# safe_threading_demo.py

#!/usr/bin/python
# -*- coding: iso-8859-1 -*-

# safe_threading_demo.py

import Tkinter,threading,time

class MyProcess(threading.Thread):
    def __init__(self,startValue):
        threading.Thread.__init__(self)
        self._stop = False
        self._value = startValue

    def run(self):
        while self._value>0 and not self._stop:
            self._value = self._value - 1
            print u"Thread: I'm working... (value=%d)" % self._value
            time.sleep(1)
        print u"Thread: I have finished."

    def stop(self):
        self._stop = True

    def result(self):
        return self._value

class MyGUI(Tkinter.Tk):
    def __init__(self,parent):
        Tkinter.Tk.__init__(self,parent)
        self.parent = parent
        self.initialize()
        self.worker = MyProcess(15)
        self.worker.start()  # Start the worker thread

    def initialize(self):
        ''' Create the GUI. '''
        self.grid()
        button = Tkinter.Button(self,text=u"Click Me To Stop",command=self.OnButtonClick)
        button.grid(column=1,row=0)
        self.labelVariable = Tkinter.StringVar()
        label = Tkinter.Label(self,textvariable=self.labelVariable)
        label.grid(column=0,row=0)
        self.labelVariable.set(u"Hello...  ")

    def OnButtonClick(self):
        '''' Called when button is clicked. '''
        self.labelVariable.set( u"Button clicked" )
        self.worker.stop()  # We ask the worker to stop (it may not stop immediately)
        while self.worker.isAlive(): # We wait for the worker to stop.
            time.sleep(0.2)
        # We display the result:
        self.labelVariable.set( u"Result: %d  " % self.worker.result() )

if __name__ == "__main__":
    app = MyGUI(None)
    app.title('My Application')
    app.mainloop()