tk messagebox import confusion

Question

I'm just beginning to learn tkinter at the moment, and when importing messagebox I found that I must not really understand import statements.

The thing that confuses me is that:

import tkinter as tk

def text_box():
    if tk.messagebox.askokcancel("Quit", "Never Mind"):
        root.destroy()

root = tk.Tk()
button = tk.Button(root, text="Press the button", command=text_box)
button.pack()
root.mainloop()

compiles fine, but pressing the button gives the error 'module' object has no attribute 'messagebox', while the code:

import tkinter as tk
from tkinter import messagebox

...
    if messagebox.askokcancel("Quit", "Never Mind"):
...

...works without a hitch.

I get a similar error if I import with from tkinter import *.

The help for tkinter shows messagebox in the list of PACKAGE CONTENTS, but I just can't load it in the normal way.

So my question is, why...and what is it about importing that I don't understand?

Just thought I should mention—the code only works in Python 3, and in Python 2.x messagebox is called tkMessageBox and is not defined in tkinter.

Answer 1

tkinter.messagebox is a module, not a class.

As it isn't imported in tkinter.__init__.py, you explicitly have to import it before you can use it.

import tkinter
tkinter.messagebox  # would raise an ImportError
from tkinter import messagebox
tkinter.messagebox  # now it's available eiter as `messagebox` or `tkinter.messagebox`