Description:
------------
Object callbacks $foo->bar() are represented as arrays array($foo, 'bar'). Since PHP now supports the syntax $foo->bar->baz(), it seems at first sight that callback arrays could be nested similarly.

Currently to use the baz() method above in a callback, one must use a temporary variable $temp=$foo->bar, and use array($temp, 'baz') as the callback in the same way that in PHP4 it was necessary to write $temp=$foo->bar; $temp->baz().

It would seem syntactically unambiguous to write the callback as array(array($foo, 'bar'), 'baz'). There is the matter that its first element refers to an object, not a method, but that's what the first element of an array callback is supposed to refer to (static class methods notwithstanding).

Reproduce code:
---------------
<?php
class aclass
{
	public $b;
}
class bclass
{
	public function foo($v)
	{
		return $v*2;
	}
}

$t = array('1','2','3','4','5','6','7','8','9');

$a = new aclass;
$a->b = new bclass;
print_r(array_map(array(array($a, 'b') ,'foo'), $t));

Expected result:
----------------
Array
(
    [0] => 2
    [1] => 4
    [2] => 6
    [3] => 8
    [4] => 10
    [5] => 12
    [6] => 14
    [7] => 16
    [8] => 18
)

Actual result:
--------------
Warning: array_map(): The first argument, 'Array', should be either NULL or a valid callback in ...