Info Catalog eintr: Loading Files eintr: Emacs Initialization eintr: Simple Extension

eintr: Autoload

 
 16.10 Autoloading
 =================
 
 Instead of installing a function by loading the file that contains it,
 or by evaluating the function definition, you can make the function
 available but not actually install it until it is first called.  This is
 called “autoloading”.
 
    When you execute an autoloaded function, Emacs automatically
 evaluates the file that contains the definition, and then calls the
 function.
 
    Emacs starts quicker with autoloaded functions, since their libraries
 are not loaded right away; but you need to wait a moment when you first
 use such a function, while its containing file is evaluated.
 
    Rarely used functions are frequently autoloaded.  The ‘loaddefs.el’
 library contains thousands of autoloaded functions, from ‘5x5’ to
 ‘zone’.  Of course, you may come to use a rare function frequently.
 When you do, you should load that function’s file with a ‘load’
 expression in your ‘.emacs’ file.
 
    In my ‘.emacs’ file, I load 14 libraries that contain functions that
 would otherwise be autoloaded.  (Actually, it would have been better to
 include these files in my dumped Emacs, but I forgot.  Building
 Emacs (elisp)Building Emacs, and the ‘INSTALL’ file for more about
 dumping.)
 
    You may also want to include autoloaded expressions in your ‘.emacs’
 file.  ‘autoload’ is a built-in function that takes up to five
 arguments, the final three of which are optional.  The first argument is
 the name of the function to be autoloaded; the second is the name of the
 file to be loaded.  The third argument is documentation for the
 function, and the fourth tells whether the function can be called
 interactively.  The fifth argument tells what type of object—‘autoload’
 can handle a keymap or macro as well as a function (the default is a
 function).
 
    Here is a typical example:
 
      (autoload 'html-helper-mode
        "html-helper-mode" "Edit HTML documents" t)
 
 (‘html-helper-mode’ is an older alternative to ‘html-mode’, which is a
 standard part of the distribution.)
 
 This expression autoloads the ‘html-helper-mode’ function.  It takes it
 from the ‘html-helper-mode.el’ file (or from the byte compiled version
 ‘html-helper-mode.elc’, if that exists.)  The file must be located in a
 directory specified by ‘load-path’.  The documentation says that this is
 a mode to help you edit documents written in the HyperText Markup
 Language.  You can call this mode interactively by typing ‘M-x
 html-helper-mode’.  (You need to duplicate the function’s regular
 documentation in the autoload expression because the regular function is
 not yet loaded, so its documentation is not available.)
 
    Autoload (elisp)Autoload, for more information.
 

Info Catalog eintr: Loading Files eintr: Emacs Initialization eintr: Simple Extension