I'm curious about the difference between float_subtype_new in floatobject.c complex_subtype_from_c_complex in complexobject.c The former uses type->tp_alloc(type, 0) to create memory for the object while the latter uses PyType_GenericAlloc(type, 0) to create memory for the sub-type (thereby by-passing the sub-type's own memory allocator). It seems like this is a bug. Shouldn't type->tp_alloc(type, 0) also be used in the case of allocating complex subtypes? This is causing problems in NumPy because we have a complex type that is a sub-type of the Python complex scalar. It sometimes uses the complex_new code to generate instances (so that the __new__ interface is the same), but because complex_subtype_from_c_complex is using PyType_GenericAlloc this is causing errors. I can work around this by not calling the __new__ method for the base type but this is not consistent. Thanks for any feedback, P.S. Sorry about the cross-posting to another thread. I must have hit reply instead of compose. Please forgive the noise. -Travis