Result of ``a is b''

[Andrew Koenig]

"Carl Banks" <imbosol at aerojockey.invalid> wrote in message
news:2eu6c.25407$P45.19517 at fe1.columbus.rr.com...

> > I don't think the argument that one can redefine __eq__
> > to be something other than an equivalence relation is a
> > particularly strong argument. I would call that a bug,
> > even if it is a deliberate bug. If "==" doesn't do
> > equality, then it is an exceedingly bad piece of design.

> You know, it's not hard to imagine some abstract mathematical superset
> of the normal orthogonal math we use everyday, wherein certain numbers
> (or sets or whatever) are not equal to themselves.  In which case it
> would be entirely appropriate for __eq__ to return False if called
> with the same object.  Of course, that's not really the typical case.

I'm pretty sure that IEEE floating point requires NaN to be defined in such
a way that if x is NaN, then x == x must yield False.