[Python-3000] Metaclasses in Py3K (original) (raw)

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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