#define SS_ASSERT_CLASS(_obj_,_cls_) do {                                                                                      \
     if (!(_obj_) || SS_MAGIC_CLASS(SS_MAGIC_OF(_obj_))!=SS_MAGIC_CLASS(SS_MAGIC(_cls_)))                                       \
         SS_ERROR_FMT(TYPE, ("%s should be class %s", #_obj_, #_cls_))                                                          \
 } while (false);