Re: [NSObject setValue:forUndefinedKey:] no longer requires explicit KVC notifications?
Re: [NSObject setValue:forUndefinedKey:] no longer requires explicit KVC notifications?
- Subject: Re: [NSObject setValue:forUndefinedKey:] no longer requires explicit KVC notifications?
- From: Gabriele de Simone <email@hidden>
- Date: Sat, 8 Aug 2009 19:24:32 -0400
On Aug 8, 2009, at 2:37 PM, Keary Suska wrote:
It used to be that if you overrode -[NSObject
setValue:forUndefinedKey:] your own subclass was responsible for
calling -[NSObject will/didChangeValueForKey: so that bindings and
observers would work as expected.
That was fine, since it allowed one to provide different
implementations depending on the key, and to generate (or not) KVC
notifications. It seems that a recent update to Mac OS X (perhaps
10.5.8?) has changed this behavior. It seems that as long as you
override setValue:forUndefinedKey:, KVC-compliant notifications are
automatically generated for the given key.
Can anyone confirm this? This is an "interesting" change to the
Cocoa framework that probably interferes with any class that
overrides [NSObject setValue:forUndefinedKey:].
Calling will/didChange should never have been necessary, and in fact,
the setter sequence should be automatically wrapped with the calls, as
long as automatic notification is on. AFAIK, this has always been the
case and hasn't changed recently. There may be more side effects than
before, but I don't recall.
HTH,
Keary Suska
Esoteritech, Inc.
"Demystifying technology for your home or business"
The KVC infrastructure did not always generate value-changed
notifications for setValue:forUndefinedKey: overrides. Doubting my own
sanity (always a good approach, IMO) I searched for, and found some
evidence of this in an old discussion:
http://www.cocoabuilder.com/archive/message/cocoa/2006/10/12/172593
When did you start using setValue:forUndefinedKey: in your own code?
It's quite possible that Apple changed this behavior a while back
(with the 10.5 runtime?) and I wasn't paying enough attention. I doubt
too many developers are overriding setValue:forUndefinedKey:, but this
change means their code would need some cleaning up.
Thanks,
Gabe
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