On Nov 18, 2010, at 00:43, Andreas Grosam wrote: > Found this bug report related to this issue and the following explanation: > <http://www.mail-archive.com/llvmb...@cs.uiuc.edu/msg03631.html>: > >> --- Comment #1 from Fariborz Jahanian <fjahan...@apple.com> 2009-06-22 >> 21:34:42 --- >> This is part of the language spec. and cannot be changed. Two properties >> cannot use the same 'ivar' >> for their setter/getter synthesis. This is deemed necessary because it will >> be extremely error prone to >> allow the ivar changed via unrelated property operations. > > > Error prone for whom? The compiler writer or the programmer? > > IMHO, if this is error prone for the programmer, the rationale doesn't seem > to be reasonable enough to me, especially when the properties are readonly.
Really, there's no such thing as a readonly property, only a property that may or may not have a setter as well as a getter, and the compiler cannot determine absolutely whether or not there is a setter. (That's a consequence of the equivalence of @property-related and old-style property definition syntax, at least.) If setters are present at runtime, @synthesized ivar-sharing would certainly break KVO, and possibly would break @synthesized property atomicity. If ivar sharing is not allowed for @synthesize, the penalty to the programmer is having to write one set of accessors manually -- a trivial task. If ivar sharing were allowed, the penalty would be to open up the code to a number of KVO notification and multi-threading issues, especially when more code was added later -- a distinctly non-trivial burden. Are you sure the rationale is so insufficient? _______________________________________________ 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
