On Wed, Jun 03, 2009 at 07:38:51PM +0100, Joseph Gauterin wrote:
I'm pretty sure the intent of the code is to replace the generic swap-by-copy-assignment std::swap template
The intent is to replace std::swap with a call a specialized swap (via ADL) or to call boost::detail::move_swap::swap otherwise. std::swap will never be called from that function, unless std::swap is picked up by ADL - in which case it probably *is* specialized for the type being swapped. By making boost::detail::move_swap::swap less specialized than std::swap, you can stop the ambiguity that happens only in this case.
OK, yes, I'll buy that. I'm not convinced that there is nothing in ::std without a std::swap specialization, but I guess I am convinced that for any of those things it makes no difference whether we call std::swap or detail::move_swap::swap. Maybe. I think I will write an additional test case that checks a specialized swap is being called if it exists, just to make me feel safer. I won't be able to get round to this until Monday, though, as I'm out of town, so if anyone wants to do it before then, I won't be offended. :-) Thanks for all your help. -- "Sometimes it's a Boat, and sometimes it's more of an Accident. It all "Depends on what?" depends." "On whether I'm on the top of it or underneath it." -- A. A. Milne, ‘Winnie-the-Pooh’ http://surreal.istic.org/