Python programming, object-oriented programming in different files with classes?

Hey,

I am currently learning Python and have started programming a chatbot.
Now I want to start getting used to programming in different files using object-oriented programming, or rather, learn how to do that first.
My idea in my code is to create a class WindowTemplate and define it as a blueprint without any predefined values.
I can actually do that, but I'm having problems accessing it from another class in another file and passing values ​​like size or title.
I would be happy if someone with some experience could take a look at this and at least point me in the right direction. 🙂
Many thanks!

main.py

The error message is this:

Traceback (most recent call last):

line 17, in <module>

app = Main()

^^^^^^

line 9, in __init__

self.main_window.set_size("1680", "900")

line 10, in set_size

self.window_size.geometry(f"{width}x{height}")

^^^^^^^^^^^^^^^^^^^^^^^^^

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

 import view import customtkinter as ctk class Main(ctk.CTk): def __init__(self): super().__init__() self.main_window = view.WindowTemplate() self.main_window.set_size("1680", "900") self.main_window.set_title("YourTerminal") def my_mainloop(self): self.mainloop() if __name__ == "__main__": app = Main() app.my_mainloop()

view.py

 import customtkinter as ctk class WindowTemplate: def __init__(self, window_size=None, window_title=None): self.window_size = window_size self.window_title = window_title def set_size(self, width, height): self.window_size.geometry(f"{width}x{height}") def set_title(self, title): self.window_title.title(title)