On 20 Jul, 2013, at 1:47, Ethan Furman <et...@stoneleaf.us> wrote:
> While working on issue #18508 I stumbled across this:
>
> Traceback (most recent call last):
> ...
> File "/usr/local/lib/python3.4/enum.py", line 417, in __new__
> if value in cls._value2member_map:
> TypeError: unhashable type: 'list'
>
> I'll wrap it in a try-except block, but I must admit I was surprised the
> answer wasn't False. After all, if the input is unhashable then obviously
> it's not in the dict; furthermore, if I were to compare the number 5 with a
> set() I would get False, not a TypeMismatch error, and dict keys are
> basically done by equality, the hash is just (?) a speed-up.
Not quite, there are some objects that compare equal without both of them being
hashable:
>>> frozenset([1,2]) == set([1,2])
True
>>> dct = { frozenset([1,2]): 1 }
>>> frozenset([1,2]) in dct
True
>>> set([1,2]) in dct
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'set'
It would be strange if the last test would return False instead of raising an
error.
Ronald
>
> --
> ~Ethan~
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