Re: KVO one-step listening but two-step notifying?
Re: KVO one-step listening but two-step notifying?
- Subject: Re: KVO one-step listening but two-step notifying?
- From: Daniel Jalkut <email@hidden>
- Date: Fri, 23 Dec 2005 00:56:10 -0500
Hmm - I'm confused. What's the distinction between:
1. It's OK to to invoke will/didChange without a change actually
happening (just inefficient).
2. Not alright to invoke *both* after a change has occurred (to tickle).
I'm assuming that *both* in the second essentially means "will/
didChange". If it's OK to do when nothing has happened, how can it be
wrong (dangerous, not just inefficient) to do so some time after a
change has already occurred? Isn't that the same (safety-wise) as
"nothing has happened"?
I'm acutely interested because I might have some lurking bugs in my
code that need to be addressed.
Daniel
On Dec 22, 2005, at 8:34 PM, mmalcolm crawford wrote:
On Dec 22, 2005, at 5:22 PM, Daniel Jalkut wrote:
I think mmalcom's gut feeling that you should design things in
term of dependent objects is probably wise. But I have gotten away
with "blank" will/did-change combos, and I assume they must be
safe. It's not up to the observer to decide how I change the
values they are observing.
As noted in my original reply, invoking will/didChange without a
change actually happening is alright (just inefficient). What is
*not* alright is to invoke *both* methods *after a change has
already occurred* (i.e. to "tickle" a bindings update). At some
stage, this will cause a problem...
mmalc
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