> On Aug 5, 2015, at 5:00 PM, Rick Mann <rm...@latencyzero.com> wrote: > >> On Aug 5, 2015, at 16:57 , Charles Srstka <cocoa...@charlessoft.com >> <mailto:cocoa...@charlessoft.com>> wrote: >> >> I get that error any time I try to subclass *any* enum. I don’t think enums >> are supposed to be subclassable. > > Guess I'll submit a bug. Seems perfectly reasonable to do.
It’s part of the language design that only classes support inheritance, not structs or enums. Basically, subclassing pass-by-value types is problematic. For example, what happens when you assign a SubclassStruct value to a variable of type BaseStruct, or pass it to a function parameter of type BaseStruct? Do the extra instance variables get chopped off when it’s copied? What happens if you call a BaseStruct method that was overridden in SubclassStruct? C++ lets you do this, but it can lead to really nasty problems, so style guides like Effective C++ recommend avoiding it. —Jens _______________________________________________ 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
