On Tue, Apr 5, 2011 at 12:10 AM, Chris Hanson <[email protected]> wrote: > On Apr 4, 2011, at 12:38 PM, Bing Li <[email protected]> wrote: > >> if (nil == defaultMenu) >> { >> @synchronized(self) >> { >> if (nil == defaultMenu) > > Don't do this. I don't mean just in Cocoa either, I mean don't do it ever. > It's an anti-pattern called "double-checked locking" and it's fatally broken > under most languages' memory models. > > If you want to initialize a value once-and-only-once, use dispatch_once or > (if you need to support an OS version without GCD) use pthread_once.
It's also worth pointing out that NSMenu is not thread safe, and should never be accessed off the main thread. So the locking is pointless anyway! _______________________________________________ Cocoa-dev mailing list ([email protected]) 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 [email protected]
