private static function createInstance($classname, array $arguments = array())
    {
        $reflection_obj = new ReflectionClass($classname);
        if ($reflection_obj->getMethod('__construct')->isPublic()) {
            self::$_instances[ $classname ] = call_user_func_array(array($reflection_obj, 'newInstance'), $arguments);
            if (
                method_exists(self::$_instances[ $classname ], 'init') &&
                is_callable(array(self::$_instances[ $classname ], 'init'))
            ) {
                self::$_instances[ $classname ]->init();
            }
        } else {
            self::$_instances[ $classname ] = new $classname;
            if (
                method_exists(self::$_instances[ $classname ], 'init') &&
                is_callable(array(self::$_instances[ $classname ], 'init'))
            ) {
                call_user_func_array(array(self::$_instances[ $classname ], 'init'), $arguments);
            }
        }
    }