[boost] Re: smart_ptr suggestion: Support decrementing shared_ptr'scount,forself-references

From: Chuck Messenger (chuckm_at_[hidden])
Date: 2003-05-27 16:48:00

Larry Evans wrote:
> Chuck Messenger wrote:
> [snip]
> 
>> In general, the abstraction is: you have a group of intra-referential 
>> objects.  When any of the group is constructed, they are all 
>> constructed (so that the master count is temporarily > 1), and the 
>> master count is reset to 1.  When the master count goes to 0, the 
>> group is destructed. Hence, the group only remains alive as long as 
>> there are any external references (and as long as the intra-group 
>> references remain static).
>>
>> Could a standard smart pointer be designed to encapsulate this 
>> abstraction?  Hmmm....
> 
> Just FYI, this "abstraction" is the basic idea behind recoverying
> cycles in:
> 
>   
> http://www.cs.kent.ac.uk/people/staff/rej/cgi-bin/searchbib?pattern=Cyclic+reference+counting+with+lazy+mark-scan. 
> 
> 
> Chrisopher's altorithm:
> 
>   
> http://www.cs.kent.ac.uk/people/staff/rej/cgi-bin/searchbib?pattern=Christopher+Reference+count+garbage+collection 
> 
> 
> is basically the same, except the "group" is the whole heap.  Christopher's
> is the basis of Colvin's cyclic_ptr:
> 
>   http://groups.yahoo.com/group/boost/files/smart_pointers/cyclic_ptr/

Thanks -- it looks very interesting.

I did some googling, to see what its status is.  Seems it hasn't been 
mentioned much since the flurry of activity in Jan-May 2001.  Pity, 
since if it works "as advertised", it seems pretty useful.

     - Chuck Messenger