class X {
    private $message = 'Main class';
    public function __destruct()
    {
        echo 'Object ob class "'. __METHOD__ .'" is destroyed!<br>';
        echo $this->message . '<br>';
    }
}
class Y extends X {
    public function __destruct(){
        echo __METHOD__ . '<br><br>';
    }
}

$x = new X;
$y = new Y;