> What's with the retain and release? I understand the issue of keeping myData > alive until you're finished with the interior pointer, but why [myData > release]? Is the release enough to keep myData alive even thought its > dispatch is short circuited under GC? And the retain is there to balance the > release in case someone executes under managed memory? Or did somebody mean > CFRetain and CFRelease?
-retain and -release are indeed enough to prevent myData from being collected (and therefore the interior pointer from going stale). The issue being worked-around is that of the compiler; during optimization, if you stop referencing myData, the compiler may decide to reuse the stack slot reserved for it. Once that reference disappears (assuming it was the last rooted, strong reference) myData will be collected. (Note that the short-circuiting issue is irrelevant, because it doesn't occur at compile-time - it happens in objc_msgsend.) Under managed-memory, the -retain/-release will ensure that the data object is kept alive until you're threw with the interior pointer, in the case that -getMyData didn't return a -retain/-autoreleased object. > It seems that [myData self] or [myData class] or some other harmless (return > value discarded) non-sequitor might be less confusing. It would point out > that this is an issue that is being worked around and not an ordinary part > of memory management. Indeed, you can choose to send myData any message you like - perhaps an appropriately-named macro would be more fitting. And of course if you're writing GC-only code then the -retain is unnecessary - for that reason sending myData -self at the end of the method would make a lot more sense. _______________________________________________ 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
