Emacs Lisp has several interfaces for loading. For example,
autoload creates a placeholder object for a function defined in a
file; trying to call the autoloading function loads the file to get the
function's real definition (see Autoload).
require loads a
file if it isn't already loaded (see Named Features). Ultimately,
all these facilities call the
load function to do the work.
This function finds and opens a file of Lisp code, evaluates all the forms in it, and closes the file.
To find the file,
loadfirst looks for a file named filename.elc, that is, for a file whose name is filename with the extension ‘.elc’ appended. If such a file exists, it is loaded. If there is no file by that name, then
loadlooks for a file named filename.el. If that file exists, it is loaded. Finally, if neither of those names is found,
loadlooks for a file named filename with nothing appended, and loads it if it exists. (The
loadfunction is not clever about looking at filename. In the perverse case of a file named foo.el.el, evaluation of
(load "foo.el")will indeed find it.)
If Auto Compression mode is enabled, as it is by default, then if
loadcan 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 each of the suffixes in
jka-compr-load-suffixesto the file name. The value of this variable must be a list of strings. Its standard value is
If the optional argument nosuffix is non-
loaddoes not try the suffixes ‘.elc’ and ‘.el’. In this case, you must specify the precise file name you want, except that, if Auto Compression mode is enabled,
loadwill still use
jka-compr-load-suffixesto find compressed versions. By specifying the precise file name and using
tfor nosuffix, you can prevent file names like foo.el.el from being tried.
If the optional argument must-suffix is non-
loadinsists that the file name used must end in either ‘.el’ or ‘.elc’ (possibly extended with a compression suffix), unless it contains an explicit directory name.
If the option
nil, then when searching suffixes,
loadselects whichever version of a file (‘.elc’, ‘.el’, etc.) has been modified most recently.
If filename is a relative file name, such as foo or baz/foo.bar,
loadsearches for the file using the variable
load-path. It appends filename to each of the directories listed in
load-path, and loads the first file it finds whose name matches. The current default directory is tried only if it is specified in
nilstands for the default directory.
loadtries all three possible suffixes in the first directory in
load-path, then all three suffixes in the second directory, and so on. See Library Search.
Whatever the name under which the file is eventually found, and the directory where Emacs found it, Emacs sets the value of the variable
load-file-nameto that file's name.
If you get a warning that foo.elc is older than foo.el, it means you should consider recompiling foo.el. See Byte Compilation.
When loading a source file (not compiled),
loadperforms character set translation just as Emacs would do when visiting the file. See Coding Systems.
When loading an uncompiled file, Emacs tries to expand any macros that the file contains (see Macros). We refer to this as eager macro expansion. Doing this (rather than deferring the expansion until the relevant code runs) can significantly speed up the execution of uncompiled code. Sometimes, this macro expansion cannot be done, owing to a cyclic dependency. In the simplest example of this, the file you are loading refers to a macro defined in another file, and that file in turn requires the file you are loading. This is generally harmless. Emacs prints a warning (‘Eager macro-expansion skipped due to cycle...’) giving details of the problem, but it still loads the file, just leaving the macro unexpanded for now. You may wish to restructure your code so that this does not happen. Loading a compiled file does not cause macroexpansion, because this should already have happened during compilation. See Compiling Macros.
Messages like ‘Loading foo...’ and ‘Loading foo...done’ appear in the echo area during loading unless nomessage is non-
You can use the variable
load-read-functionto specify a function for
loadto use instead of
readfor reading expressions. See below.
tif the file loads successfully.
This command loads the file filename. If filename is a relative file name, then the current default directory is assumed. This command does not use
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.
This command loads the library named library. It is equivalent to
load, except for the way it reads its argument interactively. See Lisp Libraries.
This variable is non-
nilif Emacs is in the process of loading a file, and it is
When Emacs is in the process of loading a file, this variable's value is the name of that file, as Emacs found it during the search described earlier in this section.
Normally, the variable's value is
nil, which means those functions should use
Instead of using this variable, it is cleaner to use another, newer feature: to pass the function as the read-function argument to
eval-region. See Eval.
For information about how
load is used in building Emacs, see