Hi,
I'm trying to understand the purpose of the check in tp_new_wrapper() of
typeobject.c that results in the "is not safe" exception.
I have the following class hierarchy...
B -> A -> object
...where B and A are implemented in C. Class A has an implementation of
tp_new which does a few context-specific checks before calling
PyBaseObject_Type.tp_new() directly to actually create the object. This
works fine.
However I want to allow class B to be used with a Python mixin. A's
tp_new() then has to do something similar to super().__new__(). I have
tried to implement this by locating the type object after A in B's MRO,
getting it's '__new__' attribute and calling it (using PyObject_Call())
with B passed as the only argument. However I then get the "is not safe"
exception, specifically...
TypeError: object.__new__(B) is not safe, use B.__new__()
I take the same approach for __init__() and that works fine.
If I comment out the check in tp_new_wrapper() then everything works
fine.
So, am I doing something unsafe? If so, what?
Or, is the check at fault in not allowing the case of a C extension type
with its own tp_new?
Thanks,
Phil
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