Alternative to using global parameters in Tkinter

Question

Is there a better way to implement a code like this without using global parameters? I was taught that global parameters generally isnt a good thing in python. What do you guys think? do you think global parameters are okay?

This is the code

import Tkinter as tk


def main():    
    global root

    root = tk.Tk()   # parent window


    message = tk.Label(root, text = "Hello World") 
    message.pack() 

    buttton = tk.Button(root, text="exit", command = buttonPushed) 
    button.pack()

    tk.mainloop()  


def buttonPushed():
    global root
    root.destroy()

main()

on the line where I create the button, if instead I write something like this;

buttton = tk.Button(root, text="exit", command = buttonPushed(root)) 
button.pack()


def buttonPushed(root):
    root.destroy()    

the program will not work as required.

Any suggestions?

Answer 1

Your buttonPushed function is unnecessary because you can assign the button's command parameter to the root.destroy function directly:

button = tk.Button(root, text="exit", command=root.destroy) 

Thus, your code becomes just this¹:

import Tkinter as tk

def main():    

    root = tk.Tk()

    message = tk.Label(root, text="Hello World") 
    message.pack() 

    button = tk.Button(root, text="exit", command=root.destroy) 
    button.pack()

    tk.mainloop()  

main()

_{¹Note: I also removed the global root line at the top of main because it is unnecessary.}

Answer 2

You can write it using classes but as iCodez says, that button is kind of unnecessary right now.

import Tkinter as tk

class interface(tk.Frame):
    def __init__(self, root):
        tk.Frame.__init__(self, root)

        self.root = root
        message = tk.Label(self.root, text = "Hello World") 
        button = tk.Button(self.root, text="exit", command = self.buttonPushed) 

        message.pack()
        button.pack()

    def buttonPushed(self):
        self.root.destroy()

root = tk.Tk()
inter = interface(root)
root.mainloop()