Python GUI wrapper for a long operation

[Jeff Epler]

To interleave calculation and GUI activity in the same thread, simply
call the "update_idletasks" or "update" method on any Tk widget at
intervals.

update_idletasks() will do things like repaint windows that have been
uncovered or resized, or when the information displayed on a widget has
changed.

update() will handle all events, just like mainloop(), but returns as soon
as there's no longer an event to handle.

Jeff

from Tkinter import *
import time

class StupidProgress(Label):
    def __init__(self, master):
        Label.__init__(self, master, text="0%")

    def progress(self, percent):
        self.configure(text="%s%%" % percent)
        self.update()

abort = 0
def calculation():
    b.configure(state=DISABLED)
    c.configure(state=NORMAL)
    for i in range(100):
        print "calculation"
        time.sleep(.1) # represents doing .1 second of calculation
        if check_abort():
            b.configure(state=NORMAL)
            c.configure(state=DISABLED)
            l.progress(0)
            return
        l.progress(i)
    l.progress(100)
    c.configure(state=DISABLED)
    m.configure(text="Result: 42")

def check_abort():
    global abort
    if not abort: return 0
    abort = 0
    return 1

def do_abort():
    global abort
    abort = 1

app = Tk()
l = StupidProgress(app)
m = Label(app, text="(No result)")
b = Button(app, command=calculation, text="Find answer")
c = Button(app, command=do_abort, text="Never mind", state=DISABLED)

l.pack()
m.pack()
b.pack()
c.pack()

app.mainloop();