Serhiy Storchaka <[email protected]> added the comment:
Setting __hash__ to None doesn't do what you think. It doesn't prevent __hash__
from being called by hash(), instead it produces a TypeError.
>>> class A: __hash__ = None
...
>>> hash(A())
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'A'
Actually the effect of special casing __hash__ is not raising a TypeError, but
raising a TypeError with better error message. A TypeError was already raised
before if set __hash__ to a non-callable. In 2.7:
>>> class A: __hash__ = None
...
>>> hash(A())
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: 'NoneType' object is not callable
If you want to prevent an inherited __init__ from being called by types's
__call__, you can define an __init__ with an empty body.
def __init__(self, *args, **kwargs):
pass
----------
nosy: +serhiy.storchaka
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<https://bugs.python.org/issue34314>
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