[boost] Re: Cyclic pointers - a comparison of known Boost efforts

From: Chuck Messenger (chuckm_at_[hidden])
Date: 2003-05-30 13:38:17

Gregory Colvin wrote:
> Thanks, but your description of cyclic_ptr is pretty far off the mark.

Sorry -- hopefully you'll forgive my ignorance. I'm just throwing out 
what I understand to be the case, in the hopes that someone (such as 
yourself) would set me straight...

> It does not maintain a global map, and copying cyclic_ptr cost the same
> as copying shared_ptr.

OK, I'll have to review the old messages again.  I thought someone had 
said cyclic_ptr used a global map.  Sorry.  I suppose better yet would 
be for me to study your actual *code*...

Do you do a raw scan of memory, like sp_collector, then?  (i.e. not 
perfect discovery)

> The special assignment mode is used only during
> the mark phase of a collection, and costs more or less the same as any
> other discovery method.

Suppose I have the structure:

     struct Image {
         char huge_image[ONE_ZILLION];
         cyclic_ptr<whatever> ptr;
     };

As I understand it, in order to discover 'ptr', you'd invoke operator=() 
on each Image structure you came to.  Correct, or incorrect?

     - Chuck Messenger