[Python-Dev] cmp(x,x)

Tim Peters tim.one at comcast.net
Tue May 18 14:37:31 EDT 2004


> >>> cmp(x,x)           #   x.__cmp__() is NOT called
> 0

[Gustavo Niemeyer]
> This is odd. We'll have problems trying to implemnt a NaN
> following the convention of being not-equal to itself,
> for example.

That's what rich comparisons are for.  There's no problem getting

>>> x = some_nan
>>> x = x
False
>>>

in Python 2.4 (the result of that is *currently* a platform-dependent
crapshoot, though).

cmp(x, y) doesn't make sense for objects having only a partial ordering, so
I don't care cmp() does with a NaN.





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