Maybe the following helps to create a more robust version of the idiom, as it doesn't need 'using' at all: [snip] I think this won't work afterall. If I put a class into namespace A, I will get ambiguity. namespace A { namespace detail { template< typename T > void f( const T& ) { std::cout << 1 << std::endl; } template< typename T > void adl_f( const T& x ) { f( x ); } } template< typename T > void f( const T& x ) { detail::adl_f( x ); } // this is bad!! struct C {}; } namespace B { class C {}; void f( const C& ) { std::cout << 2 << std::endl; } } int main() { A::f( 42 ); A::C c0; A::f( c0 ); // error! B::C c; A::f( c ); } br Thorsten