On Tue, Mar 23, 2010 at 5:48 PM, Adam Olsen <[email protected]> wrote:
> a = Decimal('nan')
> a != a
>
> They don't follow the behaviour required for being hashable.
What's this required behaviour? The only rule I'm aware of is that if
a == b then hash(a) == hash(b). That's not violated here.
Note that containment tests check identity before equality, so there's
no problem with putting (float) nans in sets or dicts:
>>> x = float('nan')
>>> s = {x}
>>> x in s
True
Mark
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