Phillip J. Eby wrote:
At 02:03 PM 9/24/2005 -0700, John Anderson wrote:
UI state is persisted in the block. After all, in the MVC paradigm
for UI, the block is the model and the widget is the view. When the
widget tells us of a change like the position or state of a window,
we need to store it in the block and typically the UI is already up
to date so there is no need for a notication.
In which case, the update should be convergent, right? I mean, you'd
be setting it to the same value that's already there, so there
shouldn't be any further notifications after the first one, or else
I'd say the notification system is generating spurious notifications.
Or are you saying the problem is that you don't want even *one*
notification in this case?
Yes in some cases we don't want any notifications. Consider this case:
wxWidgets handles the click, updates the selection on the screen and
tells us about the change. As a result we store the change in the
selection. The selection is a change to data that causes a notification,
which causes a new unnecessary update to the screen. So typically when
the system updates the screen we only need to save the change. When the
data changes as a result of something the system can't handle we want
notifications so we can update the screen. There are many other similar
examples like this that crop up in practice.
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