<?php

class foo {
    private $test = 3;
    public $a;

    public function x() {
        $a = &$this;
        $this->a = function() use (&$a) { return $a; };
        var_dump($this->a->__invoke());
        var_dump(is_a($this->a, 'closure'));
        var_dump(is_callable($this->a));

        return $this->a;
    }
}

$foo = new foo;
$y = $foo->x();
var_dump($y()->test);

?>