Imported a Python module; why does a reassigning a member in it also affect an import elsewhere?

Question

I am seeing Python behavior that I don't understand. Consider this layout:

project
|   main.py
|   test1.py
|   test2.py
|   config.py

main.py:

import config as conf
import test1
import test2

print(conf.test_var)
test1.test1()
print(conf.test_var)
test2.test2()

test1.py:

import config as conf

def test1():
    conf.test_var = 'test1'

test2.py:

import config as conf

def test2():
    print(conf.test_var)

config.py:

test_var = 'initial_value'

so, python main.py produce:

initial_value
test1
test1

I am confused by the last line. I thought that it would print initial_value again because I'm importing config.py in test2.py again, and I thought that changes that I've made in the previous step would be overwritten. Am I misunderstanding something?

Answer 1

test2.py

import config as conf

def test2():
    print(id(conf.test_var))
    print(conf.test_var)

test1.py

import config as conf

def test1():
    conf.test_var = 'test1'
    print(id(conf.test_var))

Change code like this.

And run main.py

initial_value
140007892404912
test1
140007892404912
test1

So, you can see that in both cases you are changing value of the same variable. See these id's are same.

Answer 2

Python caches imported modules. The second import call doesn't reload the file.