On Jul 15, 2010, at 1:43 PM, Joaquin M Lopez Munoz wrote:
I agree with Andrew.
I disagree with Dave and Andrew. There is no natural concept around "a pointer plus some bits". These are packed together to save space, which is an aspect completely orthogonal to whatever purspose the pointer and the bits serve (separately).
To me, pointer_plus_bits should be as similar as possible to having two members, one a pointer the other the bits, so that for instance the following
class X { ... pointer ptr; bool b; };
can be rewritten as
class X { ... pointer_plus_bits<...> pb; };
so as to save memory, with as little change from the original situation as possible (for instance, instead of x.ptr one would say x.pb.ptr() and so forth). Overelaborating on an concept+bits concept seems to me to be missing the point.
Joaquin's right, of course. This is a lot like compressed_pair and probably ought to follow that model. In fact, maybe this should just *be* another optimization of compressed_pair. -- David Abrahams BoostPro Computing http://boostpro.com