...

include/pocketpy/cffi.h

@@ -16,12 +16,12 @@ namespace pkpy {
             vm->TypeError("expected '" #mod "." #name "', got " + OBJ_NAME(vm->_t(val)).escape());  \
         }                                                                   \
     }                                                                       \
-    static PyObject* register_class(VM* vm, PyObject* mod) {                \
+    static PyObject* register_class(VM* vm, PyObject* mod, Type base=0) {   \
         if(OBJ_NAME(mod) != #mod) {                                         \
             auto msg = fmt("register_class() failed: ", OBJ_NAME(mod), " != ", #mod); \
             throw std::runtime_error(msg);                                  \
         }                                                                   \
-        PyObject* type = vm->new_type_object(mod, #name, vm->tp_object);    \
+        PyObject* type = vm->new_type_object(mod, #name, base);             \
         T::_register(vm, mod, type);                                        \
         type->attr()._try_perfect_rehash();                                 \
         return type;                                                        \