How should one access nonlocal variables in closures in python 2.x?

Inner functions can read nonlocal variables in 2.x, just not rebind them. This is annoying, but you can work around it. Just create a dictionary, and store your data as elements therein. Inner functions are not prohibited from mutating the objects that nonlocal variables refer to.

def outer():
    d = {'y' : 0}
    def inner():
        d['y'] += 1
        return d['y']
    return inner

f = outer()
print(f(), f(), f()) #prints 1 2 3

Or using nonlocal class:

def outer():
    class context:
        y = 0
    def inner():
        context.y += 1
        return context.y
    return inner

It works because you can modify nonlocal variables. But you cannot do assignment to nonlocal variables.