Home Original page

Design Question: GUI+Threads.

Frithiof Andreas Jensen frithiof.jensen at removethis.ted.ericsson.dk
Fri Oct 24 07:52:35 EDT 2003 
Thaks for the reply,

"Brian Kelley" <bkelley at wi.mit.edu> wrote in message
news:3f97ee4a$0$573$b45e6eb0 at senator-bedfellow.mit.edu...
> Syver Enstad wrote:
>

> You might make your life easier by having the controller and the view be
> on the main thread and dispatch a new model to the work thread.

Hmm. I think that makes sense, since it is the GUI that "demands"
attention - I was doing sort-of  the other way round by having a thread
dispatching messages to models AND the GUI thread....

> Usually you can wrap model events into gui events and let the gui's
> mainloop sort them out and dispatch them to the controllers callbacks.

So, To make sure that I understand correctly:

I will have one Controller per Worker; the Controller interacts with the GUI
and it is the Controller that "understands" that the Worker is running in a
separate thread and maps GUI/Worker events across the thread boundary by
some means -

I was planning to use of a Dispatcher/Mailbox System:

The worker thread(S) blocks on an input queue until a message is in that
queue - then the worker thread process the message and places a result in an
output queue. The results in the output queue(s) of each worker are read by
the main thread and placed in the input queues of other workers or in the
GUI.....most of the time a worker will sleep, waiting for work.

The input and output queues would be owned by the workers, the "distribution
lists" i.e. which event goes where would be owned by a "Dispatcher" running
in the main thread .

While this is fine for Data, setting parameters etc. is clumsy: One needs to
setup a filter to sort parameter messages from the data and do special
processing - i would rather keep only data in the message loop.

> In python it is thread safe to set variables across the thread boundary,
> the model will have to check for these variables changing though.

...I will need locking in the models setXyz() methods so that I do not stomp
on some data that the worker thread is using?

> What gui framework are you using?

wxPython - in the hope that SciPy eventually will do a Python 2.2.3 release,
so that by the time I need it, I can get my hands on all those neat
Plotting, Numeric and Stats tools waiting to be liberated ;-)
More information about the Python-list mailing list