0

I'm running a threaded program using tkinter, using different files to separate the program logic:

### File Solution_Name.py ############

import Form_Main as F
from tkinter import *
import tkinter as tk
root = tk.Tk()
app = F.Form_Main(root)
root.mainloop()



### File Form_Main.py ###############

import Program_Logic
import tkinter as tk
from tkinter import *
import threading

class Form_Main:
    def __init__(self, root):

        #Window
        root.title("Main Window")
        root.geometry('1200x600')

        def main_thread():
            Program_Logic.do_tasks()
        threading.Thread(target=main_thread).start()
        
        label_1=tk.Label(root, text = "Initial Label Text").place(x=20, y=20)
        

### File Program_Logic.py ################

import threading

def do_tasks():
    while True:
    
    # Program Logic
    #
    #
    
    label_1.config(text="New Text")

I'm wanting to change the text in label_1 from within the do_tasks() method in Program_Logic.py. The above code doesn't work because label_1 is out of scope. I have tried several things to refer to label_1 from do_tasks():

  • Referring to Form_Main i.e. Form_Main.label_1.config(text="New Text") This fails because it can't see label_1 because it's within the init in Form_Main
  • Putting a function in Form_Main to change label_1. This fails because it will not refer to label_1 unless it has 'self', and I can't find a way of passing the correct 'self' from do_tasks()
  • Putting a function in init within Form_Main. This fails because I can't refer to that function from do_tasks()
  • Make label_1 global, either by using the global keyword, or having it first defined in a separate globals file (which I use for other threading logic). This has the unexpected behavior of label_1 being equal to None immediately after the line label_1=tk.Label(root, text = "Initial Label Text").place(x=20, y=20) so it throws an error when attempting to change the text on a None object.

Is there a way to change the text of label_1 from within the do_tasks() method?

YesThisIsMe
  • 35
  • 5
  • 1
    First of all, `label_1` is `None` due to this [issue](https://stackoverflow.com/questions/1101750/tkinter-attributeerror-nonetype-object-has-no-attribute-attribute-name). After fixing the issue, you can pass `label_1` as an argument to `do_tasks()`. However it is not recommended to update tkinter widget in child thread. – acw1668 Feb 18 '22 at 15:22
  • Many thanks, that solved it. – YesThisIsMe Feb 18 '22 at 15:48

0 Answers0