discuz宣言类难道还有另类的方法吗

C::creatapp();

class core
{
	private static $_tables;
	private static $_imports;
	private static $_app;
	private static $_memory;

	public static function app() {
		return self::$_app;
	}

	public static function creatapp() {
		if(!is_object(self::$_app)) {
			self::$_app = discuz_application::instance();
		}
		return self::$_app;
	}