Annoying behaviour of the != operator

[George Sakkis]

"Jordan Rastrick" wrote:

> I'd suggest the only nessecary change is, if objects a,b both define
> __eq__ and not __ne__, then a != b should return not (a == b)
>
> If a class defines __ne__ but not __eq__, well that seems pretty
> perverse to me. I don't especially care one way or another how thats
> resolved to be honest.
>
> The ordering comparisons (__lt__, __ge__ etc) are fine as they are I'd
> say, since they only come up in the rare cases where __cmp__ isn't
> sufficient.
>
> I'll wait for a bit more discussion on here before starting a PEP - as
> I've said I'm only a beginner, and a more experience Pyonista may yet
> give a perfectly good argument in favour of the current behaviour.
>

I've been bitten by this particular wart more than once, so I wrote a
metaclass for automating the addition of the missing rich comparisons
with the expected semantics: == and != are complementary, and given
either of them and one of <, >, <=, >=, the other three are defined.
You can check it out at
http://rafb.net/paste/results/ymLfVo81.html. Corrections and comments
are welcome.

Regards,
George