Frosty Z Frosty Z - 3 months ago 9
Python Question

Python: accessing "module scope" vars

I'm currently learning Python, and I have to work on a Python 2.7 project.

Accessing "module scope" variables in functions of the module itself is a bit confusing for me, and I didn't succeed in finding a satisfying way.

My attempts so far:

Way 1:

my_module.py

my_global_var = None

def my_func():
global my_global_var
my_global_var = 'something_else'


Here I think that confusing local and "module scope" vars may be quite easy.

Way 2:

my_module.py

import my_module

my_global_var = None

def my_func():
my_module.my_global_var = 'something_else'


Here, the name of "my_module" could not be as easily changed as "way 1" when necessary. Plus, importing a module into itself sounds quite weird.

What would you recommend? Or would you suggest something else? Thanks.

Answer

You probably want to read up on Python's namespaces. Way 1 is correct but generally unnecessary, never use 2. An easier approach is to just use a dict (or class or some other object):

my_globals = {'var': None}

def my_func():
    my_globals['var'] = 'something else'

Assignments always go into the innermost scope and the innermost scope is always searched first, thus the need for the global keyword. In this case you aren't assigning to a name, so it's unnecessary.