On Mar 26, 2013, at 1:40 PM, Quincey Morris <quinceymor...@rivergatesoftware.com> wrote:
> On Mar 26, 2013, at 13:11 , Conrad Shultz <conrad_shu...@apple.com> wrote: > >> If code expecting an NSOutlineView receives a TKOutlineView instance it may >> break or behave unexpectedly since it may well try to set a delegate >> conforming to <NSOutlineViewDelegate> but you have made your class require a >> delegate conforming to the more specific <TKOutlineViewDelegate>. > > Chris's delegate actually implements NSOutlineViewDelegate, doesn't it? > > Lee Ann's earlier suggestion of declaring TKOutlineViewDelegate to conform to > NSOutlineViewDelegate would prevent any remaining compiler complaints. Thus > the final declaration of the protocol would look like: > > @protocol TKOutlineViewDelegate <NSObject,NSOutlineViewDelegate> > > Would that take care of your concern? My concern is not a compile-time issue; it's a substitutability issue that may manifest at run-time. Consider the following hypothetical: 1) A required method is added to <TKOutlineViewDelegate>. 2) A class (say, a view controller) expecting an NSOutlineView is handed a TKOutlineView and sets its delegate to an object conforming to <NSOutlineViewDelegate> but *not* <TKOutlineViewDelegate>. This is valid since TKOutlineView is a subclass of NSOutlineView, and as such should be substitutable anywhere an NSOutlineView is expected. 3) The TKOutlineView then later attempts to send the <TKOutlineViewDelegate> message from #1 above to its delegate. 4) An exception is raised at run-time since the delegate actually conforms to <NSOutlineViewDelegate>, not <TKOutlineViewDelegate>. Admittedly this is a fairly specific combination of events that may never apply, but I wanted to make sure the OP is aware of it. -Conrad _______________________________________________ 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
