CODEWITHSUNDEEP
pythonnosepython-import
Xaqq
Xaqq

Reputation: 4386

Python cross-module globale variable

I'm new to Python and I was trying out nose as a unit test framework. I came across a behavior I didn't expect, but maybe this is normal, hence my question.

I have two (very basic) files:

__init__.py:

#!/usr/bin/env python
glob = 0

def setup():
    global glob
    glob = 42
    print "Package setup"

test_mymod.py:

#!/usr/bin/env python
from unittest import TestCase
from . import glob

print "test_mymod.py"

class testMyMod(TestCase):
    def setUp(self):
        print glob

    def test_random(self):
        pass

    def tearDown(self):
        pass

Running nosetest -s gives me following output:

test_mymod.py
Package setup
0

Since the setup() function of the package is invoked before the setUp() function of the test, I expected to see print glob to output 42.

Am I doing something wrong, or is there no way of doing what I want? It seems to me that importing a variable copies its value instead of referencing it, but maybe there is way to do otherwise?

Thank you

Upvotes: 2

Views: 551

Answers (1)

Benjamin Peterson
Benjamin Peterson

Reputation: 20520

When you do from . import glob at the top of your test file, you get a reference to the value of glob in your namespace. This happens before you call setup(). When you call setup() the value of glob is updated in the __init__.py namespace but not test_mymod.py. Instead of importing glob directly, reference it like package.glob. Alternatively, set glob to its correct value at package import time; having unitialized globals that people can import is considered bad practice for exactly this reason.

Upvotes: 2

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