this is my first post here at Daniweb. Seems like an active and friendly environment.
I have very limited experience with programming in general, and even more so with GUI programming.
As the title suggests, I want to stop a while loop by the use of buttons.
When I press the start button, the program prints out "True" on the command window (I'm using windows). I am unable to press the stop button, the program just continues to print "True". I have to abort it to be able to stop.
How can I fix this?

Also, how can I print "True" on the panel instead of command window?


import wx

class whileLoop(wx.Frame):

    def __init__(self,parent,id):
        wx.Frame.__init__(self,parent,id,'whileLoop', size=(300,200))
        panel = wx.Panel(self)
        startButton = wx.Button(panel, label="start", pos=(10,10), size=(40,30))
        self.Bind(wx.EVT_BUTTON, self.startLoop, startButton)
        stopButton = wx.Button(panel, label="stop", pos=(60,10), size=(40,30))
        self.Bind(wx.EVT_BUTTON, self.stopLoop, stopButton)
    def startLoop(self,event):
        global flag
        flag = True
        while flag:
            if flag == False:
                print "True"
    def stopLoop(self,event):
        global flag
        flag = False
if __name__ == "__main__":
    app = wx.PySimpleApp()
    frame = whileLoop(parent=None,id=-1)

You have to use threading.

Take out the while, the mainloop is your loop. Set timer event for printing if flag is set. Button event just sets/unsets flag.

Take a real close look at the threading examples on this page (absolutely brilliant tutorial): http://www.blog.pythonlibrary.org/2010/05/22/wxpython-and-threads/

I recently developed wxPython code (using the first example in the link above) which updates a clock in the GUI every one second, and break from the loop by setting a flag value as you have in your code. You're close, but you'll definitely want to invest time into learning threading well.

commented: Nice link +2

Thanks for the replies guys. Looks like threading is the way to go. Thank you for the link convoluted, I'm having a look at the code. It might take some time before I understand it though :)

There a re several ways.

I think the most easy and accurate is the wx.Timer() method.
Very simple and handy.



# Then you use the 


## In your events method.

check it out ;)