much.  The default is 8.
File: emacs,  Node: Fortran Comments,  Next: Fortran Autofill,  Prev: Fortran Indent,  Up: Fortran
Comments
--------
   The usual Emacs comment commands assume that a comment can follow a
line of code.  In Fortran, the standard comment syntax requires an
entire line to be just a comment.  Therefore, Fortran mode replaces the
standard Emacs comment commands and defines some new variables.
   Fortran mode can also handle a nonstandard comment syntax where
comments start with `!' and can follow other text.  Because only some
Fortran compilers accept this syntax, Fortran mode will not insert such
comments unless you have said in advance to do so.  To do this, set the
variable `comment-start' to `"!"' (*note Variables::.).
`M-;'
     Align comment or insert new comment (`fortran-comment-indent').
`C-x ;'
     Applies to nonstandard `!' comments only.
`C-c ;'
     Turn all lines of the region into comments, or (with argument)
     turn them back into real code (`fortran-comment-region').
   `M-;' in Fortran mode is redefined as the command
`fortran-comment-indent'.  Like the usual `M-;' command, this
recognizes any kind of existing comment and aligns its text
appropriately; if there is no existing comment, a comment is inserted
and aligned.  But inserting and aligning comments are not the same in
Fortran mode as in other modes.
   When a new comment must be inserted, if the current line is blank, a
full-line comment is inserted.  On a non-blank line, a nonstandard `!'
comment is inserted if you have said you want to use them.  Otherwise a
full-line comment is inserted on a new line before the current line.
   Nonstandard `!' comments are aligned like comments in other
languages, but full-line comments are different.  In a standard
full-line comment, the comment delimiter itself must always appear in
column zero.  What can be aligned is the text within the comment.  You
can choose from three styles of alignment by setting the variable
`fortran-comment-indent-style' to one of these values:
`fixed'
     Align the text at a fixed column, which is the sum of
     `fortran-comment-line-extra-indent' and the minimum statement
     indentation.  This is the default.
     The minimum statement indentation is
     `fortran-minimum-statement-indent-fixed' for fixed format
     continuation line style and `fortran-minimum-statement-indent-tab'
     for tab format style.
`relative'
     Align the text as if it were a line of code, but with an additional
     `fortran-comment-line-extra-indent' columns of indentation.
`nil'
     Don't move text in full-line columns automatically at all.
   In addition, you can specify the character to be used to indent
within full-line comments by setting the variable
`fortran-comment-indent-char' to the single-character string you want
to use.
   Fortran mode introduces two variables `comment-line-start' and
`comment-line-start-skip' which play for full-line comments the same
roles played by `comment-start' and `comment-start-skip' for ordinary
text-following comments.  Normally these are set properly by Fortran
mode so you do not need to change them.
   The normal Emacs comment command `C-x ;' has not been redefined.  If
you use `!' comments, this command can be used with them.  Otherwise it
is useless in Fortran mode.
   The command `C-c ;' (`fortran-comment-region') turns all the lines
of the region into comments by inserting the string `C$$$' at the front
of each one.  With a numeric argument, it turns the region back into
live code by deleting `C$$$' from the front of each line in it.  The
string used for these comments can be controlled by setting the
variable `fortran-comment-region'.  Note that here we have an example
of a command and a variable with the same name; these two uses of the
name never conflict because in Lisp and in Emacs it is always clear
from the context which one is meant.
File: emacs,  Node: Fortran Autofill,  Next: Fortran Columns,  Prev: Fortran Comments,  Up: Fortran
Fortran Auto Fill Mode
----------------------
   Fortran Auto Fill mode is a minor mode which automatically splits
Fortran statements as you insert them when they become too wide.
Splitting a statement involves making continuation lines.  This
splitting happens when you type SPC, RET, or TAB, and also in the
Fortran indentation commands.
   `M-x fortran-auto-fill-mode' turns Fortran Auto Fill mode on if it
was off, or off if it was on.  This command works the same as `M-x
auto-fill-mode' does for normal Auto Fill mode (*note Filling::.).  A
positive numeric argument turns Fortran Auto Fill mode on, and a
negative argument turns it off.  You can see when Fortran Auto Fill mode
is in effect by the presence of the word `Fill' in the mode line,
inside the parentheses.  Fortran Auto Fill mode is a minor mode, turned
on or off for each buffer individually.  *Note Minor Modes::.
   Fortran Auto Fill mode breaks lines at spaces or delimiters when the
lines get longer than the desired width (the value of `fill-column').
The delimiters that Fortran Auto Fill mode may break at are `,', `'',
`+', `-', `/', `*', `=', and `)'.  The line break comes after the
delimiter if the variable `fortran-break-before-delimiters' is `nil'.
Otherwise (and by default), the break comes before the delimiter.
   By default, Fortran Auto Fill mode is not enabled.  If you want this
feature turned on permanently, add a hook function to
`fortran-mode-hook' to execute `(fortran-auto-fill-mode 1)'.  *Note
Hooks::.
File: emacs,  Node: Fortran Columns,  Next: Fortran Abbrev,  Prev: Fortran Autofill,  Up: Fortran
Columns
-------
`C-c C-r'
     Display a "column ruler" momentarily above the current line
     (`fortran-column-ruler').
`C-c C-w'
     Split the current window horizontally temporarily so that it is 72
     columns wide.  This may help you avoid making lines longer than
     the 72 character limit that some fortran compilers impose
     (`fortran-window-create-momentarily').
   The command `C-c C-r' (`fortran-column-ruler') shows a column ruler
momentarily above the current line.  The comment ruler is two lines of
text that show you the locations of columns with special significance in
Fortran programs.  Square brackets show the limits of the columns for
line numbers, and curly brackets show the limits of the columns for the
statement body.  Column numbers appear above them.
   Note that the column numbers count from zero, as always in GNU Emacs.
As a result, the numbers may be one less than those you are familiar
with; but the positions they indicate in the line are standard for
Fortran.
   The text used to display the column ruler is the value of the
variable `fortran-comment-ruler'.  By changing this variable, you can
change the display.
   For even more help, use `C-c C-w' (`fortran-window-create'), a
command which splits the current window horizontally, making a window 72
columns wide.  By editing in this window you can immediately see when
you make a line too wide to be correct Fortran.
File: emacs,  Node: Fortran Abbrev,  Prev: Fortran Columns,  Up: Fortran
Fortran Keyword Abbrevs
-----------------------
   Fortran mode provides many built-in abbrevs for common keywords and
declarations.  These are the same sort of abbrev that you can define
yourself.  To use them, you must turn on Abbrev mode.  *Note Abbrevs::.
   The built-in abbrevs are unusual in one way: they all start with a
semicolon.  You cannot normally use semicolon in an abbrev, but Fortran
mode makes this possible by changing the syntax of semicolon to "word
constituent."
   For example, one built-in Fortran abbrev is `;c' for `continue'.  If
you insert `;c' and then insert a punctuation character such as a space
or a newline, the `;c' expands automatically to `continue', provided
Abbrev mode is enabled.
   Type `;?' or `;C-h' to display a list of all the built-in Fortran
abbrevs and what they stand for.
File: emacs,  Node: Asm Mode,  Prev: Fortran,  Up: Programs
Asm Mode
========
   Asm mode is a major mode for editing files of assembler code.  It
defines these commands:
`TAB'
     `tab-to-tab-stop'.
`LFD'
     Insert a newline and then indent using `tab-to-tab-stop'.
     Insert a colon and then remove the indentation from before the
     label preceding colon.  Then do `tab-to-tab-stop'.
     Insert or align a comment.
   The variable `asm-comment-char' specifies which character starts
comments in assembler syntax.
File: emacs,  Node: Building,  Next: Abbrevs,  Prev: Programs,  Up: Top
Compiling and Testing Programs
******************************
   The previous chapter discusses the Emacs commands that are useful for
making changes in programs.  This chapter deals with commands that
assist in the larger process of developing and maintaining programs.
* Menu:
* Compilation::                   Compiling programs in languages other
                                    than Lisp (C, Pascal, etc.)
* Debuggers::	                  Running symbolic debuggers for
                                    non-Lisp programs.
* 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.
* Interaction: Lisp Interaction.  Executing Lisp in an Emacs buffer.
* Eval: Lisp Eval.                Executing a single Lisp expression in Emacs.
* External Lisp::                 Communicating through Emacs with a
                                    separate Lisp.
File: emacs,  Node: Compilation,  Next: Debuggers,  Up: Building
Running `make', or Compilers Generally
======================================
   Emacs can run compilers for noninteractive languages such as C and
Fortran as inferior processes, feeding the error log into an Emacs
buffer.  It can also parse the error messages and show you the source
lines where compilation errors occurred.
`M-x compile'
     Run a compiler asynchronously under Emacs, with error messages to
     `*compilation*' buffer.
`M-x grep'
     Run `grep' asynchronously under Emacs, with matching lines listed
     in the buffer named `*grep*'.
`M-x kill-compilation'
`M-x kill-grep'
     Kill the running compilation or `grep' subprocess.
`C-x `'
     Visit the locus of the next compiler error message or `grep' match.
   To run `make' or another compilation command, do `M-x compile'.
This command reads a shell command line using the minibuffer, and then
executes the command in an inferior shell, putting output in the buffer
named `*compilation*'.  The current buffer's default directory is used
as the working directory for the execution of the command; normally,
therefore, the compilation happens in this directory.
   When the shell command line is read, the minibuffer appears
containing a default command line, which is the command you used the
last time you did `M-x compile'.  If you type just RET, the same command
line is used again.  For the first `M-x compile', the default is `make
   The default compilation command comes from the variable
`compile-command'; if the appropriate compilation command for a file is
something other than `make -k', it can be useful for the file to
specify a local value for `compile-command' (*note File Variables::.).
   Starting a compilation displays the buffer `*compilation*' in
another window but does not select it.  The buffer's mode line tells you
whether compilation is finished, with the word `run' or `exit' inside
the parentheses.  You do not have to keep this buffer visible;
compilation continues in any case.  While a compilation is going on, the
string `Compiling' appears in the mode lines of all windows.  When this
string disappears, the compilation is finished.
   To kill the compilation process, do `M-x kill-compilation'.  When
the compiler process terminates, the mode line of the `*compilation*'
buffer changes to say `signal' instead of `run'.  Starting a new
compilation also kills any running compilation, as only one can exist
at any time.  However, `M-x compile' asks for confirmation before
actually killing a compilation that is running.
   The `*compilation*' buffer uses a special major mode, Compilation
mode.  This mode provides the keys SPC and DEL to scroll by screenfuls,
and `M-n' and `M-p' to move to the next or previous error message.  You
can also use `M-{' and `M-}' to move up or down to an error message for
a different source file.  You can visit the source for any particular
error message by moving point in `*compilation*' to that error message
and typing `C-c C-c' (`compile-goto-error').
   To parse the compiler error messages sequentially, type `C-x `'
(`next-error').  The character following the `C-x' is the backquote or
"grave accent," not the single-quote.  This command is available in all
buffers, not just in `*compilation*'.  It displays the next error
message at the top of one window and source location of the error in
another window.
   The first time `C-x `' is used after the start of a compilation, it
moves to the first error's location.  Subsequent uses of `C-x `'
advance down the data set up by the first use.  When the preparsed error
messages are exhausted, the next `C-x `' checks for any more error
messages that have come in; this is useful if you start editing the
compilation errors while the compilation is still going on.  If no more
error messages have come in, `C-x `' reports an error.
   `C-u C-x `' discards the preparsed error message data and parses the
`*compilation*' buffer over again, then displaying the first error.
This way, you can process the same set of errors again.
   Instead of running a compiler, you can run `grep' and see the lines
on which matches were found.  To do this, type `M-x grep' with an
argument line that contains the same arguments you would give `grep'
when running it normally: a `grep'-style regexp (usually in
single-quotes to quote the shell's special characters) followed by file
names which may use wildcards.  The output from `grep' goes in the
`*grep*' buffer and the lines that matched can be found with `C-x `' as
if they were compilation errors.
   Note: a shell is used to run the compile command, but the shell is
told that it should be noninteractive.  This means in particular that
the shell starts up with no prompt.  If you find your usual shell
prompt making an unsightly appearance in the `*compilation*' buffer, it
means you have made a mistake in your shell's init file (`.cshrc' or
`.shrc' or ...) by setting the prompt unconditionally.  The shell init
file should set the prompt only if there already is a prompt.  In
`csh', here is how to do it:
     if ($?prompt) set prompt = ...
File: emacs,  Node: Debuggers,  Next: Executing Lisp,  Prev: Compilation,  Up: Building
Running Debuggers Under Emacs
=============================
   The GUD (Grand Unified Debugger) library provides an interface to
various symbolic debuggers from within Emacs.  We recommend the
debugger GDB, which is free software, but you can also run DBX or SDB
if you have them.
* Menu:
* Starting GUD::	How to start a debugger subprocess.
* Debugger Operation::	Connection between the debugger and source buffers.
* Commands of GUD::	Keybindings for common commands.
* GUD Customization::	Defining your own commands for GUD.
File: emacs,  Node: Starting GUD,  Next: Debugger Operation,  Up: Debuggers
Starting GUD
------------
   There are three commands for starting a debugger, each corresponding
to a particular debugger program.
`M-x gdb RET FILE RET'
     Run GDB as a subprocess of Emacs.  This command creates a buffer
     for input and output to GDB, and switches to it.  If a GDB buffer
     already exists, it just switches to that buffer.
`M-x dbx RET FILE RET'
     Similar, but run DBX instead of GDB.
`M-x sdb RET FILE RET'
     Similar, but run SDB instead of GDB.
     Some versions of SDB do not mention source file names in their
     messages.  When you use them, you need to have a valid tags table
     (*note Tags::.) in order for GUD to find functions in the source
     code.  If you have not visited a tags table or the tags table
     doesn't list one of the functions, you get a message saying `The
     sdb support requires a valid tags table to work'.  If this
     happens, generate a valid tags table in the working directory and
     try again.
`M-x xdb'
     Similar, but run XDB instead of GDB.
   You can only run one debugger process at a time.
   Each of these commands takes one argument: a command line to invoke
the debugger.  In the simplest case, specify just the name of the
executable file you want to debug.  You may also use options that the
debugger supports.  However, shell wild cards and variables are not
allowed.  GUD assumes that the first argument not preceded by a `-' is
the executable file name.
File: emacs,  Node: Debugger Operation,  Next: Commands of GUD,  Prev: Starting GUD,  Up: Debuggers
Debugger Operation
------------------
   When you run a debugger with GUD, the debugger uses an Emacs buffer
for its ordinary input and output.  This is called the GUD buffer.  The
debugger uses other Emacs buffers to display the source files of the
program.  An arrow (`=>') in one of these buffers indicates the current
execution line.  Moving point in this buffer does not move the arrow.
   You can start editing these source files at any time in the buffers
that were made to display them.  The arrow is not part of the file's
text; it appears only on the screen.  If you do modify a source file,
keep in mind that inserting or deleting lines will throw off the arrow's
positioning; GUD has no way of figuring out which line corresponded
before your changes to the line number in a debugger message.  Also,
you'll typically have to recompile and restart the program for your
changes to be reflected in the debugger's tables.
   If you wish, you can control your debugger process entirely through
the debugger buffer, which uses a variant of Shell mode.  All the usual
commands for your debugger are available, and you can use the Shell mode
history commands to repeat them.
File: emacs,  Node: Commands of GUD,  Next: GUD Customization,  Prev: Debugger Operation,  Up: Debuggers
Commands of GUD
---------------
   GUD provides a command available in all buffers for setting
breakpoints.  This command is defined globally because you need to use
it in the source files' buffers.
`C-x SPC'
     Set a breakpoint on the line that point is on.
   Here are the other commands provided by GUD.  The keys starting with
`C-c' are available only in the GUD interaction buffer.  The bindings
that start with `C-x C-a' are available in the GUD buffer and also in
source files.
`C-c C-l'
`C-x C-a C-l'
     Display in another window the last line referred to in the GUD
     buffer (that is, the line indicated in the last location message).
     This runs the command `gud-refresh'.
`C-c C-s'
`C-x C-a C-s'
     Execute a single line of code (`gud-step').  If the code contains
     a function call, execution stops after entering the called
     function.
`C-c C-n'
`C-x C-a C-n'
     Execute a single line of code, stepping across entire function
     calls at full speed (`gud-next').
`C-c C-i'
`C-x C-a C-i'
     Execute a single machine instruction (`gud-stepi').
`C-c C-c'
`C-x C-a C-c'
     Continue execution until the next breakpoint, or other event that
     would normally stop the program (`gud-cont').
`C-c C-d'
`C-x C-a C-d'
     Delete the breakpoint(s) on the current source line, if any
     (`gud-remove').  If you use this command in the GUD interaction
     buffer, it applies to the line where the program last stopped.
`C-c C-t'
`C-x C-a C-t'
     Set a temporary breakpoint on the current source line, if any.  If
     you use this command in the GUD interaction buffer, it applies to
     the line where the program last stopped.
   The above commands are common to all supported debuggers.  If you are
using GDB or (some versions of) DBX, these additional commands are
available:
`C-c <'
`C-x C-a <'
     Select the next enclosing stack frame (`gud-up').  This is
     equivalent to the `up' command.
`C-c >'
`C-x C-a >'
     Select the next inner stack frame (`gud-down').  This is
     equivalent to the `down' command.
   If you are using GDB, two additional keybindings are available:
`C-c C-f'
`C-x C-a C-f'
     Run the program until the selected stack frame returns (or until it
     stops for some other reason).
   These commands interpret a prefix argument as a repeat count, when
that makes sense.
File: emacs,  Node: GUD Customization,  Prev: Commands of GUD,  Up: Debuggers
GUD Customization
-----------------
   On startup, GUD runs one of the following hooks: `gdb-mode-hook', if
you are using GDB; `dbx-mode-hook', if you are using DBX;
`sdb-mode-hook', if you are using SDB; and `xdb-mode-hook', if you are
using XDB.  You can use these hooks to define custom keybindings for
the debugger interaction buffer.  *Note Hooks::.
   Here is a convenient way to define a command that sends a particular
command string to the debugger, and set up a key binding for it in the
debugger interaction buffer:
     (gud-def FUNCTION CMDSTRING BINDING DOCSTRING)
   This defines a command named FUNCTION which sends CMDSTRING to the
debugger process, with documentation string DOCSTRING.  You can use the
command thus defined in any buffer.  If BINDING is non-`nil', `gud-def'
also binds the command to `C-c BINDING' in the GUD buffer's mode and to
`C-x C-a BINDING' generally.
   The command string CMDSTRING may contain certain escape sequences
that are filled in with varying data at the time FUNCTION is called:
     Name of the current source file.  If the current buffer is the GUD
     buffer, then the "current source file" is the file that the
     program stopped in.
     Number of the current source line.  If the current buffer is the
     GUD buffer, then the "current source line" is the line that the
     program stopped in.
     Text of the C lvalue or function-call expression surrounding point.
     Text of the hexadecimal address surrounding point.
     Prefix (numeric) argument of the called function (if any) as a
     number.  (If you don't use `%p' in the command string, the command
     you define ignores any prefix argument.)
File: emacs,  Node: Executing Lisp,  Next: Lisp Libraries,  Prev: Debuggers,  Up: Building
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.
Emacs-Lisp mode
     The mode for editing source files of programs to run in Emacs Lisp.
     This mode defines `C-M-x' to evaluate the current defun.  *Note
     Lisp Libraries::.
Lisp Interaction mode
     The mode for an interactive session with Emacs Lisp.  It defines
     LFD to evaluate the sexp before point and insert its value in the
     buffer.  *Note Lisp Interaction::.
Lisp mode
     The mode for editing source files of programs that run in Lisps
     other than Emacs Lisp.  This mode defines `C-M-x' to send the
     current defun to an inferior Lisp process.  *Note External Lisp::.
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
     (*note Shell Mode::.).
Scheme mode
     Like Lisp mode but for Scheme programs.
Inferior Scheme mode
     The mode for an interactive session with an inferior Scheme
     process.
* Menu:
These subnodes of the chapter on editing programs describe the editing
commands for working with Lisp programs, which are in fact available
globally.
* Lists::               Expressions with balanced parentheses.
* List Commands::       The commands for working with list and sexps.
* Defuns::              Each program is made up of separate functions.
                          There are editing commands to operate on them.
* Program Indent::      Adjusting indentation to show the nesting.
* Matching::            Insertion of a close-delimiter flashes matching open.
* Comments::            Inserting, killing, and aligning comments.
File: emacs,  Node: Lisp Libraries,  Next: Lisp Interaction,  Prev: Executing Lisp,  Up: Building
Libraries of Lisp Code for Emacs
================================
   Lisp code for Emacs editing commands is stored in files whose names
conventionally end in `.el'.  This ending tells Emacs to edit them in
Emacs-Lisp mode (*note Executing Lisp::.).
   To execute a file of Emacs Lisp code, use `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.
   Once a file of Lisp code is installed in the Emacs Lisp library
directories, users can load it using `M-x load-library'.  Programs can
load it by calling `load-library', or with `load', a more primitive
function that is similar but accepts some additional arguments.
   `M-x load-library' differs from `M-x load-file' in that it searches
a sequence of directories and tries three file names in each directory.
Suppose your argument is LIB; the three names are `LIB.elc', `LIB.el',
and lastly just `LIB'.  If `LIB.elc' exists, it is by convention the
result of compiling `LIB.el'; it is better to load the compiled file,
since it will load and run faster.
   If `load-library' finds that `LIB.el' is newer than `LIB.elc' file,
it prints a warning, because it's likely that somebody made changes to
the `.el' file and forgot to recompile it.
   Because the argument to `load-library' is usually not in itself a
valid file name, file name completion is not available.  Indeed, when
using this command, you usually do not know exactly what file name will
be used.
   The sequence of directories searched by `M-x load-library' is
specified by the variable `load-path', a list of strings that are
directory names.  The default value of the list contains the directory
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
`load-path'.  `nil' in this list stands for the current default
directory, but it is probably not a good idea to put `nil' in the list.
If you find yourself wishing that `nil' were in the list, most likely
what you really want to do is use `M-x load-file' this once.
   Often you do not have to give any command to load a library, because
the commands defined in the library are set up to "autoload" that
library.  Running any of those commands causes `load' to be called to
load the library; this replaces the autoload definitions with the real
ones from the library.
   If autoloading a file does not finish, either because of an error or
because of a `C-g' quit, all function definitions made by the file are
undone automatically.  So are any calls to `provide'.  As a consequence,
if you use one of the autoloadable commands again, the entire file will
be loaded a second time.  This prevents problems where the command is no
longer autoloading but it works wrong because not all the file was
loaded.  Function definitions are undone only for autoloading; explicit
calls to `load' do not undo anything if loading is not completed.
   Emacs Lisp code can be compiled into byte-code which loads faster,
takes up less space when loaded, and executes faster.  *Note Byte
Compilation: (elisp)Byte Compilation.
   By convention, the compiled code for a library goes in a separate
file whose name consists of the library source file with `c' appended.
Thus, the compiled code for `foo.el' goes in `foo.elc'.  That's why
`load-library' searches for `.elc' files first.
File: emacs,  Node: Lisp Eval,  Next: External Lisp,  Prev: Lisp Interaction,  Up: Building
Evaluating Emacs-Lisp Expressions
=================================
   Lisp programs intended to be run in Emacs should be edited in
Emacs-Lisp mode; this happens automatically for file names ending in
`.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 `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).
`M-ESC'
     Read a single Lisp expression in the minibuffer, evaluate it, and
     print the value in the echo area (`eval-expression').
`C-x C-e'
     Evaluate the Lisp expression before point, and print the value in
     the echo area (`eval-last-sexp').
`C-M-x'
     Evaluate the defun containing or after point, and print the value
     in the echo area (`eval-defun').
`M-x eval-region'
     Evaluate all the Lisp expressions in the region.
`M-x eval-current-buffer'
     Evaluate all the Lisp expressions in the buffer.
   `M-ESC' (`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 `M-ESC' was typed.
   `M-ESC' can easily confuse users who do not understand it,
especially on keyboards with autorepeat where it can result from holding
down the ESC key for too long.  Therefore, `eval-expression' is
normally a disabled command.  Attempting to use this command asks for
confirmation and gives you the option of enabling it; once you enable
the command, confirmation will no longer be required for it.  *Note
Disabling::.
   In Emacs-Lisp mode, the key `C-M-x' is bound to the command
`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.
   The command `C-x C-e' (`eval-last-sexp') performs a similar job but
is available in all major modes, not just Emacs-Lisp mode.  It finds
the sexp before point, reads it as a Lisp expression, evaluates it, and
prints the value in the echo area.  It is sometimes useful to type in an
expression and then, with point still after it, type `C-x C-e'.
   If `C-M-x' or `C-x C-e' is given a numeric argument, it prints the
value by insertion into the current buffer at point, rather than in the
echo area.  The argument value does not matter.
   The most general command for evaluating Lisp expressions from a
buffer is `eval-region'.  `M-x eval-region' parses the text of the
region as one or more Lisp expressions, evaluating them one by one.
`M-x eval-current-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 just ready to test.  After finding and fixing a bug, use
`C-M-x' on each function that you change, to keep the Lisp world in
step with the source file.
File: emacs,  Node: Lisp Interaction,  Next: Lisp Eval,  Prev: Lisp Libraries,  Up: Building
Lisp Interaction Buffers
========================
   The buffer `*scratch*' which is selected when Emacs starts up is
provided for evaluating Lisp expressions interactively inside Emacs.
   Thus, the way to use the `*scratch*' buffer is to insert Lisp
expressions at the end, ending each one with LFD so that it will be
evaluated.  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.
   The `*scratch*' buffer's major mode is Lisp Interaction mode, which
is the same as Emacs-Lisp mode except for the binding of LFD.
   The rationale for this feature is that Emacs must have a buffer when
it starts up, but that buffer is not useful for editing files since a
new buffer is made for every file that you visit.  The Lisp interpreter
typescript is the most useful thing I can think of for the initial
buffer to do.  Type `M-x lisp-interaction-mode' to put the current
buffer in Lisp Interaction mode.
File: emacs,  Node: External Lisp,  Prev: Lisp Eval,  Up: Building
Running an External 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.
   To run an inferior Lisp process, type `M-x run-lisp'.  This runs the
program named `lisp', the same program you would run by typing `lisp'
as a shell command, with both input and output going through an Emacs
buffer named `*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 `inferior-lisp-program'.)
   To give input to Lisp, go to the end of the buffer and type the
input, terminated by RET.  The `*lisp*' buffer is in Inferior Lisp
mode, which combines the special characteristics of Lisp mode and Shell
mode (*note Shell Mode::.).
   For the source files of programs to run in external Lisps, use Lisp
mode.  This mode can be selected with `M-x lisp-mode', and is used
automatically for files whose names end in `.l' or `.lisp', as most Lisp
systems usually expect.
   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 `C-M-x'.  In Lisp mode, this runs the function
`lisp-send-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 `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): 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.  *Note Executing Lisp::.
File: emacs,  Node: Abbrevs,  Next: Picture,  Prev: Building,  Up: Top
Abbrevs
*******
   An "abbrev" is a word which "expands", if you insert it, into some
different text.  Abbrevs are defined by the user to expand in specific
ways.  For example, you might define `foo' as an abbrev expanding to
`find outer otter'.  With this abbrev defined, you would be able to get
`find outer otter ' into the buffer by typing `f o o SPC'.
   Abbrevs expand only when Abbrev mode (a minor mode) is enabled.
Disabling Abbrev mode does not cause abbrev definitions to be forgotten,
but they do not expand until Abbrev mode is enabled again.  The command
`M-x abbrev-mode' toggles Abbrev mode; with a numeric argument, it
turns Abbrev mode on if the argument is positive, off otherwise.  *Note
Minor Modes::.  `abbrev-mode' is also a variable; Abbrev mode is on
when the variable is non-`nil'.  The variable `abbrev-mode'
automatically becomes local to the current buffer when it is set.
   Abbrev definitions can be "mode-specific"--active only in one major
mode.  Abbrevs can also have "global" definitions that are active in
all major modes.  The same abbrev can have a global definition and
various mode-specific definitions for different major modes.  A mode
specific definition for the current major mode overrides a global
definition.
   Abbrevs can be defined interactively during the editing session.
Lists of abbrev definitions can also be saved in files and reloaded in
later sessions.  Some users keep extensive lists of abbrevs that they
load in every session.
   A second kind of abbreviation facility is called the "dynamic
expansion".  Dynamic abbrev expansion happens only when you give an
explicit command and the result of the expansion depends only on the
current contents of the buffer.  *Note Dynamic Abbrevs::.
* Menu:
* Defining Abbrevs::  Defining an abbrev, so it will expand when typed.
* Expanding Abbrevs:: Controlling expansion: prefixes, canceling expansion.
* Editing Abbrevs::   Viewing or editing the entire list of defined abbrevs.
* Saving Abbrevs::    Saving the entire list of abbrevs for another session.
* Dynamic Abbrevs::   Abbreviations for words already in the buffer.
File: emacs,  Node: Defining Abbrevs,  Next: Expanding Abbrevs,  Up: Abbrevs
Defining Abbrevs
================
`C-x a g'
     Define an abbrev, using one or more words before point as its
     expansion (`add-global-abbrev').
`C-x a l'
     Similar, but define an abbrev specific to the current major mode
     (`add-mode-abbrev').
`C-x a i g'
     Define a word in the buffer as an abbrev
     (`inverse-add-global-abbrev').
`C-x a i l'
     Define a word in the buffer as a mode-specific abbrev
     (`inverse-add-mode-abbrev').
`M-x kill-all-abbrevs'
     After this command, there are no abbrev definitions in effect.
   The usual way to define an abbrev is to enter the text you want the
abbrev to expand to, position point after it, and type `C-x a g'
(`add-global-abbrev').  This reads the abbrev itself using the
minibuffer, and then defines it as an abbrev for one or more words
before point.  Use a numeric argument to say how many words before
point should be taken as the expansion.  For example, to define the
abbrev `foo' as mentioned above, insert the text `find outer otter' and
then type `C-u 3 C-x a g f o o RET'.
   An argument of zero to `C-x a g' means to use the contents of the
region as the expansion of the abbrev being defined.
   The command `C-x a l' (`add-mode-abbrev') is similar, but defines a
mode-specific abbrev.  Mode specific abbrevs are active only in a
particular major mode.  `C-x a l' defines an abbrev for the major mode
in effect at the time `C-x a l' is typed.  The arguments work the same
as for `C-x a g'.
   If the text of the abbrev you want is already in the buffer instead
of the expansion, use command `C-x a i g' (`inverse-add-global-abbrev')
instead of `C-x a g', or use `C-x a i l' (`inverse-add-mode-abbrev')
instead of `C-x a l'.  These commands are called "inverse" because they
invert the meaning of the argument found in the buffer and the argument
read using the minibuffer.
   To change the definition of an abbrev, just add the new definition.
You will be asked to confirm if the abbrev has a prior definition.  To
remove an abbrev definition, give a negative argument to `C-x a g' or
`C-x a l'.  You must choose the command to specify whether to kill a
global definition or a mode-specific definition for the current mode,
since those two definitions are independent for one abbrev.
   `M-x kill-all-abbrevs' removes all the abbrev definitions there are.
File: emacs,  Node: Expanding Abbrevs,  Next: Editing Abbrevs,  Prev: Defining Abbrevs,  Up: Abbrevs
Controlling Abbrev Expansion
============================
   An abbrev expands whenever it is present in the buffer just before
point and a self-inserting punctuation character (SPC, comma, etc.) is
typed.  Most often the way an abbrev is used is to insert the abbrev
followed by punctuation.
   Abbrev expansion preserves case; thus, `foo' expands into `find
outer otter'; `Foo' into `Find outer otter', and `FOO' into `FIND OUTER
OTTER' or `Find Outer Otter' according to the variable
`abbrev-all-caps' (a non-`nil' value chooses the first of the two
expansions).
   These two commands are used to control abbrev expansion:
`M-''
     Separate a prefix from a following abbrev to be expanded
     (`abbrev-prefix-mark').
`C-x a e'
     Expand the abbrev before point (`expand-abbrev').  This is
     effective even when Abbrev mode is not enabled.
`M-x unexpand-abbrev'
     Undo last abbrev expansion.
`M-x expand-region-abbrevs'
     Expand some or all abbrevs found in the region.
   You may wish to expand an abbrev with a prefix attached; for
example, if `cnst' expands into `construction', you might want to use
it to enter `reconstruction'.  It does not work to type `recnst',
because that is not necessarily a defined abbrev.  What does work is to
use the command `M-'' (`abbrev-prefix-mark') in between the prefix `re'
and the abbrev `cnst'.  First, insert `re'.  Then type `M-''; this
inserts a minus sign in the buffer to indicate that it has done its
work.  Then insert the abbrev `cnst'; the buffer now contains
`re-cnst'.  Now insert a punctuation character to expand the abbrev
`cnst' into `construction'.  The minus sign is deleted at this point,
because `M-'' left word for this to be done.  The resulting text is the
desired `reconstruction'.
   If you actually want the text of the abbrev in the buffer, rather
than its expansion, you can accomplish this by inserting the following
punctuation with `C-q'.  Thus, `foo C-q -' leaves `foo-' in the buffer.
   If you expand an abbrev by mistake, you can undo the expansion
(replace the expansion by the original abbrev text) with `M-x
unexpand-abbrev'.  `C-_' (`undo') can also be used to undo the
expansion; but first it undoes the insertion of the following
punctuation character.  Therefore, if you want both the punctuation
character and the unexpanded abbrev, you must reinsert the punctuation
character, quoting it with `C-q'.
   `M-x expand-region-abbrevs' searches through the region for defined
abbrevs, and for each one found offers to replace it with its expansion.
This command is useful if you have typed in text using abbrevs but
forgot to turn on Abbrev mode first.  It may also be useful together
with a special set of abbrev definitions for making several global
replacements at once.  This command is effective even if Abbrev mode is
not enabled.
   Expanding an abbrev runs the hook `pre-abbrev-expand-hook' (*note
Hooks::.).
File: emacs,  Node: Editing Abbrevs,  Next: Saving Abbrevs,  Prev: Expanding Abbrevs,  Up: Abbrevs
Examining and Editing Abbrevs
=============================
`M-x list-abbrevs'
     Print a list of all abbrev definitions.
`M-x edit-abbrevs'
     Edit a list of abbrevs; you can add, alter or remove definitions.
   The output from `M-x list-abbrevs' looks like this:
     (lisp-mode-abbrev-table)
     "dk"	       0    "define-key"
     (global-abbrev-table)
     "dfn"	       0    "definition"
(Some blank lines of no semantic significance, and some other abbrev
tables, have been omitted.)
   A line containing a name in parentheses is the header for abbrevs in
a particular abbrev table; `global-abbrev-table' contains all the global
abbrevs, and the other abbrev tables that are named after major modes
contain the mode-specific abbrevs.
   Within each abbrev table, each nonblank line defines one abbrev.  The
word at the beginning is the abbrev.  The number that appears is the
number of times the abbrev has been expanded.  Emacs keeps track of
this to help you see which abbrevs you actually use, in case you decide
to eliminate those that you don't use often.  The string at the end of
the line is the expansion.
   `M-x edit-abbrevs' allows you to add, change or kill abbrev
definitions by editing a list of them in an Emacs buffer.  The list has
the same format described above.  The buffer of abbrevs is called
`*Abbrevs*', and is in Edit-Abbrevs mode.  This mode redefines the key
`C-c C-c' to install the abbrev definitions as specified in the buffer.
The command that does this is `edit-abbrevs-redefine'.  Any abbrevs
not described in the buffer are eliminated when this is done.
   The command `edit-abbrevs' is actually the same as `list-abbrevs'
except that it selects the buffer `*Abbrevs*' whereas `list-abbrevs'
merely displays it in another window.