On Sun, Jul 6, 2008 at 11:25 AM, Bill Cheeseman <[EMAIL PROTECTED]> wrote: > on 2008-07-06 9:49 AM, Jean-Daniel Dupas at [EMAIL PROTECTED] wrote: > >> If __strong is so dangerous, why is it used in Cocoa (see NSDrawer, >> NSDateFormatter, NSNumberFormatter, NSKeyedArchiver, NSURL, Š) ? > > Those are interesting examples, especially NSDrawer. > > In NSDrawer, only the CFRunLoopTimerRef and CFRunLoopObserverRef iVars are > given the __strong keyword, while the CFRunLoopRef iVar is not. This > suggests to me that some very refined thinking is going on as to when to use > or not to use the __strong keyword. I wish I knew what all the relevant > considerations were.
CFRunLoopRefs live for the entire lifetime of their thread, so there's no need for __strong. But I would suggest that, as is the case for many other things, you don't need to duplicate Apple's refined thinking as to whether to use __strong or not. Do you want to keep a reference to a CF object? If yes, use __strong. End of story. You might use __weak if you want a zeroing weak reference. But this is extremely uncommon in a dual-mode framework such as what you're writing, because there's no equivalent to __weak in the non-GC world. Aside from wanting a zeroing weak reference, there's no real reason not to use __strong. The only reason would be for performance, and as we all know, premature optimization is the root of all evil. You *can* leave off the __strong keyword, provided you do your CFRetains and CFReleases properly and implement a -finalize method to clean things up. But this is less efficient, requires more brainpower, and is unnecessary. Mike
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