Weak references.

[Bill Baxter]

Michel Fortin wrote:
> On 2008-04-12 17:24:44 -0400, "Jarrett Billingsley" <kb3ctd2 at yahoo.com> 
> said:
> 
>> Is this possible at all?  Am I just not using Bill's weakref properly?
> 
> I've been using an alternate strategy in the D/Objective-C bridge for 
> the bridged object lookup table. Basically, I'm casting object 
> references to size_t (so they're no longer pointers) 

Yes, that's what the weak ref class does.

> and mangling the 
> pointers (so the garbage collector can't see them as pointers, I think 
> this is no longer be necessary). 

I agree that that's not necessary.

> When the bridged object gets deleted on 
> the D side, it removes its mangled pointer from the table.
> 
> So if your referenced object knows about its weak reference in the 
> table, you could implement it as such and don't have to worry about null 
> pointers polluting your table.

Good idea.  I was thinking to suggest something like that too.  A 
WeakRef class is not really an optimal way to keep track of a collection 
of weak refs.  In addition to null pointers polluting the table, there's 
also just the basic overhead of needing to create an extra object for 
each entry.  Ideally there would be WeakArray, WeakSet, WeakHeap... etc. 
  I think I've seen such things in some language.  Python maybe?

--bb