On Wed, 21 Apr 2010, Greg Brown wrote:
[snippage]
One of the goals of MVC was to create an independent model which could
be presented through multiple concurrent views...But, and this is a big
*but*, what if elements and properties of the data model can be changed
through one or more of the tables?
...
Eh. You see where I'm going. "Load-n-store" is going to fall apart
here. Bi-directional event-driven binding between model and view (maybe
through a controller or whatnot) will save the day.
That's where an MVC framework comes in.
I don't see how that helps. But if you think I'm suggesting some kind of
MVC framework, then I can certainly understand why you think event-driven
data binding is a big ugly mess. Because MVC frameworks produce apps that
are big ugly messes.
Interestingly, I see you *are* using event-driven data binding for
list-based mutations. But if you change a property of an element of a
list, the list does not dispatch an event. The view remains ignorant.
This is also true of Flex, as I recall. You need to notify the list that
the data has changed.
Not true--not if the changed property is bindable. A list automatically
listens for change events from all of its members. If a bound property
changes, the member will dispatch a change event, the list will catch it,
wrap it as a kind of list change event, and dispatch it up the event
chain. No assembly required. :)
Where I'm coming from (data binding in Flex), doing this stuff with
custom event listeners/dispatchers is a real chore. Yeah, it can be
done, but it's a *lot* of work writing all that boilerplate.
One of the features we added for Pivot 1.5 is a pub/sub event model that
is meant to help facilitate application level messaging. You may find it
useful.
Hmmmm... I will check it out.
I'd also recommend looking into some of the client-side MVC frameworks.
I haven't done much work with them myself, but I suspect that they may
provide some of what you are looking for. On the other hand, if you
can't find something that fits the bill, why not create something
yourself and submit it as a contribution to the platform? ;-)
I would happily submit a set of patches if I thought they had a good
change of being accepted. Ha. Don't want to do all that work for
nuthin'.
I will suggest a design for some new functionality to support my beloved
event-driven data binding in a follow up message.
Cheers,
Michael
