[Python-3000] Metaclasses in Py3K

Talin talin at acm.org
Sat Dec 16 21:35:07 CET 2006

Josiah Carlson wrote:

>> 2) What should the interface on the metaclass look like.
>> The general idea is to have the metaclass create a mapping object which 
>> is used as the 'locals' dictionary for the suite following the class 
>> statement. There would be some special-named function of the metaclass, 
>> such as '__metadict__', which would construct a new mapping object. I 
>> haven't seen many alternative proposals to this.
> Proposal: don't make it a callable on the metaclass.  It forces
> metaclasses into being classes, which I think is overly restrictive, or
> it forces people to do things like...
>     def mymeta(...):
>         ...
>     mymeta.__metadict__ = mydict

I suppose you could make the new syntax require a callable that returns 
a tuple of a dict and a finishing function, i.e.:

    def mymeta( ... ):
       def finish( dict ):

       return finish, {}

    class Foo( metaclass=mymeta ):

-- Talin

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