[Python-3000] Breakthrough in thinking about ABCs (PEPs 3119 and 3141)

[Jim Jewett]

On 4/30/07, Guido van Rossum <guido at python.org> wrote:

> The idea of overloading isinstance and issubclass is running into some
> resistance. I still like it, but if there is overwhelming discomfort,
> we can change it so that instead of writing isinstance(x, C) or
> issubclass(D, C) (where C overloads these operations), you'd have to
> write something like C.hasinstance(x) or C.hassubclass(D), where
> hasinstance and hassubclass are defined by some ABC metaclass. I'd
> still like to have the spec for hasinstance and hassubclass in the
> core language, so that different 3rd party frameworks don't need to
> invent different ways of spelling this inquiry.

Would it help to get away from class/instance entirely, and call them
something like isexample?  (Though class vs instance gets harder then.
 areexamples?)

(And yes, I think it would, but no, I don't yet have the code written
out to explain.)

-jJ