ANNOUNCE - graphics package

Vlad Dumitrescu <>
Mon Jan 19 15:07:01 CET 2004


From: "Luke Gorrie" <>
> Joe Armstrong <> writes:
> >   It turns out that with 20 odd protocol messages one can do *most* of
> > the  fun  things  that are  possible  with  X.  The entire  design  of
> > virtually all widget  sets (motif, GTK etc) seems  to be predicated by
> > the  desire to  simulate  concurrency  with callbacks.  In  ex11 I  do
> > *exactly the opposite* and expose the concurrency to the applications.
>
> Is it really concurrency they are simulating?
>
> I think what they're simulating is object-oriented programming. The
> callbacks are there to poke in behaviour so that e.g.  "Ok" and
> "Cancel" buttons do different things.

It is also a means to handle the complexity associated with GUIs. In a non-COPL,
this is a major issue. Once one is already in a concurrent environment, one's
mindstate is already handling several processes.

One possible show-stopper that I see is handling circular message paths, which
may lead to deadlocks.

I'd like to recommend some interesting reading
http://citeseer.nj.nec.com/fuchs95escaping.html, pleading for replacing the
event loop with continuation passing.

> I'm very curious to see how this experiment goes though :-).

Who isn't? :-)

/Vlad



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