@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999,
-@c 2003, 2004, 2005
-@c Free Software Foundation, Inc.
+@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2003,
+@c 2004, 2005, 2006 Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../info/loading
@node Loading, Byte Compilation, Customization, Top
file, reads the text, evaluates each form, and then closes the file.
The load functions evaluate all the expressions in a file just
-as the @code{eval-current-buffer} function evaluates all the
+as the @code{eval-buffer} function evaluates all the
expressions in a buffer. The difference is that the load functions
read and evaluate the text in the file as found on disk, not the text
in an Emacs buffer.
@menu
* How Programs Do Loading:: The @code{load} function and others.
+* Load Suffixes:: Details about the suffixes that @code{load} tries.
* Library Search:: Finding a library to load.
* Loading Non-ASCII:: Non-@acronym{ASCII} characters in Emacs Lisp files.
* Autoload:: Setting up a function to autoload.
* Repeated Loading:: Precautions about loading a file twice.
* Named Features:: Loading a library if it isn't already loaded.
* Where Defined:: Finding which file defined a certain symbol.
-* Unloading:: How to ``unload'' a library that was loaded.
+* Unloading:: How to "unload" a library that was loaded.
* Hooks for Loading:: Providing code to be run when
particular libraries are loaded.
@end menu
@var{filename}. In the perverse case of a file named @file{foo.el.el},
evaluation of @code{(load "foo.el")} will indeed find it.)
-If the optional argument @var{nosuffix} is non-@code{nil}, then the
-suffixes @samp{.elc} and @samp{.el} are not tried. In this case, you
-must specify the precise file name you want. By specifying the precise
-file name and using @code{t} for @var{nosuffix}, you can prevent
-perverse file names such as @file{foo.el.el} from being tried.
+If Auto Compression mode is enabled, as it is by default, then
+if @code{load} can not find a file, it searches for a compressed
+version of the file before trying other file names. It decompresses
+and loads it if it exists. It looks for compressed versions by
+appending the suffixes in @code{jka-compr-load-suffixes} to the file
+name. The value of this variable must be a list of strings. Its
+standard value is @code{(".gz")}.
+
+If the optional argument @var{nosuffix} is non-@code{nil}, then
+@code{load} does not try the suffixes @samp{.elc} and @samp{.el}. In
+this case, you must specify the precise file name you want, except
+that, if Auto Compression mode is enabled, @code{load} will still use
+@code{jka-compr-load-suffixes} to find compressed versions. By
+specifying the precise file name and using @code{t} for
+@var{nosuffix}, you can prevent perverse file names such as
+@file{foo.el.el} from being tried.
If the optional argument @var{must-suffix} is non-@code{nil}, then
@code{load} insists that the file name used must end in either
-@samp{.el} or @samp{.elc}, unless it contains an explicit directory
-name. If @var{filename} does not contain an explicit directory name,
-and does not end in a suffix, then @code{load} insists on adding one.
+@samp{.el} or @samp{.elc} (possibly extended with a compression
+suffix), unless it contains an explicit directory name.
If @var{filename} is a relative file name, such as @file{foo} or
@file{baz/foo.bar}, @code{load} searches for the file using the variable
@deffn Command load-file filename
This command loads the file @var{filename}. If @var{filename} is a
relative file name, then the current default directory is assumed.
-@code{load-path} is not used, and suffixes are not appended. Use this
-command if you wish to specify precisely the file name to load.
+This command does not use @code{load-path}, and does not append
+suffixes. However, it does look for compressed versions (if Auto
+Compression Mode is enabled). Use this command if you wish to specify
+precisely the file name to load.
@end deffn
@deffn Command load-library library
@end defvar
@defvar load-read-function
+This
@anchor{Definition of load-read-function}
-This variable specifies an alternate expression-reading function for
+@c do not allow page break at anchor; work around Texinfo deficiency.
+variable specifies an alternate expression-reading function for
@code{load} and @code{eval-region} to use instead of @code{read}.
The function should accept one argument, just as @code{read} does.
For information about how @code{load} is used in building Emacs, see
@ref{Building Emacs}.
+@node Load Suffixes
+@section Load Suffixes
+We now describe some technical details about the exact suffixes that
+@code{load} tries.
+
+@defvar load-suffixes
+This is a list of suffixes indicating (compiled or source) Emacs Lisp
+files. It should not include the empty string. @code{load} uses
+these suffixes in order when it appends Lisp suffixes to the specified
+file name. The standard value is @code{(".elc" ".el")} which produces
+the behavior described in the previous section.
+@end defvar
+
+@defvar load-file-rep-suffixes
+This is a list of suffixes that indicate representations of the same
+file. This list should normally start with the empty string.
+When @code{load} searches for a file it appends the suffixes in this
+list, in order, to the file name, before searching for another file.
+
+Enabling Auto Compression mode appends the suffixes in
+@code{jka-compr-load-suffixes} to this list and disabling Auto
+Compression mode removes them again. The standard value of
+@code{load-file-rep-suffixes} if Auto Compression mode is disabled is
+@code{("")}. Given that the standard value of
+@code{jka-compr-load-suffixes} is @code{(".gz")}, the standard value
+of @code{load-file-rep-suffixes} if Auto Compression mode is enabled
+is @code{("" ".gz")}.
+@end defvar
+
+@defun get-load-suffixes
+This function returns the list of all suffixes that @code{load} should
+try, in order, when its @var{must-suffix} argument is non-@code{nil}.
+This takes both @code{load-suffixes} and @code{load-file-rep-suffixes}
+into account. If @code{load-suffixes}, @code{jka-compr-load-suffixes}
+and @code{load-file-rep-suffixes} all have their standard values, this
+function returns @code{(".elc" ".elc.gz" ".el" ".el.gz")} if Auto
+Compression mode is enabled and @code{(".elc" ".el")} if Auto
+Compression mode is disabled.
+@end defun
+
+To summarize, @code{load} normally first tries the suffixes in the
+value of @code{(get-load-suffixes)} and then those in
+@code{load-file-rep-suffixes}. If @var{nosuffix} is non-@code{nil},
+it skips the former group, and if @var{must-suffix} is non-@code{nil},
+it skips the latter group.
+
@node Library Search
@section Library Search
tells @code{locate-library} to display the file name in the echo area.
@end deffn
-@defvar load-suffixes
-This variable is a list of suffixes (strings) that @code{load} should
-try adding to the specified file name. The default value is
-@code{(".elc" ".el")}. There is no need to include the null suffix.
-@end defvar
-
@node Loading Non-ASCII
@section Loading Non-@acronym{ASCII} Characters
If @var{filename} does not contain either a directory name, or the
suffix @code{.el} or @code{.elc}, then @code{autoload} insists on adding
one of these suffixes, and it will not load from a file whose name is
-just @var{filename} with no added suffix.
+just @var{filename} with no added suffix. (The variable
+@code{load-suffixes} specifies the exact required suffixes.)
The argument @var{docstring} is the documentation string for the
function. Specifying the documentation string in the call to
with @code{load}. If @var{filename} is not supplied, then the name of
the symbol @var{feature} is used as the base file name to load.
However, in this case, @code{require} insists on finding @var{feature}
-with an added suffix; a file whose name is just @var{feature} won't be
-used.
+with an added @samp{.el} or @samp{.elc} suffix (possibly extended with
+a compression suffix); a file whose name is just @var{feature} won't
+be used. (The variable @code{load-suffixes} specifies the exact
+required Lisp suffixes.)
If @var{noerror} is non-@code{nil}, that suppresses errors from actual
loading of the file. In that case, @code{require} returns @code{nil}
acceptable. If @var{type} is @code{defun} or @code{defvar}, that
specifies function definition only or variable definition only.
-The value is the file name as it was specified to @code{load}:
-either an absolute file name, or a library name
-(with no directory name and no @samp{.el} or @samp{.elc} at the end).
-It can also be @code{nil}, if the definition is not associated with any file.
+The value is normally an absolute file name. It can also be
+@code{nil}, if the definition is not associated with any file.
@end defun
The basis for @code{symbol-file} is the data in the variable
@code{load-history}.
@defvar load-history
-This variable's value is an alist connecting library names with the
+This variable's value is an alist connecting library file names with the
names of functions and variables they define, the features they provide,
and the features they require.
Each element is a list and describes one library. The @sc{car} of the
-list is the name of the library, as a string. The rest of the list
-elements have these forms:
+list is the absolute file name of the library, as a string. The rest
+of the list elements have these forms:
@table @code
@item @var{var}