[Python-3000] ABC PEP isinstance issue Was: PEP 31XX: A Type Hierarchy for Numbers (and other algebraic entities)

Phillip J. Eby pje at telecommunity.com
Thu Apr 26 02:35:01 CEST 2007

At 04:43 PM 4/25/2007 -0700, Guido van Rossum wrote:
>This is a very good point. Perhaps we can come up with a way to make
>isinstance and issubclass into something like GFs (without requiring
>the whole GF machinery).
>I'll think about it some more.

__special__ methods are how Python currently defines built-in GFs, so 
perhaps __isinstance__ and __issubclass__ slots (and their __r*__ 
counterparts) should suffice.

OTOH, the old PEP 246 (implemented by both PyProtocols and zope.interface) 
just uses __conform__ and __adapt__ and basically works the same way as an 
__isinstance__/__risinstance__ pair...

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