PythonCard - My app stuck when button clicked
daved170
daved170 at gmail.com
Thu May 14 02:57:02 EDT 2009
On May 13, 7:42 pm, Dave Angel <da... at ieee.org> wrote:
> daved170 wrote:
> > Hi there,
> > I'm newbie in pythonCard.
> > I have an application with 2 buttons : START , STOP
> > Start execute a while(1) loop that execute my calculations.
> > Stop suppose to raise a flag that will end that loop.
>
> > Whenever I pish the START button my GUI is stuck. the calculation
> > executes but I can't push the STOP button.
>
> > I added thread that START start a thread that execute my calculations.
> > I also added a Global variable that will hold the indication if the
> > loop should continue.
> > The problem now is that the thread ignore that variable and loop
> > forever.
>
> > Is there a simple way to make sure that the GUI won't stuck (without
> > threads)?
> > And if there isn't such way I would appriciet it very much if anyone
> > could post an example of how to make my thread read that variable
> > Thanks
> > Dave
>
> I don't know PythonCard, but most GUI's are similar enough that the
> concepts will work, even though the details differ. I'll assume that
> PythonCard has a traditional event loop, from which all events are
> dispatched.
>
> If your loop is fairly small, then you should keep it to one thread.
> Debugging it will usually be much easier. The trick is to break the
> task into pieces (each piece might be once around what is now a loop),
> and invoke one piece each time the event loop empties. I can't tell you
> how to do that without seeing your loop, but it's not usually very hard.
>
> Now, there is some way of POSTing an event to the event loop. That puts
> the event *after* all the events that are already there, but returns
> control immediately. So create a custom event, and POST it from the
> START button's button-pressed event. That will fire off one "loop" of
> the special task, in other words, make one function call to your new
> function. Then at the end of the function, POST it again, unless the
> STOP button has been pressed in the meantime.
>
> An optimization for this is to use coroutines, which are usually done
> with a generator. It's much trickier to describe, but much easier to
> accomplish. Roughly, you'd take your existing loop, and put a yield
> statement in it at appropriate place(s). Then the custom event is
> simply a call to the .next() function of that generator.
>
> Now, threading isn't that tough either, depending on how much data is
> being shared between the thread and the main program. You say that
> sharing a global flag isn't working, but it should. So how about if you
> show us some code, and somebody'll spot the trouble. For example, is
> the thread defined in the same module as the App? Global only shares
> between a single module. Another reason globals might seem to fail is
> if you tried to do mutual imports between two or more modules. (A
> imports B, which imports A). Sometimes that fails in mysterious ways.
>
> Make a simple (stripped) example of what you're trying, and we'll try to
> find the problem. Without concrete code, we end up with ambiguities
> like the above usage of two different meanings for "the loop."- Hide quoted text -
>
> - Show quoted text -
Thank's Dave,
Here my code, It's a very simple app. the Start button starts a TCP/IP
communication and the Stop should dtop it and kill the client.
I'll be thankful if you'll be able to spot my mistake.
Thanks again
Dave
#Global Variable
bStopLoop = False
#Global Function
def execute(sockObj):
while(!bStopLoop):
str = sockObj.recv(1024)
tmpStr = "Hello " + str
sockObj.send(tmpStr)
#Thread handle class
class myThread(threading.Thread):
def __init__(self,sockObj):
threading.Thread.__init__(self)
bStopLoop = False
self.sockObj = sockObj
def run(self):
execute(self.SockObj)
# GUI
class GUI(model.Background)
def on_Start_mouseclick(self,event):
try:
event.target.enable = False
event.target.redraw()
self.components.Start.enable = False
self.currThread = myThread(self.sockObj)
self.currThread.Start()
wx.SafeYield(self)
self.components.Start.enable = True
except:
.....
def on_Stop_mouseclick(self,event):
bStopLoop = True
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