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tkinter event loop

tkinter gives you the event loop for free

In order to process events efficiently, GUIs employ an event loop. Event
loops watch and wait for events, calling a piece of code each time an
event occurs. If you think about the current TVN Game Show program,
it already has a very basic event loop that waits for the host to press 1, 2,
or 0. The program then calls some code before waiting again for another
key-press event from the host. To implement this in code, you used a while
loop:

while choice != '0':
if choice == '1':
number_asked = number_asked + 1
number_correct = number_correct + 1
Click on the close
box to terminate
this application.
In tkinker, you don’t need to write a while loop like you did for your
non-GUI program. In tkinter, call the mainloop() method instead:
Import everything from
the tkinter module.

from tkinter import *
Give the Create a tkinter application These five lines of
window called “app”.
window a app = Tk() Python/tkinter code
name. app.title("Your tkinter application") produce this GUI.
app.geometry('450x100+200+100')
Provide window app.mainloop()
coordinates and
size values. Start the tkinter event loop.

To add a button to your application, use code like this, being sure to put
these two lines of code before the call to mainloop():

The button’s been
b1 = Button(app, text = "Click me!", width = 10)
added to the GUI.
b1.pack()

Add a button to The pack() method links
the window and give the newly created button
it some text and a to the existing window.
width value.

234 Chapter 7