Hello Aleksey, Thank you for reply. Your suggestion looks much more attractive than code I have already implemented. But, yes, unfortunatly, there is still named auxiliary template. Anyway thanks, because by means of MPL I could write curious engine that takes mpl vector of types and builds runtime graph of available conversions between these types. The engine allows to find a chain of conversions that we have to make in order to convert any type to any if this conversion is somehow possible. Regards. -- Vyacheslav E. Andrejev System Architect, Excelsior, LLC AG> Or AG> AG> template< typename T > struct WhoConverted AG> : boost::mpl::transform< AG> types AG> , boost::is_convertible<T, boost::mpl::_1> AG> { AG> }; AG> AG> It's inconvenient to have to write (and name) an auxiliary template AG> that has no other uses, yes. AG> AG> At the moment, the above is the best you can have. I'm considering AG> implementing lambda scoping along the lines of AG> http://article.gmane.org/gmane.comp.lib.boost.devel/116000 for the AG> next release. AG> AG> HTH and sorry for the late reply, AG>