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Re: Coalescing Updates in MVC?

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On 05/24/2012 07:02 AM, Stefan Ram wrote:
>    When a controller request many little changes of the model,
>    it might make sense to update the screen not after every little
>    update but only after the last update of the containing operation.
>
>    However, the model or view do not know after a little model
>    update whether there are more updates to come, so they
>    cannot decide whether to update now or later. Also the model
>    does not know whether an observer is a View or some other
>    entity that possibly might need to be notified of each
>    little update.
>
>    How is this usually handled?
>
>    I see one possibility to write the controller code as, e.g.,
>
> model.startCompoundChange();
> while( final Example example : container )model.add( example );
> model.endCompoundChange();
>
>    Where »startCompoundChange« and »endCompoundChange« will then
>    be broadcast to all observers of the model and the observers
>    now are free to only refresh the display after an »endCompoundChange«.
>
>    Another solution would be to send lightweight update
>    notifications to the View which then will start a timer to
>    update after, say, 0.1 s, ignoring all additional update
>    notifications for the same model that arive during that
>    time. But this might feel more sluggish to the end user,
>    because the visual feedback is delayed.
>
See Cocoa's NSNotificationQueue.
Some discussion is here:
<http://www.mikeash.com/pyblog/friday-qa-2010-01-08-nsnotificationqueue.html>

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Re: Coalescing Updates in MVC? Jeff Higgins <jeff@invalid.invalid> - 2012-05-24 08:47 -0400

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