Mark Dickinson <[email protected]> added the comment:
There's a second issue to consider here, which is that Python uses
equality as specified by the == operator as the basic equivalence relation
for set and dict membership tests. So as a general rule, an equality test
between two objects of the same type shouldn't be raising exceptions. If
== raised for comparisons with nans then it would make it awkward to put
nans into a set.
Hmm. But now I notice that you can't put Decimal nans into sets anyway:
you get a 'TypeError: Cannot hash a NaN value'. I'm not sure of the
rationale for this.
One might also question whether Decimal("NaN") < 9 should really be
raising InvalidOperation, or whether (as an operation that doesn't return
a Decimal instance and is in some sense outside the scope of the standard-
--similar to int(Decimal('nan')) and hash(Decimal('nan'))) it should be
raising some general Python exception instead.
I'm closing this as invalid: the behaviour isn't a bug, at least in the
sense that the code is working as designed. I think there may well be a
useful discussion here, but the bugtracker isn't the right place to have
it: could we move it to python-dev instead?
----------
resolution: -> invalid
status: open -> closed
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Python tracker <[email protected]>
<http://bugs.python.org/issue7279>
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