On Oct 26, 2010, at 2:33 PM, Rick Mann wrote: > Sure seems like a conceptual inconsistency, but I guess whoever designed the > language thought it was too expensive to return a zeroed struct.
It's an artifact of C compatibility. On each architecture, Objective-C messages follow the same parameter-passing rules as C function calls. On all modern architectures, the rules for returning a struct mean that objc_msgSend() has no way to know how big the returned struct is supposed to be, so it can't zero it. A few years ago we prototyped a compiler that added the nil check at the call site instead. Doing that everywhere was too expensive in terms of code size, but doing it for structs only might be practical. -- Greg Parker gpar...@apple.com Runtime Wrangler _______________________________________________ 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
