[wxPython-users] Re:

Josiah Carlson jcarlson at uci.edu
Wed Oct 25 17:39:57 CEST 2006


Michael S <msherman77 at yahoo.com> wrote:
> If I create a threading.Thread derived class, and run
> the wxPython code in the main thread; using a lock,
> will I be able to suspend the Thread, even though it
> will run the C code, which is essentially a while loop
> looping through millions of lines of a text file?

If all your C code is doing is looping through lines in a text file, you
can rewrite it fairly reasonably in Python via 'for line in open(fn):'.

In terms of locks, you have to use a lock that can be acquired by either
thread (GUI or C), but that won't necessarily give you what you want;
the GUI thread in wxPython may still not like being called directly.

If you want the ability to easily restart your C code, you may want to
consider at least looking at the following page on coroutines in C:
http://www.chiark.greenend.org.uk/~sgtatham/coroutines.html .  It would
allow you to do all of your GUI manipulation/updating in Python without
having to worry about locks or calling Python code from C.

 - Josiah


> --- Josiah Carlson <jcarlson at uci.edu> wrote:
> 
> > 
> > Gabriel Genellina <gagsl-py at yahoo.com.ar> wrote:
> > > At Tuesday 24/10/2006 23:25, Michael S wrote:
> > > 
> > > >I extended part of my program in C, since that
> > part
> > > >was too involved for Python. Now when I import
> > the
> > > >module I created and call its functions, I am
> > trying
> > > >to feedback some information bac to my wxPython
> > > >program. The function runs for a while and I
> > wanted to
> > > >update a progress bar, but when I call the
> > function of
> > > >my new module, wxPython doesn't respond when
> > wx.Timer
> > > >is supposed to fire.
> > > 
> > > Does your extension run on a separate thread? I
> > guess not. So the 
> > > wxPython code does not have a chance to run.
> > > Do it the other way: from your C code, call a
> > Python function which 
> > > in turn updates the progress bar (and keep it
> > simple!)
> > 
> > Unless the GUI thread has a chance to take passes
> > through the wxPython
> > mainloop, the progress bar, etc., may not actually
> > be updated on some
> > platforms.
> > 
> > Mr. Sherman would likely be better off creating a
> > new thread which
> > handles processing, which could update a C global
> > variable, which the
> > GUI thread can poll to update its progress bar, etc.
> >  Alternatively, if
> > the processing can be broken down into smaller
> > pieces, the secondary
> > thread can call the pieces and post events back to
> > the GUI thread to
> > update the progress bar (via explicit wx.PostEvent
> > or implicit
> > wx.CallAfter).
> > 
> > 
> >  - Josiah
> > 
> > 
> >
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