"Jeffrey Carter" <jeffrey.carter@boeing.com> a �crit dans le message news: 3CC5F5B0.DBC6A6B8@boeing.com...
> "Warren W. Gay VE3WWG" wrote:
> >
> > One area that has traditionally been a sore point in Ada and GUIs is
> > the client_data parameter in callbacks.  Gtk kind of hacks around this,
> > but I'd like to see a more perfect (Ada95) solution to this problem.
>
> I consider callbacks themselves a sore point. Callbacks are a hack to
> handle the inherent concurrency of a windowing system in a sequential
> language such as C. The natural approach is to associate a concurrent
> blocking queue of events with each window; the application has a task
> per window obtaining events from this queue and deciding what to do with
> them.
>
<PLUG>
The issue of call-backs (and more generally of the listener paradigm) will be addressed in a paper that I present at the
Ada-Europe/Vienna conference.
</PLUG>

--
---------------------------------------------------------
           J-P. Rosen (rosen@adalog.fr)
Visit Adalog's web site at http://www.adalog.fr