public static function apply($class, $method, $filter) {
		list($id,) = static::_ids($class, $method);

		if (!isset(static::$_filters[$id])) {
			static::$_filters[$id] = [];
		}
		static::$_filters[$id][] = $filter;

		if (isset(static::$_chains[$id])) {
			unset(static::$_chains[$id]);
		}
	}