Execute a certain command before closing window in tkinter

Question

I am using tkinter with python.

Is it possible to execute a certain command (eg. print ("hello")) before closing the window, when close button is pressed?

I am using the close button of the desktop environment (along with maximize and minimize) and not any special close button.

Note that I am asking how to execute a certain command before closing, and not how to close the window (which can already be done with the window buttons). So this is not a duplicate of this question

You say it's not a duplicate, but it is. Even though the wording is different ("handle" vs "run a command"), the answer is the same, and it's to use the `protocol` method. — Bryan Oakley, Jun 15 '18 at 13:00
Bryan is correct. Using protocol to redirect the "window close" event to a custom function is the best option. — Mike - SMT, Jun 15 '18 at 13:07

Wololo · Accepted Answer · 2018-06-15T12:49:28.443

4

Depending on what you want to do when the window closes, a possible solution is to wrap your GUI into a class, initialize it in a with statement and do your work in the __exit__() method:

import tkinter


class MainWindow(object):

  def __init__(self):
    print("initiated ..")
    self.root = tkinter.Tk()

  def __enter__(self):
    print("entered ..")
    return self

  def __exit__(self, exc_type, exc_val, exc_tb):
    print("Main Window is closing, call any function you'd like here!")



with MainWindow() as w:
  w.root.mainloop()

print("end of script ..")

edited Jun 15 '18 at 12:49

answered Jun 15 '18 at 12:43

Wololo

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Why is the __enter__(self): required? – Archisman Panigrahi Jun 15 '18 at 16:34
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@ArchismanPanigrahi The `__enter__` method is called when an instance of the class is used in ("entering") a `with` statement. – Wololo Jun 18 '18 at 06:43

score -1 · Answer 2 · answered Jun 15 '18 at 12:16

-1

Here's what I came up with:

import tkinter as tki

def good_bye(*args):
    print('Yo, dawg!')

root_win = tki.Tk()
my_button = tki.Button(root_win, text='I do nothing')
my_button.pack(padx=20, pady=20)
my_button.bind('<Destroy>', good_bye)
root_win.mainloop()

The event is triggered when the widget is destroyed, which happens when you close the main window. Strangely, if you bind the event to the main window, it is triggered twice. Maybe somebody more knowlegeable can shed some light on that.

answered Jun 15 '18 at 12:16

uwain12345

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Why do I need to bind this to the button ? I just need to execute the command when the window is closed. Can I bind this to already existing buttons? – Archisman Panigrahi Jun 15 '18 at 12:21
1

You can bind it to any widget. Like I said, if you bind it to the main window, it'll fire the method twice. – uwain12345 Jun 15 '18 at 12:35
2

FWIW `root_win.bind('', good_bye)` works for me, the function is called only once. Python 3.6.5 from python.org on windows 7 32 bits. – Stop harming Monica Jun 15 '18 at 12:43
1

You don't need to bind to any widgets. just bind to the root window. – Mike - SMT Jun 15 '18 at 13:10
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I tried that, which resulted in the function being called twice. – uwain12345 Jun 15 '18 at 13:22
1

Did you bind to the root window and then also leave your bind on the button? Because that is the only way it would go off twice. – Mike - SMT Jun 15 '18 at 15:22

Execute a certain command before closing window in tkinter

2 Answers2