[Python-Dev] Mixing float and Decimal -- thread reboot

[Mark Dickinson]

On Tue, Mar 23, 2010 at 5:48 PM, Adam Olsen <rhamph at gmail.com> 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