[Python-3000] super(), class decorators, and PEP 3115 (original) (raw)

Phillip J. Eby pje at telecommunity.com
Tue May 1 03:13:56 CEST 2007

At 05:38 PM 4/30/2007 -0700, Guido van Rossum wrote:

Of course, once the core language adds built-in support for such a feature, it becomes slightly less advanced, and it is reasonable to expect that the special functionality be provided by object or type or some other aspect of the standard class definition machinery (maybe even a default decorator that's always invoked).

Yep. That's precisely it. I'm suggesting that since GF's, enhanced super(), and even potentially @abstractmethod have a use for such a hook, that this would be an appropriate hook to provide in object or type or whatever. Or, have the MAKE_CLASS opcode just do something like:

   ...
   cls = mcls(name, bases, prepared_dict)
   for decorator in cls.__decorators__:
       cls = decorator(cls)
   ...

Heck, I'd settle for:

   ...
   cls = mcls(name, bases, prepared_dict)
   for callback in cls.__decorators__:
       callback(cls)
   ...

As this version would still handle all of my use cases; it just wouldn't be as useful for things like @abstractmethod that really do want to change the metaclass or bases rather than simply be notified of what the class is.

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