After reading a recent Joel on Software article ( http://www.joelonsoftware.com/items/2003/10/13.html ) and the discussion it generated, I decided to try to write some sort of general strong typedef. I've started out by creating a specific class similar to what would be generated by a `typedef strong_typedef<tag,wrapped_type> name;`, and am trying to use enable_if and is_convertible to allow explicit construction from any type that can be converted to the wrapped type. Unfortunately, I keep getting errors such as the following: main.cpp:36: error: no matching function for call to `position::position(int)' main.cpp:7: error: candidates are: position::position(const position&) main.cpp:14: error: position::position() Compiler version: g++ (GCC) 3.3.5-20050130 (Gentoo Linux 3.3.5.20050130-r1, ssp-3.3.5.20050130-1, pie-8.7.7.1) Here's the cut down code. I'd greatly appreciate it if someone could point me towards what I'm doing wrong. Hopefully I'm just missing something elementary. ( I'm quite new to these boost features. ) On a side note, has anyone come up with a good method of wrapping these rather long SFINAE calls? Thanks, - Scott McMurray // begin code // #include <boost/type_traits.hpp> #include <boost/utility/enable_if.hpp> class position { public: typedef position my_type; typedef unsigned wrapped_type; private: wrapped_type m_data; public: position() {} // This works fine explicit position(boost::enable_if< boost::is_convertible<int, wrapped_type>, int>::type f) : m_data( f ) {} /* // But if I try this, I get the errors template <typename fT> explicit position(typename boost::enable_if< boost::is_convertible<fT, wrapped_type>, fT>::type f) : m_data( f ) {} */ }; int main(int argc, char* argv[]) { position x = position(5); } // end code //