Cannot access class __init__ variable from one file to another for code that is split into two diffe-CodePudding

Let's say I have two files: code_for_gui.py and code_for_functions.py,

in my code_for_gui.py I have a class:

Class Main_screen_one():
     def __init__(self, parent, controller):
          Main_screen_one.button_choice = tk.IntVar()

and I have a separate classless function called begin_process() and begin_process does something very trivial like:

import code_for_gui.py

def begin_process():
     print(code_for_gui.Main_screen_one.button_choice.get())

.get() is a tk function to retrieve a value from a user input device (e.g. radio buttons)

When I placed begin_process() in code_for_functions.py I got an Attribute Error stating that button_choice is not an attribute of Main_screen_one, I then tried to change the code to have it as:

def begin_process():
     print(code_for_gui.Main_screen_one().button_choice.get())

including the paranthesis in Main_screen_one(), but then I got another error about not enough parameters being passed as it expected the parent and controller too. So I realize this is wrong, but I'm not entirely sure why?

HOWEVER, when I place begin_process() into code_for_gui.py where Class Main_screen_one() is, I no longer get an error and it works just fine. Can someone please explain why this behavior is happening and where I can potentially read more on this to understand better?

Thank you so much!

CodePudding user response：

The first problem is here (ignoring the obvious syntax error):

Class Main_screen_one():
     def __init__(self, parent, controller):
          Main_screen_one.button_choice = tk.IntVar()

You're setting button_choice on the class rather than the instance of the class. It needs to be this:

self.button_choice = tk.IntVar()

The second problem is where you reference it here:

def begin_process():
     print(code_for_gui.Main_screen_one.button_choice.get())

You should be accessing the attribute on an instance of a class. That means that somewhere you first need to create an instance, and then use the instance to access the variable:

code_for_gui.ms1 = Main_screen_one(...)
...
print(code_for_gui.ms1.button_choice.get())

CodePudding user response：

Have you initialized the class in the code_for_functions.py file? That's why you cannot access the variables defined in the __init__() function. I would have commented but i don't have the rep to do so.