CODEWITHSUNDEEP
python-3.xtkinter
Unsigned_Arduino
Unsigned_Arduino

Reputation: 366

Why does first window need a call to mainloop() while the second window doesn't

I am making a application that needs 2 windows. The first one, I do all the standard stuff like

root = tk.Tk()
...code...
root.mainloop()

But for my second window, I only call

root = tk.Tk()

and it works. If I do

root = tk.Tk()
...code...
root.mainloop()

it still works. Out of pure curiosity, why?

Code:

import tkinter as tk
from tkinter.messagebox import showerror
from time import sleep

class DecompilingChecker(object):
    def __init__(self):
        self.master = tk.Tk()
        self.master.withdraw()
        self.master.title("Test Program: Update")

    def check(self, file, directory):
        self.master.update()
        self.master.deiconify()

class TestProgram(object):
    pass

class GUI(object):
    def __init__(self, master):
        self.master = master
        self.master.title("Test Program")
        tk.Text(self.master).grid(row=0, column=0)
        self.decompilingchecker = DecompilingChecker()
        self.decompilingchecker.check(None, None)

class Bridge(object):
    def __init__(self):
        self.root = tk.Tk()
        GUI(self.root)

    def run(self):
        self.root.mainloop()

if __name__ == "__main__":
    try:
        bridge = Bridge()
        bridge.run()
    except Exception as e:
        showerror("Test Program: ERROR!", "An error has occurred!\n{0}".format(str(e)))
``

Upvotes: 1

Views: 29

Answers (1)

Reblochon Masque
Reblochon Masque

Reputation: 36662

You should not call tk.Tk() more than once. For additional windows, use tk.Toplevel(). Calling update is only necessary in some rare cases, your GUI is most times better off relying on the mainloop for the updates.

import tkinter as tk


class DecompilingChecker(tk.Toplevel):
    def __init__(self, master):
        super().__init__(master)
        self.title("DecompilingChecker Toplevel")

    def check(self):
        print('checking')


class Bridge(tk.Toplevel):
    def __init__(self, master):
        super().__init__(master)
        self.title("Bridge Toplevel")


class GUI(tk.Tk):
    def __init__(self):
        super().__init__()
        self.title("GUI window")
        self.bridge = Bridge(self)
        self.d_checker = DecompilingChecker(self)
        self.d_checker.check()


if __name__ == "__main__":
    GUI().mainloop()

Upvotes: 2

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