[Python-Dev] Extending types in C - help needed

[Martin v. Loewis]

> Wouldn't it suffice to check for tp_dict != NULL (after the call
> to PyType_Ready of course)?

No, see below (although I must admit that I wrote "Right" here first
:-)

> Hm. What does Py_TPFLAGS_HAVE_CLASS mean exactly?

According to the documentation, it means that the underlying
TypeObject structure has the necessary fields in its C declaration.

> Or, better, since TPFLAGS_DEFAULT contains TPFLAGS_HAVE_CLASS,
> what does it mean when Py_TPFLAGS_HAVE_CLASS is NOT in tp_flags?

It means you have been loading a module from an earlier Python
version, which had a different setting for TPFLAGS_DEFAULTS, and a
shorter definition of the TypeObject.

If you try to access tp_dict in such an object, you are accessing
random memory. This may immediately crash, or only crash when you pass
the pointer you got to the dictionary functions.

Regards,
Martin