[Python-Dev] Why doesn't functools.total_ordering use the existing ordering methods? (original) (raw)

Raymond Hettinger raymond.hettinger at gmail.com
Mon Apr 25 21:13:54 CEST 2011

On Apr 25, 2011, at 11:43 AM, cool-RR wrote:

Today I was trying to use totalordering for the first time. I was expecting that in order to implement e.g. x > y it would do not x < y and not x == y, assuming that _lt_ and _eq_ are defined.

This was fixed. The current code has:

convert = {
    '__lt__': [('__gt__', lambda self, other: not (self < other or self == other)),
               ('__le__', lambda self, other: self < other or self == other),
               ('__ge__', lambda self, other: not self < other)],
    '__le__': [('__ge__', lambda self, other: not self <= other or self == other),
               ('__lt__', lambda self, other: self <= other and not self == other),
               ('__gt__', lambda self, other: not self <= other)],
    '__gt__': [('__lt__', lambda self, other: not (self > other or self == other)),
               ('__ge__', lambda self, other: self > other or self == other),
               ('__le__', lambda self, other: not self > other)],
    '__ge__': [('__le__', lambda self, other: (not self >= other) or self == other),
               ('__gt__', lambda self, other: self >= other and not self == other),
               ('__lt__', lambda self, other: not self >= other)]
}

Why not have totalordering work in the way I suggested?

To avoid needless posts, you should use the tracker.

Raymond

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