Re: [boost] Re: Callbacks Again

From: Asger Alstrup Nielsen (alstrup_at_[hidden])
Date: 2000-12-04 08:46:06

> This isn't quite enough. On most systems you also need to redraw 
> the view when the OS determines that the window needs to be 
> re-painted. So, I guess you need yet another callback that allows 
> you to fetch the data from the model.

I can understand that in some situations, you have to get access to the
raw model to repaint the view.  However, in the common case of a
"traditional" dialog, the underlying GUI toolkit will often take care of
the necessary caching of content to do repaints.

> In most cases I think decoupling views from the model like this is
> overkill. However if you do have a use for this decoupling this does 
> seem like a good way to go about it.

So we are reaching a consensus that life-time tolerance and
multi-casting are very useful properties that are worthwhile to offer in
a Boost library of signals/any_functions, even if this does have serious
ramifications on the design and implementation of the signals.

Whether such consequences are serious enough to warrant two or more
different kinds of signals, I can not tell.  I just hope that the
"full-scale" multi-casting and life-time tolerant signals will be
remembered as a worthwhile target.

My own experience is that such signals often change much of the design
of a program, because they allow many things to be implemented in an
easier way with less coupling, than traditionally.

Greets,

Asger Alstrup Nielsen