[Python-3000] Revised PEP 3119 (Abstract Base Classes)

Paul Moore p.f.moore at gmail.com
Mon May 14 12:56:47 CEST 2007

On 12/05/07, Guido van Rossum <guido at python.org> wrote:
> Here's a new version of the ABC PEP. A lot has changed; a lot remains.
> I can't give a detailed overview of all the changes, and a diff would
> show too many spurious changes, but some of the highlights are:

As a general comment, I like the direction this has moved in. In
particular, I like the fact that ABCs can be registered after the fact
(as Talin describes it, "post-hoc classification".

> ABCs vs. Duck Typing

This remains my key concern. The PEP nicely addresses the issue as far
as core Python is concerned, but I'd be happier with some style
recommendations for 3rd party frameworks clarifying that they should
also avoid taking the "stick" approach. OTOH, we've had interface
implementations, and heavy users of them (e.g. zope.interface and
Twisted) for ages now, and the world hasn't ended, so I guess there's
no reason to assume that people won't use ABCs sensibly, too.

Overall, then, I'm moving towards a +1 (or at least a +0.5...)


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