[Cython] cdef class tp_new should call PyBaseObject_Type.tp_new?

Stefan Behnel stefan_ml at behnel.de
Fri Jan 10 10:52:44 CET 2014

Stefan Behnel, 10.01.2014 10:11:
> Simon Jagoe, 09.01.2014 14:04:
>>> Looking at the code in Py3, ISTM that it would be sufficient to do this iff
>>>         (t->tp_flags & Py_TPFLAGS_IS_ABSTRACT) != 0
>>> which should be rare enough.
>>> Obviously requires some user side testing to see if it breaks any other code...
>> Thanks for looking at this. I am wondering if there is a reason why the
>> tp_alloc can't be replaced with the PyBaseObject_Type->tp_new directly?
> I don't know. At least, it's some unnecessary overhead in almost all cases.
> Not sure if that matters, there's enough costly stuff happening at this
> point anyway.
> ISTM that we'd also have to fix the issue that Nils Bruin found, otherwise
> we'd risk even more trouble on user side.
> http://thread.gmane.org/gmane.comp.python.cython.user/10267
>> My understanding is that initially, object's tp_new essentially just
>> called tp_alloc as Cython does now.  Later the abc feature was added
>> with the abstract check happening in object's tp_new, while not changing
>> previous (non-abstract class) behavior.  If Cython were to use this
>> instead of tp_alloc, it would be forward-compatible with future changes
>> to object.
> Agreed.

Let's see what Jenkins has to say about it.



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