class Asd { static $x = 2; static $y = null; static $z = null; function heh() { self::$y = "asd"; } function foo() { return isset(self::$x); } function bar() { return isset(self::$y); } function baz() { return isset(self::$z); } } $y = new Asd(); var_dump($y->foo()); var_dump($y->bar()); var_dump($y->baz()); $y->heh(); var_dump($y->foo()); var_dump($y->bar()); var_dump($y->baz());