On Mar 12, 2010, at 9:58 AM, Alexander Spohr wrote: >> I'll try this, but I don't expect it to work, because there can be 0 or more >> relationB object's, and each of those object's can have 0 or more relationC >> objects, and just 'plain' dot syntax won't produce a superset of relationC >> objects > > If you have 0 Bs, you’ll have an empty array > If you have Bs without Cs they just wont fill anything into the array. > > *methinks* it might be that you get some NSNull in there for the empty Cs. > > But no, this should not happen because the relationship itself is an NSSet, > not a pointer that can be nil. > > From NSSet’s valueForKey: > Discussion > The returned set might not have the same number of members as the receiver. > The returned set will not contain any elements corresponding to instances of > valueForKey: returning nil (note that this is in contrast with NSArray’s > implementation, which may put NSNull values in the arrays it returns). > > valueForKeyPath: is just a recursive or iterative call: > "Discussion > The default implementation gets the destination object for each relationship > using valueForKey: and returns the result of a valueForKey: message to the > final object." > > atze > >> (from my understanding of KVO and KVC). > > what is your understanding of KVC?
That it wouldn't do this merging of set's automatically. And I did just try it, and got a binding error: Cocoa Bindings: Error setting value for bound property instanceOfA of object <controllerclass: 0x100675780>: [<_NSFaultingMutableSet 0x1006eab90> addObserver:forKeyPath:options:context:] is not supported. Key path: relationC I figured it would be something like this, which is why I was looking at the @unionOfSets operator in particular (as that's exactly what this is, a union of all sets of relationC objects from a set of relationB objects. Eli _______________________________________________ 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
