[Python-3000] PEP for Metaclasses in Python 3000

[Steven Bethard]

On 3/12/07, Phillip J. Eby <pje at telecommunity.com> wrote:
> At 09:32 PM 3/12/2007 -0600, Steven Bethard wrote:
> >On 3/12/07, Steven Bethard <steven.bethard at gmail.com> wrote:
> > > the signature of the method called will be::
> > >     __prepare__(name, args, kwargs)
> > > not
> > >     __prepare__(name, *args, **kwargs)
> > > right?
> >
> >On 3/12/07, Guido van Rossum <guido at python.org> wrote:
> > > I'm not sure anyone has thought much about it yet. I wonder
> > > if the call shouldn't be made like this:
> > >
> > > __prepare__(name, bases, **kwargs)
> > >
> > > so that if you only expect certain specific keyword args you can
> > > define it like this:
> > >
> > > def __prepare__(name, base, metaclass=X): ...
> >
> >Yeah, seems like **kwargs would be more useful in practice.
>
> Really?  Why?  I can more easily see circumstances where you'd want to
> restrict the arguments. In the cases I have where I'd switch from a class
> decorator to a class keyword, I have a small set of decorators and would
> have an equally small set of keywords.

Maybe I'm misunderstanding but isn't this a reason that you'd *want*
the ``**kwargs`` signature?  With the plain ``kwargs`` signature from
the PEP you'd have to do something like::

    def __prepare__(name, args, kwargs):
        required = kwargs.pop('required', None)
        if required is not None:
            ...

STeVe
-- 
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