Question

Since variables names are declared local if there is an assignment to them within a function, and I want to access the module variables from within a function, can I import the module name within the module and then use that to access the module variables ?

Example (file name : server.py):

import server

bar = 5

def foo():
   server.bar = 10

Answer 1

Instead of using the global statement, as suggested in all of the other answers, don’t use module level variables, but a class as a container or else another module just for the globals:

# mg.py

bar = 5

# server.py
import mg

def foo():
    mg.bar = 10

or

class mg:
    bar = 5

def foo():
    mg.bar = 10

This way you don’t need to put global statements everywhere, you can re-use those names, and it’s clear which bar you’re referring to.

Edit: Also, it is possible to import a module inside itself, but you can’t change variables in the main module that way. So this would work:

# selfimport.py
import selfimport

def foo():
    print selfimport.foo

bar = 3

if __name__ == '__main__':
    print selfimport.bar
    foo()

But this wouldn’t:

# selfimport.py
import selfimport

bar = 3

def foo():
    selfimport.bar = 5

if __name__ == '__main__':
    print selfimport.bar
    foo()
    print bar # bar is still 3!

If you’re only using the globals as constants, you wouldn’t need the global statement anyway. You also need to make sure to wrap code you only want to execute in the main module in an if statement as above, or you’ll recurse.