[Python-Dev] metaclass insanity

[Just van Rossum]

Alex Martelli wrote:

> class Outer:
>     [snip snip]
>     def __iter__(self):
>         class Inner:
>             def __init__(self, outer):
>                 self.outer = outer
>             def __iter__(self):
>                  return self
>             def next(self):
>                  if self.outer.isAtEnd():
>                     raise StopIteration
>                  else:
>                     result = self.outer.currentState()
>                     self.outer.advanceState()
>                     return result
>         return Inner(self)

While I'm sure this was just a theoretical example, _this_ specific case is much
easier written as a generator (and I _love_ the idiom of making the __iter__
method a generator, I think it's underused...).

class Outer:
    [snip snip]
    def __iter__(self):
        while not self.isAtEnd():
            result = self.outer.currentState()
            self.outer.advanceState()
            yield result

Just