Description:
------------
Please consider including this function in the standard library:

http://us3.php.net/rename_function

This would enable techniques as shown below.

I know this is a duplicate of feature request #37078, which was bluntly rejected without explanation, before anyone had a chance to review or comment on this idea.

Reproduce code:
---------------
<?php

// example -
// install an autoload handler that preserves an existing handler:

if (function_exists('__autoload')) {
  rename_function('__autoload', '__autoload_old');
}

function __autoload($class_name) {
  if (function_exists('__autoload_old') {
    try {
      __autoload_old($class_name);
    catch ($e) {
      // my own autoloader here..
    }
  }
}

?>

Another example would be the ability to extend existing PHP functions with new functionality, like calculating default arguments or enhancing the behavior of certain functions. Example: the array_chunk function only works with real arrays - you could override it with a function that works with iterable objects as well.

Expected result:
----------------
This would work - you could override this magic function and preserve any existing autoloader.

This would enable you to combine autoloaders from different projects.

Actual result:
--------------
The function is not generally available on standard PHP installations.