WeakRefs for a CPP->D wrapper

[Abdulhaq]

On Sunday, 12 January 2014 at 10:48:15 UTC, Abdulhaq wrote:
>>
>> No, try this:
>> import std.stdio;
>> class X {}
>> void foo(X x) { writeln(cast(void*) x); }
>>
>> void main() {
>>         X x; // null reference by default.
>>         writeln(cast(void*) x);
>>         foo(x);
>>
>>         x = new X;
>>         writeln(cast(void*) x);
>>         foo(x);
>> }
>
> Thanks Tobias that indeed works, unfortunately storing the 
> address as ulong in an AA does not seem to be defeating the 
> garbage collector!
>
> I guess I'll have to go for a WeakRef implementation, I'll try 
> Robert's implementation in signals, but I'd really like to know 
> how long it is likely to last as a working weak ref (in terms 
> of the D GC changing etc.) and if I'm taking the right approach.

Sorry to reply to my own message, looking at Robert's 
InvisibleAddress class I think he's hiding the address from the 
GC by e.g. rotating the bits in the ulong. He's also made it all 
thread safe - I certainly don't understand the details but it's 
given me some ideas.