Le 6 juil. 08 à 17:35, Michael Ash a écrit :
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 aregiven the __strong keyword, while the CFRunLoopRef iVar is not. Thissuggests 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 relevantconsiderations 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
I think the rule may be: use __strong for retained/copied ivars, and nothing for assigned ivars.There is no equivalent of zeroing ref, but weak ref are really common in Cocoa. For example, delegate are not retain. the Notification center does not retain observers, and the drawer probably does not retain the runloop.
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