Modify the function variables from inner function in python

Question

It\'s ok to get and print the outer function variable a

def outer():
    a = 1
    def inner():
        print a

It\'s also ok

Answer 1

A generally cleaner way to do this would be:

def outer():
    a = 1
    def inner(b):
        b += 1
        return b
    a = inner(a)

Python allows a lot, but non-local variables can be generally considered as "dirty" (without going into details here).

Answer 2

In Python 3 you can do this with the nonlocal keyword. Do nonlocal a at the beginning of inner to mark a as nonlocal.

In Python 2 it is not possible.

Answer 3

Workaround for Python 2:

def outer():
    a = [1]
    def inner():
        a[0] += 1
        print a[0]