Le 9 août 2012 à 02:01, Greg Parker <gpar...@apple.com> a écrit :
> On Aug 8, 2012, at 4:52 PM, Graham Cox <graham....@bigpond.com> wrote:
>> I see that NSCopyObject is deprecated as of 10.8 (but is still being used
>> internally).
>>
>> This is going to be fun moving forward :) I'm not sure how binary
>> compatibility is going to be maintained as NSCopyObject disappears, for
>> example, in a cell subclass I might have:
>>
>> - (id) copyWithZone:(NSZone*) zone
>> {
>> MyCell* copy = [super copyWithZone:zone];
>>
>> [copy->someInternalPointer retain];
>> return copy;
>> }
>>
>> This relies on the existing behaviour of NSCopyObject not retaining pointers
>> it has copied.
>>
>> If in future NSCell changes to use some alternative such as the ARC stuff
>> you mention, this will now leak due to the extra retain. If I don't do the
>> retain, it will crash on older systems due to the (later) over-release.
>
> It's possible that NSCopyObject will live on in NSCell forever due to binary
> compatibility constraints like you described. I don't know if there are other
> plans here.
>
>
>> Is there a solution to this that will work forwards and backwards?
>
> Use ARC in your subclass. Then you can write your subclass so that it doesn't
> care how the superclass is implemented.
>
> This code works under ARC whether or not the superclass used NSCopyObject:
> - (id) copyWithZone:(NSZone*) zone
> {
> MyCell* copy = [super copyWithZone:zone];
> copy->someInternalPointer = [copy->someInternalPointer copy];
> return copy;
> }
>
I guess you mean: copy->someInternalPointer = [someInternalPointer copy];
If you use copy->someInternalPointer, you rely on the fact that the superclass
already init it with the previous value.
-- Jean-Daniel
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