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Boilerplate in rich comparison methods

Paul Rubin http
Sat Jan 13 02:28:06 EST 2007 
Steven D'Aprano <steve at REMOVE.THIS.cybersource.com.au> writes:
> class Parrot:
>     def __eq__(self, other):
>         return self.plumage() == other.plumage()
>     def __ne__(self, other):
>         return self.plumage() != other.plumage()
>     def __lt__(self, other):
>         return self.plumage() < other.plumage()
>     def __gt__(self, other):
>         return self.plumage() > other.plumage()
>     def __le__(self, other):
>         return self.plumage() <= other.plumage()
>     def __ge__(self, other):
>         return self.plumage() >= other.plumage()

If it's that uniform I think you can just use __cmp__:

 class Parrot:
    def __cmp__(self, other):
       return cmp(self.plumage(), other.plumage())

Did I miss something?  The idea of rich comparison is that the
different relations aren't so similar to each other, e.g. some kind of
partial ordering.

> If the comparison requires a lot of work, I'll do something like this:
> 
> class Aardvark:
>     def __le__(self, other):
>         return lots_of_work(self, other)
>     def __gt__(self, other):
>         return not self <= other
>     # etc.
> 
> But I can't help feeling that there is a better way. What do others do?

Same as above.
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