On Fri, Jan 9, 2009 at 8:40 PM, Graham Cox <graham....@bigpond.com> wrote: > Isn't guaranteed by the semantics of inheritance? I've specified the class: > [NSMutableArray ... and what I want it to give me... array]; And the fact > that NSMutableArray inherits NSArray ensures that anything that array can > do, NSMutableArray can do.
No, it means that NSMutableArray responds to everything NSArray responds to; there's no semantic guarantee. What if the subclass needs a different designated initializer, maybe one with more arguments? It would make sense for it to override the superclass's designated initializer to throw an exception. But without overriding the convenience constructor, this will blow up. --Kyle Sluder _______________________________________________ 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
