Re: -[NSGarbageCollection disableCollectorForPointer:] ?
Re: -[NSGarbageCollection disableCollectorForPointer:] ?
- Subject: Re: -[NSGarbageCollection disableCollectorForPointer:] ?
- From: "Ken Ferry" <email@hidden>
- Date: Tue, 14 Oct 2008 23:08:13 -0700
Hi Michael,
NSPointerFunctionsStrongMemory|NSPointerFunctionsOpaqueMemory doesn't
make sense. You're meant to specify only one of the memory options and
only one of the personality options.
Due to the way the bitfield work, your invocation is the same as
NSPointerFunctionsOpaqueMemory|NSPointerFunctionsOpaquePersonality.
This is the mode in which the pointer array is completely hands-off.
It acts like a C array.
Try NSPointerFunctionsStrongMemory|NSPointerFunctionsOpaquePersonality.
That sounds right to me, though I get confused with the pointer
functions too.
-Ken
On Tue, Oct 14, 2008 at 9:43 PM, Michael Link <email@hidden> wrote:
> I have a situation where I create an NSPointerArray on the stack by:
>
> pointers = [NSPointerArray
> pointerArrayWithOptions:NSPointerFunctionsStrongMemory|NSPointerFunctionsOpaqueMemory|NSPointerFunctionsOpaquePersonality];
>
> I then go about adding a few objects a selector and a pointer (contextInfo
> that could point to anything even a non-object) to the pointer array.
>
> I then call:
>
> [[NSGarbageCollector defaultCollector] disableCollectorForPointer:pointers];
>
> The pointer array is then passed as the contextInfo for another method
> (which turns out to be a weak reference), but isn't garbage collected due to
> the previous call. The interesting part turns out that the object at index 0
> (NSError* in this case) in the pointer array is garbage collected (probably
> because it was a variable in the function that called us). The pointer array
> is configured to use strong references therefore index 0 isn't set to NULL
> and something else is located at that memory (sometimes a different object,
> sometimes garbage memory).
>
> If I use:
>
> [[NSGarbageCollector defaultCollector] disableCollectorForPointer:[pointers
> pointerAtIndex:0]];
>
> nothing bad happens and that object isn't collected.
>
> According to the documentation for disableCollectorForPointer: shouldn't the
> pointer array be considered a new root object, and none of it's pointers
> collected? Especially since it uses strong references?
>
> --
> Michael
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