Thanks for the report, I'll take a look. I don't think I'd tested
@synchronized() with a class as an argument - it seems like a very strange
thing to do when there are safe ways of achieving the same result with much
less overhead.
By the way, creating singletons like this is entirely wrong. The correct way
of creating a singleton is to do it in +initialize, like this:
+ (void)initialize
{
if ([MyClass class] == self)
{
MY_SINGLETON_VARIABLE = [[self alloc] init];
}
}
Then the runtime will ensure:
1) This method runs to completion before any other messages are sent to the
class.
2) This method runs exactly once.
Creating singletons any other way introduces potential race conditions.
David
On 27 Feb 2010, at 15:54, [email protected] wrote:
> Hi!
>
> I am doing something like:
>
> @synchronized(self)
> {
> if ( MY_SINGLETON_VARIABLE == nil )
> {
> [[ self alloc ] init ];
> }
> }
>
> Looks like in sync.m:initLockObject my objects ISA pointer gets changed. So,
> at the time "alloc" is called the message lookup simply fails.
>
> TOM
>
>
>
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