private function getInstanceHelper($config)
    {
        if (is_callable($config)) {
            return $config;
        }
        if (!isset($config['class_name'])) {
            throw new Exception\RuntimeException('Config router convert miss "class_name"');
        }
        $className = $config['class_name'];
        if (!class_exists($className)) {
            throw new Exception\RuntimeException(sprintf('"%s" is not existed', $className));
        }

        /**
         * @todo User can config parameter when create new object
         * @todo User can config call method after creating object
         */
        $object = new $className;

        return $object;
    }