How to unconditionally re-run a python program based on button click?

Question

At the end of my program execution, I want a popup message to appear that has a button which can re-run a program. Obviously, I will have setup a function that the button calls when it is clicked, as such

def restart():
    **python command that makes the whole program restart**

Then I would attach this function to the following button:

B1 = ttk.Button(popup, text='Restart program', width=17, command=lambda: restart())

Is there such a command?

Quick note:I found an answer but it doesn't work, here it is:

os.execl(sys.executable, sys.executable, *sys.argv)

Wrap the 'starting method' (main or similar) in another method that either calls it again or exits, depending on the state of a variable set by the restart popup. — match
– match, Commented Jan 15, 2018 at 16:57
@match Can you please elaborate because I didn't anything you just said :) — Momo 6aye3
– Momo 6aye3, Commented Jan 15, 2018 at 16:59
Can you please explain the problem you want to solve by restarting in details? — Klaus D.
– Klaus D., Commented Jan 15, 2018 at 17:01
I think what @match is saying is to put all of your code in a function: def main(): # all code goes here. Then instead of restart(), the button can just call main(). — Aaron Klein
– Aaron Klein, Commented Jan 15, 2018 at 17:06
Also as an aside, instead of lambda: restart() you can just use restart without parentheses to achieve the same thing. — Aaron Klein
– Aaron Klein, Commented Jan 15, 2018 at 17:08

martineau · Accepted Answer · 2018-01-16 15:04:30Z

I suggest that you use the subprocess module to re-execute the program which was designed to replace the older os.exec...() group of functions.

Here's a runnable (i.e. complete) example of how to use it to restart the script, which was tested on Windows with Python 3.6.4:

import os
import subprocess
import sys
import tkinter as tk
import traceback

class Application(tk.Frame):
    def __init__(self, master=None):
        tk.Frame.__init__(self, master)
        self.pack(fill="none", expand=True)  # Center the button.
        self.create_widgets()

    def create_widgets(self):
        self.restart_btn = tk.Button(self, text='Restart', command=self.restart)
        self.restart_btn.grid()

    def restart(self):
        command = '"{}" "{}" "{}"'.format(
            sys.executable,             # Python interpreter
            __file__,                   # argv[0] - this file
            os.path.basename(__file__), # argv[1] - this file without path
        )
        try:
            subprocess.Popen(command)
        except Exception:
            traceback.print_exc()
            sys.exit('fatal error occurred rerunning script')
        else:
            self.quit()


app = Application()
app.master.title('Restartable application')
app.mainloop()

match · Accepted Answer · 2018-01-17 10:15:22Z

1

This is potentially an over-simple approach, but say your existing program looks something like:

def my_app():
    # Code goes here

if __name__ == "__main__":
    my_app()

Instead wrap it like this:

def my_app():
    print("App is running!")
    # Your app code goes here
    print("App is exiting!")
    # On exit popup a prompt where selecting 'restart' sets restart_on_exit to True
    # Replace input() with a popup as required
    if input("Type y <return> to restart the app! ").lower() == "y":
        return True

if __name__ == "__main__":
    restart_on_exit = True
    while restart_on_exit:
        restart_on_exit = my_app()

That way the code will loop, running my_app over and over again, if the popup sets restart_on_exit to True before the loop repeats.

edited Jan 17, 2018 at 10:15

answered Jan 15, 2018 at 17:05

match

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2 Comments

match Over a year ago

I'm envisaging that my_app is a long running interactive GUI, which will block on the popup to ask about restarting, so a sleep seems unnecessary, but for a short-lived non-interactive method, sure.

Nae Over a year ago

I think this is a better approach than restarting entire script, but the code snippets you use could've been better if they were minimal reproducible examples.

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