> My understanding, which is vague and for which I have no references, is that
> it's handled in a manner similar to
> what was recently exposed via the associated references API (i.e.
> objc_setAssociatedObject and friends).
>
> That is, retain counts are stored outside of the instance.
In that case there is a danger that a pointer to whatever is referenced would
be transferred to the copy of the object, which is not what you want. One
could test it like this:
NSObject *a = [[NSObject alloc] init];
printf ("%d\n", [a retainCount]); // 1
NSObject *b = [[[NSObject alloc] init] retain];
printf ("%d\n", [b retainCount]); // 2
*b = *a;
printf ("%d\n", [b retainCount]); // 1
[b retain];
printf ("%d\n", [b retainCount]); // 2
printf ("%d\n", [a retainCount]); // ?
If the last printf prints 2, my scheme doesn't work as a and b must now be
referring to the same object at the Core Foundation object level. I am, of
course, far too lazy to test this or read up on it.
> Would be an interesting subject for Mr. Bumgarner to expound upon on his blog.
Yes it would. We're lucky it's Saturday or he would probably have already
poured cold water on the whole idea :).
Paul Sanders.
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