[Python-Dev] cmp(x,x) (original) (raw)

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 = somenan 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.