[Python-Dev] metaclass insanity (original) (raw)

Walter D�rwald walter@livinglogic.de
Tue, 05 Nov 2002 11:21:14 +0100

Martin v. Loewis wrote:

Guido van Rossum <guido@python.org> writes:

In the case of nested classes, a possible solution might be for X.Y.name to be "X.Y" rather than plain "Y". Then a simple change to pickle (or to getattr :-) could allow the correct unpickling. I'd rather expect that X.Y.module is "Foo.X".

Even better would to have "X.Y.outerclass is X", i.e. outerclass as a (weak) reference to the class in which X.Y was defined. What I came up with is this:

class nestedtype(type): def new(cls, name, bases, dict): dict["outerclass"] = None res = type.new(cls, name, bases, dict) for (key, value) in dict.items(): if isinstance(value, type): value.outerclass = res return res

def __fullname__(cls):
   name = cls.__name__
   while 1:
      cls = cls.__outerclass__
      if cls is None:
         return name
      name = cls.__name__ + "." + name

def __repr__(cls):
   return "<class %s/%s at 0x%x>" % \
      (cls.__module__, cls.__fullname__(), id(cls))

Bye, Walter D�rwald