On Tue, Apr 5, 2011 at 12:10 AM, Chris Hanson <c...@me.com> wrote:
> On Apr 4, 2011, at 12:38 PM, Bing Li <lbl...@gmail.com> 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!
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