Squeakers,
How many different update mechanisms exist in Squeak today? So far you have
the venerable change|update mechanism, the step mechanism (see
UpdatingStringMorph for example), likely some usage of the new exception
mechanism and possibly others I haven't found.  I think this will become
more of a problem if we don't provide some guidance as to which should be
used for what.

The step method relies on an external loop that will call it on a timed
basis.  Good news is its simple to use and integrates nicely with the
Morphic screen update process.  Bad news is you get an update whether or
not you need it based on a timer, not the state of the value being
displayed.  If the value requires a lot of processing each step, then you
waste cycles when the value has not changed.

The change|update mechanism relies on the developer building (and carefully
unbuilding) sometimes complex dependency networks.  This is how the old MVC
system updated everything.  Good news was it was entirely demand driven and
really enforced the MVC "seperation of concerns" paradigm.  Bad news was
the manual management of the dependency network.

I have used and like both methods but have also been frustrated when after
choosing one method I find I need the other.  Also, different morphs use
different methods, which can make coordinate difficult in complex UIs.

Any ideas on how we solve this one for the longer term?

Regards,
Sam

Sam S. Adams, IBM Distinguished Engineer, Software Group
tie line 444-0736, outside 919-254-0736, email: ssadams at us.ibm.com
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