scope.py

"""
There is an unfortunate thing about Python scoping. You can't easily access the variables
of a calling function (as you can do in Scheme) so if you want to use those variables you
need to jump thru silly hoops. See
https://stackoverflow.com/questions/15608987/access-variables-of-caller-function-in-python

The nice thing about using a caller's variables is that it provides a nice way to do closures.
Variable access in closures will work OK as long as you are not ASSIGNING the variable. In
this case, we assign indices of "scope" but we never assign scope itself -- if we did, Python
would conclude that scope belongs to stuff, not to make_thing. Annoying.
"""

def make_thing():
    internal_vbl = 0
    scope = locals()

    def stuff():
        scope['internal_vbl'] += 1
        return scope['internal_vbl']

    return stuff

f = make_thing()
for _ in range(5):
    print f()