How to define variables in case they their values change through a thread?

September 23, 2024

I have main.py which looks like the following:

...
val1, val2 = None, None
...
thread1 = threading.Thread(func1, )               
thread1.start()
while condition:
    continue
else:
    thread1.join()

#check the values of val1 and val2 after the thread had changed them
if val1!= None and val2!= None:
    do_something()

on the other hand func1 is defined in main.py script as follows:

...
def func1():
    global val1, val2
    val1, val2 = process_something_and_return_values()

My question will defining func1() as I do will guarantee to find val1 and val2 changed and not assigned to None?

if not how to go about this kind of setting to change values of variables through a thread

PS: using Python 2.7

UPDATE: Python doesn’t have the ability to change variables across modules. Therefore I want to check if the code is correct if it is in the same module?

>Solution :

Explicitly define val1 and val2 as globals in function_helpers.py:

val1, val2 = None

... # etc.

Then in main.py import just the module function_helpers and then refer to variables and functions within that module. In this way both modules are sharing the same val1 and val2 instances:

import function_helpers
...
function_helpers.val1, function_helpers.val2 = None, None
...
thread1 = threading.Thread(target=function_helpers.func1)               
thread1.start()
while condition:
    continue
else:
    thread1.join()

#check the values of val1 and val2 after the thread had changed them
if function_helpers.val1!= None and function_helpers.val2!= None:
    do_something()