public static function getInstance()
    {
        if (!isset(self::$_instance)) {
            $c = __CLASS__;
            self::$_instance = new $c;
        }
        return self::$_instance;
    }
public static function getInstance()
    {
        if (!isset(self::$_instance)) {
            $c = __CLASS__;
            self::$_instance = new $c;
        }
        return self::$_instance;
    }
public static function getInstance ( ) { if ( ! isset ( self :: $ _instance ) ) { $ c = __CLASS__ ; self :: $ _instance = new $ c ; } return self :: $ _instance ; }
Get cache instance

@return mixed cache
Get cache instance