/** 2.Singleton*/class Singleton{	private static $instance = null;	public static function getInstance(){		if (!isset(self::$instance)){              $c = __CLASS__;              self::$instance = new $c;           }  		return self::$instance;	}	public function eventResult($id){		return $id;	}	protected function __construct()    {    }    private function __clone()    {    }    private function __wakeup()    {    }}class SingletonChild extends Singleton{}$obj = Singleton::getInstance();var_dump($obj === Singleton::getInstance());           $anotherObj = SingletonChild::getInstance();var_dump($anotherObj === Singleton::getInstance());     var_dump($anotherObj === SingletonChild::getInstance()); $objSingle = Singleton::getInstance();$result = $objSingle->eventResult(100);print_r($result);