[Python-3000] Generic function PEP won't make it in time

Calvin Spealman ironfroggy at gmail.com
Wed Apr 25 19:37:47 CEST 2007

On 4/25/07, Emin.shopper Martinian.shopper <emin.shopper at gmail.com> wrote:
> I disagree. I think that B&D-ish enforcement of ABCs is the most important
> feature of an ABC (with the option of being able to turn off enforcement on
> a per-class basis).
> Imagine you have a program that takes a long time to run. If you use
> duck-typing or similar ideas you may watch the program run for hours or days
> and then raise an AttributeError or NotImplemented error because a derived
> class didn't implement a required method. With B&D-ish enforcement of ABCs,
> you can automatically catch such problems as soon as the program starts.
> This is a problem that I see no other good solution to. For long running
> programs, unit-tests will also take a long time to run so the argument that
> your unit-tests should catch such errors is no longer valid. Also, while
> pylint and pychecker are great tools that could be used to catch such
> errors, they must be run manually by the programmer and generally take a
> long time to run (at least longer than the ABC implementation I! have).
> To reiterate, while I think the documentation and reflection benefits of
> ABCs are nice, I don't think they are nearly as essential as enforcement.
> For most of the use cases I've seen, you could just as easily read the
> documentation or the source code or try a simple example to determine how to
> implement an iterable or hashable that will play nice with other classes. In
> contrast, ABC enforcement provides the real benefit of catching errors
> before many hours of program runtime are wasted. Consequently, I'm +1 on B&D
> in this case.
> -Emin Martinian

It sounds like you just need better unit tests.

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