Closures

[Mark McEahern]

On Thu, 2004-04-29 at 17:17, Michael Sparks wrote:
> On Thu, 29 Apr 2004, Gustavo Niemeyer wrote:
> 
> > class Closure:
> >     def __init__(self):
> >         self.__dict__ = sys._getframe().f_back.f_locals
> 
> Out of interest how portable is this? Strikes me as extremely useful
> class to have lying around :) The only thing that makes me wonder is the
> access to _getframe...

There are more straightforward ways to get at locals--here's a modified
version that uses doctest to demonstrate/prove what the code does.  Is
the value of Closure--beyond just plain old nested scopes--that you
don't have to pass counter into getFunc()?

#!/usr/bin/env python

import doctest
import unittest

class Closure:
    def __init__(self, **kwargs):
        self.__dict__.update(kwargs)

def getFunc():
    """
    >>> c = getFunc()
    >>> c()
    1
    >>> c()
    2
    >>> c()
    3
    """
    counter = 0
    c = Closure(**locals())
    def count():
        c.counter += 1
        print c.counter
    return count

def test_suite():
    return doctest.DocTestSuite()

if __name__ == '__main__':
    unittest.main(defaultTest='test_suite')