Re: Boggled By Bindings

FROM : Steven Kramer
DATE : Thu Oct 07 15:02:32 2004

Op 6-okt-04 om 12:57 heeft Patrick Machielse het volgende geschreven:

>> Because the array controller performs manual notification would be my
>> guess.

>
> That does _sound_ logical: if the controller doesn't automatically
> notify
> observers, but observers still get notified, the controller _must be_
> notifying observers manually.
>
> However, that begs the question: what would be the difference between
> manual
> and automatical notification? Either the obeject notifies observers,
> or it
> doesn't, in which case there isn't much use in registring or binding.
>
> Maybe I'm missing something, but wouldn't the method be better named
>    'notifiesObserversForKey:'?
>
> I don't see the difference between notifying and 'automatically'
> notifying?
> I fear I don't fully grasp the concept here :-(
>



Using manual notification, your 'set' method will do (something similar
to)

- (void) setMyKey: (int) newMyKey
{
   [self willChangeValueForKey: @"myKey"];
   myKey = newMyKey;
   [self didChangeValueForKey: @"myKey"];
}

Using automatic notification, your 'set' method will be transparently
overridden at run-time to send didChange/willChange. That is, the
bindings run-time support will send those messages before/after your
setMyKey is called. Your setter does not need to know anything about
KVO.


Regards

    Steven