[Edu-sig] re: Pygeo, platforms, wx and Tk

[John Zelle]

Arthur,

In our VR work here, we do something very similar to what you are doing, 
but in an impoverished way. We use a Tk panel to control simulations in 
VPython. We have done this using threads and run on both Linux (our 
primary platform) and Windows with no hitch. The main difference, I 
think, is that we are not trying to communicate back from VPython to the 
Tk panel. We can spin and zoom in the Vpython window, and control other 
parameters through Tk. I guess I don't see any reason in principle that 
the two-way communication shouldn't work.

I suspect, can't tell without digging into your code, that the problem 
is that you end up making Tk calls from two different threads. That is 
strictly a no-no. It used to be the case that Tk calls could only be 
made in the thread that did the Tkinter import. I think that it's now OK 
to import, but only make calls in the thread the creates the main app 
(calls Tk() to get the root widget).

If you are not currently doing this, the next step to try is to create 
the Tk interface in main program, and have that initial program call the 
Tk mainloop. That means that the VPython stuff will actually be created 
and run in the separate thread. As long as mainloop() is in your initial 
thread (the one that imports Tkinter and grabs Tk()), I think that your 
approach will work under Linux and Windows.

If I get a little free time (hah!, it's finals week) I might try putting 
together a little demo to see that this two-way communication works. By 
the way, I hope you are using locks to protect any shared data across 
the two threads.

--John

Arthur wrote:

>Kent writes - 
>  
>
>>Thanks for the explanation. I didn't realize that the two panels are using
>>different GUI frameworks.
>>I don't know how to make that work...
>>
>>Kent
>>    
>>
>
>Well, that's 2 of us anyway ;)
>
>I'm suspecting that I will have more flexibility when VPython moves from
>GTK1 to GTK2.  But that might too, be wrong.
>
>FWIW, Arnd had recently mentioned coming to a solution that included the
>ipython interactive shell, when Idle could not serve his needs - because of
>its use of sockets.
>
>It turns out I can't use ipython to serve my needs with VPython, because it
>suffers from the same disease as did the old Idle - and which Idle solved
>with the use of sockets. It closes when I close a VPython display
>
>Life sucks ;)
>
>Art
>
>
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