Accessing static private variable hack using closure.

how_to_access_static_private_variable_destructively.php

<?php
class Sample
{
    static private $value = 0;
    static function privateHack() {
        $hack =& static::$value;
        return function($val) use (&$hack) {
            $hack = $val;
        };
    }
    static function show() {
        echo static::$value;
    }
}

$hack = Sample::privateHack();
$hack(10);

Sample::show(); // => 10