Message406193
> As in most (but not all) cases of dunder methods it
> is looked up in a class, ignoring instance attributes.
That is true, but the starting point in this case is a class so the attribute lookup should be in that class, not its metaclass.
Guido's original code was correct and it became broken in 3.1 in the switch from PyObject_GetAttr(cls, name) to _PyObject_LookupSpecial(cls, &PyId___instancecheck__).
Also, the demonstration code I gave (that matches the documentation) used to work in 3.0 and prior. It broken in 3.1. |
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Date |
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Action |
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2021-11-12 08:07:36 | rhettinger | set | recipients:
+ rhettinger, gvanrossum, serhiy.storchaka |
2021-11-12 08:07:36 | rhettinger | set | messageid: <1636704456.85.0.477943622324.issue45791@roundup.psfhosted.org> |
2021-11-12 08:07:36 | rhettinger | link | issue45791 messages |
2021-11-12 08:07:36 | rhettinger | create | |
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