[php学习]单例模式

/** 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);