====== Request for Comments: Indirect method call by array variable ======
  * Version: 1.0
  * Date: 2011-06-05
  * Author: Felipe Pena <felipe@php.net>
  * Status: Implemented
  * Published in internals: http://markmail.org/thread/apqqa5lkuuedbbjf


===== Introduction =====

Reading our bug tracker I noticed a good feature request (http://bugs.php.net/bug.php?id=47160) from 2009 which points to an interesting feature that I think makes sense for us, since we are now working with $f() using objects and strings, and the array('class', 'method') is an old known for call_user_func()-like functions.

The array to be a valid callback should be a 2-element array, and it must be for the first element object/string and for the second string only. (just like our zend_is_callable() check and opcodes related to init call)

===== Example =====

<code php>
<?php

class Hello {
   public function world($x) {
      echo "Hello, $x\n"; return $this;
   }
}


$f = array('Hello','world');
var_dump($f('you')); // Hello, you

?>
</code>

Checking for callback, nowadays already recognizes array('class', 'method') as valid callback, so it will facility the indirect call through a variable:

<code php>
<?php


class Hello {
   static public function world($x) {
     echo "Hello, $x\n";
   }
}


function hello_world($x) {
   echo "Hello, $x\n";
}


$callbacks = array(
   array('Hello', 'world'),
   function ($x) { echo "Hello, $x\n"; },
   'hello_world'
);


foreach ($callbacks as $k => $callback) {
   if (is_callable($callback)) {
     $callback($k);
   }
}

?>
</code>

Output:
<code>
Hello, 0
Hello, 1
Hello, 2
</code>


===== Patch =====

  -  http://felipe.ath.cx/diff/fr47160.diff