From: Benjamin Peterson <bjsp123@...>
Date: 2002-07-27T00:49:25+09:00
Subject: Re: GUI's and the Rouge, Part III (yes, finally) 1/2


N.B.  This post is rather dull.

>> I agree strongly that asynchronous, hierarchical
>> message passing is a vital part of GUI
infrastructure.
>> I was under the impression that it revolutionized
GUI
>> programming quite a while back, though.


>* Rich messaging - you define strong message types
with arbitrary
>  content (in OpenUI that means potentially nested
arrays of
>  structures of...)
>* Hierarchical propagation against handlers having
the appearance
>  of dynamically-bound methods that receive the
message parameters,
>* Message broadcast down towards the leaf nodes
that's transparent
>  to the current delivery node.

Other than curses, I'm not sure I'm aware of *any* GUi
system that does *not* use asynchronous, hierarchical
messaging.  Even X used it -- and that was back in the
days of X!  

If you leave out the word 'strong' (they sure like
their void pointers over in Redmond), Windows has met
the above 3 items (in an inconsistent and obscure
way)for many years.  The proviso that 'no widget needs
to address any other' is a good one, and I can think
of nothing except Windows that meets it (maybe
Swing?).  In practise, of course, in Windows you *do*
often have to know the exact object you are talking to
so you can allow for all the inconsistencies.

I guess my conclusion is that having a powerful
messaging system is only useful if you have a set of
components so orthogonal that you actually can
broadcast a message to them and expect them all to do
something sensible with it.  And making those
components would be harder than making the messaging
system.

Benjamin Peterson


x