Weak References

[Bill Baxter]

On Thu, Aug 7, 2008 at 8:12 AM, Jason House <jason.james.house at gmail.com> wrote:
> A weak reference library exists but doesn't always work...

By doesn't always work you mean that it seems to you that sometimes it
prevents the target object from being collected, right?

But I think you said your only test case for this was something that
is not reproducible, correct?

Very frustrating to not be able to say for sure.  It would be a huge
help if the GC exposed some API for querying where a particular
pointer is being referenced.  Without that it's really hard to say
where the reference actually is coming from.

One possible gotcha that just crossed my mind:  I think the current GC
allocates chunks in an all or nothing manner -- hasPointers is just a
single bit.  So could it be that the fact that all Objects have a
vtable pointer mean that everything in an Object is always treated as
having pointers?

--bb

> PJP Wrote:
>
>> Is there any plan to add support for weak references to the D garbage collector?
>>
>> Weak references are references which don't prevent the object from being garbage collected.  If it has been garbage collected then the weak reference returns null.
>>
>> This is useful for things like resource caches, maintaining references to all instances of a specific class (ex: to implement an operation such as Window.minimizeAllWindows()), or to register a callback/listener with an object such that the registration won't prevent that object from being garbage collected.