Benji Smith wrote:
> The only comment I'd like to add is this:
> 
> At the same time as we're thinking about how to use a precise collector instead of a conservative collector, we should also think about how to implement a generational copying collector, since it might be necessary to add new constructs to the core language (pointer pinning, for example) to facilitate the new collector semantics.

Personally, I'm not convinced that a traditional moving GC will be the way to go in D.  Unless we are given some way to obtain type info for data on the stack and in the static data segment, anything directly referenced by these regions would have to be implicitly pinned.  And typically, long-lived data is referenced directly from such links.  A programmer could work around this limitation by using proxy classes, but this seems like a lot of trouble just to allow for generational garbage collection.  However, there are variants on the idea that sound like they have potential, one of which I believe is being discussed.  As for pointer pinning--it's fairly easy to add to the GC, so I don't see that as an obstacle to future design.  The bigger problem is sorting out efficient implementations of Object.opHash and such for objects whose only persistent uniquely identifying characteristic is their address.


Sean