On Feb 2, 2011, at 12:37, Gordon Apple wrote: > I wrote the accessors for both lineSpacing and lineSpaceingNum and it at > least got through the compiler. I won't know if it really works until I get > the rest of the scaler/Number accessors done and try it.
I don't believe there's any real difficulty about writing the accessors as such. The danger is in tripping over KVO, and (IIRC) it can be hard to get 2 such properties to behave in lockstep as you would want them to do from a KVO point of view. If you make *only* a getter for the "...Num" version, then I think it's easy -- you just make it a dependent key via 'keyPathsForValuesAffecting...'. If you try to make a setter too, then it gets harder to make sure you don't generate too many KVO notifications -- or, worst of all, an infinite number, recursively. As best I recall, avoiding the recursion is not apparently that hard ... until you start to watch what undo/redo does. As usual with Core Data, undo tends to throw a wrench into the best laid plans. Perhaps I'm misremembering -- perhaps it all falls out neatly in the relatively straightforward case you've described -- but I do have memories of being in KVO hell for days or weeks trying to get this sort of thing working. That's why I suggested you might just avoid the problem completely. :) _______________________________________________ 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
