Nested scopes and lexical closures

[Paul Rubin]

I see that Python 2.1.1 lets you import nested scopes from the future.
However, I couldn't easily tell from the documentation whether that
means you can make lexical closures:

  def counter():
    value = 0
    def incr():
      value += 1
      return value
    return incr

This turns out to throw a runtime exception:

    >>> a=counter()
    >>> a()
    Traceback (most recent call last):
      File "<stdin>", line 1, in ?
      File "/usr/tmp/python-170562C", line 6, in incr
    UnboundLocalError: local variable 'value' referenced before assignment

Of course that's disappointing and I'm wondering if there's some
intention to fix it in the future.  Meanwhile I think the
documentation of nested scopes should be updated to make it clear that
closures don't work.