[Python-Dev] Re: cmp(x,x) (original) (raw)
Casey Duncan casey at zope.com
Fri May 21 15:37:08 EDT 2004
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On Fri, 21 May 2004 15:21:09 -0400 "Tim Peters" <tim.one at comcast.net> wrote:
[Armin Rigo] [..] NaN comparison is a red herring not only because Python doesn't have a sane story in any area involving NaNs, but also because the 32 possible 754 comparison predicates can't be mapped onto 6 operator symbols. Note that in C99, the infix C relational operators raise an exception (754's "invalid operation") when applied to a NaN, and C99 adds a pile of new macros for non-exceptional NaN comparison (my favorite is the fetchingly named"islessgreater(x, y)" -- which "is similar to (x) < (y) || (x) > (y); however, islessgreater(x,y) does not raise the invalid exception when x and y are unordered (nor does it evaluate x and y twice)").
Finally, a use for <>. Barry will be so happy ;^)
-Casey
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