Re: RFC - Alternatives to gengtype

[Joern Rennecke <joern dot rennecke at embecosm dot com>]

Quoting Florian Weimer <fweimer@redhat.com>:

> On 11/18/2012 07:06 PM, NightStrike wrote:
>
> > What's wrong with std::shared_ptr?
>
> The pointer needs two words, and the per-object overhead for the
> reference counts etc. is four words, if I'm counting correctly.
>
> (Other forms of reference counting have less overhead, of course, but
> you were asking about std::shared_ptr.)

How about we require that in general, use of raw pointers to GC-able objects
are banned, and instead we require the use of a class (maybe obtained  
by template?) that is a pointer to the GC-able object, with a
special copy-constructor.  The copy-constructor marks the pointed - to
object as live.  GC traverses an object by performing a dummy copy and
destroying it.

If we need more than one operation, or mark-things-live when copying  
during normal operation causes too much overhead, we could select  
operations
to be performed by the copy constructor by adjusting some global state
(need not literally be a global variable - it might be a static member
variable in some class).