[Proposal] Weak reference implementation for D

[Sean Kelly]

On Thursday, 17 October 2013 at 08:09:24 UTC, Martin Nowak wrote:
> On 10/13/2013 09:47 AM, Denis Shelomovskij wrote:
>>
>>       * Alex's one from MCI:
>>
>> https://github.com/lycus/mci/blob/f9165c287f92e4ef70674828fbadb33ee3967547/src/mci/core/weak.d
>>
>
> I remember talking about this with Alex.
> He wanted to add some functions to the GC and this is what I 
> came up with based on the current implementation.
> It uses the synchronized GC.addrOf to check whether the loaded 
> pointer is still valid.

I'm afraid this is insufficient.  If a same-sized block is 
allocated before the dispose event is triggered, the WeakRef 
could end up pointing to something else.  It's a rare case (in 
the current GC, a finalizer would have to do the allocation), but 
possible.  This is what I referred to as the ABA problem the 
other day.  Not strictly accurate, but the effect is similar.