public static function set_sort_direction($sort_direction) { if ($sort_direction == 'ASC') { Model_Kwalbum_Comment::$_sort_direction = 'ASC'; Model_Kwalbum_Comment::$_gtlt = '<'; } else { Model_Kwalbum_Comment::$_sort_direction = 'DESC'; Model_Kwalbum_Comment::$_gtlt = '>'; } }