Joseph Gauterin wrote:
I Googled for tsoob, but couldnt' find any references to it. It would be helpful to have a look at tsoob::swap to see what's causing the ambiguity and how/if it could be resolved.
Also, I always intended for boost::swap to be called explicitly, rather than though ADL - it's supposed to hise the use of ADL from the user (no need for 'using std::swap' etc). If you use a fully qualified call, is there still ambiguity between boost and tsoob?
Of course, tsoob is just a made-up name... Upon further reflection, this is probably something that shouldn't happen, as it depends on the user wanting to use their own fallback swap function rather than std::swap. I was (however rightly or wrongly) concerned with code that does something like the following: -------- BEGIN CODE -------- #include <algorithm> // for std::swap #include <boost/utility/swap.hpp> namespace std { struct X; } namespace boost { struct Y; } namespace tsoob { namespace no_adl { #if 0 // Enabling this one gives ambiguities with std::swap template< class T > void swap(T& x1, T& x2) { /* fallback custom generic swap */ throw 0; } #endif #if 0 // Enabling this one gives ambiguities with boost::swap template< class T1, class T2 > void swap(T1& x1, T2& x2) { /* fallback custom generic swap */ throw 0; } #endif } } // namespace no_adl / namespace tsoob namespace tsoob_swap_impl { template< class T > void swap_impl(T& x1, T& x2) { using namespace ::tsoob::no_adl; swap(x1, x2); } } // namespace tsoob_swap_impl namespace tsoob { namespace adl { template< class T > void swap(T& x1, T& x2) { ::tsoob_swap_impl::swap_impl(x1, x2); } } // namespace adl template< class T > struct Z { }; } // namespace tsoob int main() { tsoob::Z< std::X > zx1, zx2; tsoob::adl::swap(zx1, zx2); tsoob::Z< boost::Y > zy1, zy2; tsoob::adl::swap(zy1, zy2); } -------- END CODE -------- At the end of the day, this is probably just not a Good Idea. However, I still think it might've been a good idea to insulate boost::swap from being found via ADL at all by inserting another namespace in there (so it's boost::adl::swap) rather than declaring boost::swap to have 2 template parameters to make it less preferred than std::swap. Evidently I can't think of a good example where this is a problem, though :/ Apologies for the noise, - Jeff