[Python-Dev] Rich comparison confusion

Moshe Zadka moshez@zadka.site.co.il
Thu, 18 Jan 2001 02:08:06 +0200 (IST)


On Wed, 17 Jan 2001 09:17:39 -0600 (CST), Skip Montanaro <skip@mojam.com> wrote:

> I'm a bit confused about Guido's rich comparison stuff.  In the description
> he states that __le__ and __ge__ are inverses as are __lt__ and __gt__.

I think that you're confused between two meanings of inverses.

You think:
op is an inverse of op' if for every a,b  (a op b) = not (a op' b)

Guido meant (and I hope, implemented):
op is an inverse of op' if for every a,b  (a op b) =  (b op' a)

And a<b iff b>a 
a<=b iff b>=a

Sounds sane.

Unless I'm the one confused....
-- 
Moshe Zadka <sig@zadka.site.co.il>
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