Python close children subprocess

Question

I have a very simple question on killing child subprocesses in scripts written in python 3.

Where,

If I have,

my_process = None

def open_storage():
    my_process = subprocess.Popen("waffles.exe")

def kill_children():
    my_process.kill()

After calling open_storage() , if I call kill_children() , I get

AttributeError: 'NoneType' object has no attribute 'kill'

But if I have,

my_process = None

my_process = subprocess.Popen("waffles.exe")

def kill_children():
    my_process.kill()

Everything works fine.

Can anyone explain this strange behaviour? I need to have open_storage() as a function because it's designed to be triggered by a tkinter button.

Thanks.

Answer 1

You need to use global, otherwise it will use a local variable.

def open_storage():
    global my_process
    my_process = subprocess.Popen("waffles.exe")