> On Apr 24, 2017, at 10:07 AM, Richard Charles <rcharles...@gmail.com> wrote: > >> >> On Apr 23, 2017, at 11:27 AM, Charles Srstka <cocoa...@charlessoft.com >> <mailto:cocoa...@charlessoft.com>> wrote: >> >>> On Apr 20, 2017, at 3:06 PM, Quincey Morris >>> <quinceymor...@rivergatesoftware.com >>> <mailto:quinceymor...@rivergatesoftware.com>> wrote: >>> >>> Where I disagree is in your much stronger claim that a computed property is >>> *necessarily* a dependent property. I think this is just false. The Swift >>> distinction between computed and stored properties is syntactic and has >>> nothing to do with KVO**. A KVO-observed computed property should >>> therefore, according to the documented principle, be marked “dynamic”. For >>> anyone following your extended principle, if it’s also a dependent >>> property, they can omit the “dynamic”. If not, not. >> >> Do you have any example of a property not backed by anything where KVO even >> makes sense? The whole purpose of KVO is to watch changes to values, and if >> there’s no value, it seems like the wrong tool. > > I have a property that returns an array. A setter for this property makes no > sense. The property returns a collection of managed objects that is the > composite value of several to-many relationships. > > This property is KVO compliant and bound to the NSContentArrayBinding of an > array controller. > > There is most likely more than one way to do this but I find using bindings > convienient. You can bind to a KVO compliant property. You can't bind to a > notification. > > This is in an Objective-C project that requires interoperability with a C++ > library. So using Swift is not possible but maybe someday it will be. > > --Richard Charles
But it sounds like this property *is* backed by a value. The backing is the collection of managed objects. I take it you’re simply watching changes to the C++ source data and calling didChange/willChange when appropriate—basically translating one type of notification to another. This makes perfect sense—although not having a setter, being marked ‘dynamic’ would not change its behavior at all. What Quincey seemed to be referring to was a property that was not backed by any kind of persistent value. Presumably, this property would also have a setter, since otherwise ‘dynamic’ isn’t really in play. I’m very curious as to what the applicability of such a thing would be, because I can’t think of any myself. Charles _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
