====== Request for Comments: Function autoloading through spl_autoload* ======
  * Version: 1.0
  * Date: 2011-08-05
  * Author: Ferenc Kovacs <tyra3l@gmail.com>
  * Status: Inactive
  * First Published at: https://wiki.php.net/rfc/autofunc


===== Introduction =====

The topic of supporting function autoloading was brought up many times in the past, this RFC introduces a potential implementation which would be consistent with what we have for autoloading classes. 

===== Proposal =====

The suggested change would be pretty straightforward and BC compatible:
  * Add two new constants to spl: SPL_AUTOLOAD_CLASS, SPL_AUTOLOAD_FUNCTION. 
  * Add a fourth optional parameter for spl_autoload_register called $types with the default value of SPL_AUTOLOAD_CLASS (this would keep the BC), supported values would be any combination of SPL_AUTOLOAD_CLASS and SPL_AUTOLOAD_FUNCTION for now.
    * As you would guess, this would work the same way as the $error_types parameter works for set_error_handler: you can specify for which type(s) of missing tokens the autoloader should be called.
  * The type for the missing token should also be passed to the $autoload_function callback as a second param.
    * This is needed to be able to handle multiple types of tokens with a common callback.
    * Note that passing more parameters to a function than it has in its definition is valid, this would also be a backward compatible change.
  * Change the current class autoloading to only call the autoloaders which match with the SPL_AUTOLOAD_CLASS types.
  * Add the function autoloading to only call the autoloaders which match with the SPL_AUTOLOAD_FUNCTION types.

==== Future improvements ====

Notice that currently only functions are proposed, but we could implement autoloading other tokens (SPL_AUTOLOAD_CONSTANT, etc.) with this interface.

==== Examples ====
<code php>
 <?php
 // old behavior
 spl_autoload_register(
  function ($name) {
   // include the class definition
   /* ... */
  }
 );

 // autoload functions
 spl_autoload_register(
  function ($name) {
   // include the function definition
   /* ... */
  },
  true,
  false,
  SPL_AUTOLOAD_FUNCTION
 );

 // autoload mixed
 spl_autoload_register(
  function ($name, $type) {
   switch($type){
    case SPL_AUTOLOAD_CLASS:
     /* ... */
     break;
    case SPL_AUTOLOAD_FUNCTION:
     /* ... */
     break;      
   }
  },
  true,
  false,
  SPL_AUTOLOAD_CLASS|SPL_AUTOLOAD_FUNCTION
 );
</code>


==== Patch ====

Patches welcome! :)

==== Related RFCs ====
  * [[rfc:autodefine|RFC __autodefine]]

==== Related discussions ====
  * [[http://www.mail-archive.com/internals@lists.php.net/msg43983.html]]
  * [[http://www.mail-archive.com/internals@lists.php.net/msg48986.html]]
  * [[http://www.mail-archive.com/internals@lists.php.net/msg52287.html]]
  * [[http://www.mail-archive.com/internals@lists.php.net/msg48820.html]]

==== Changelog ====
 * 2011.08.17 - replace the T_* constants with SPL_AUTOLOAD_*