CODEWITHSUNDEEP
pythonmultithreadingtimertkinter
hddn
hddn

Reputation: 5

tkinter issues in Python

What is best way to get this work? Script hanging at showinfo:

from tkinter import *
from tkinter.messagebox import *
from threading import Timer

def timerDone():
    showinfo('Alert','Alert')

window = Tk()
mainTimer = Timer(3, timerDone)
mainTimer.start()

window.mainloop()

I use Python 3. Is there is a way to get it work without Queue or additional imports?

I don't use "after" method because Timer can be stoped or changed - I have a lot of timers with dynamically changeable interval and this is very inconvenient.

Upvotes: 0

Views: 137

Answers (1)

ebarr
ebarr

Reputation: 7842

As discussed here: python tkinter with threading causing crash

Tkinter is not thread safe; you cannot access Tkinter widgets from anywhere but the main thread.

You should remove the Timer instantiation. Tk has its own tool for scheduling events called the after method. 

from tkinter import *
from tkinter.messagebox import *

def timerDone(window):
    showinfo('Alert','Alert')
    window.destroy()

window = Tk()
window.after(3000,lambda:timerDone(window))
window.mainloop()

This is the same script implemented using after. I also added a window.destroy() call to break the mainloop.

There are a couple of solutions to your problem. The simplest is to use the after_cancel method to stop a callback from being executed. Its worth also noting that after events are bound to a widget, so if the widget that owns the after is destroyed, the callback will never be executed.

Upvotes: 2

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