Hi, Can someone help me. I have defined a boost::variant<long long,double,std::string> with a visitor which issues an increment. The visitor derived class below works fine for std::string and long long only within the visitor, but as soon as I add a double, I get an ambiguous call compile error (error below). I'm guessing when T within the prop_increment class is an int, the compiler doesn't know whether to use the long long version of the operator() or the double version. Does anyone know how I can get around this when I apply the visitor? Interestingly enough, if I add an int to the boost::variant template list the error goes away. ------ Compile Error ------ Error 44 error C2668: 'boost::detail::variant::make_initializer_node::apply<BaseIndexPair,Iterator>::initializer_node::initialize' : ambiguous call to overloaded function \boost\variant\variant.hpp 1273 ----------------------------- ------ Visitor Class ----------- class prop_increment : public boost::static_visitor<> { public: template <typename T, typename U> void operator()( T &, const U & ) const { return; } template<typename T> void operator()(T & lhs, const T& rhs) const { lhs += rhs; } }; ------------------------------------ boost::apply_visitor(prop_increment(),prop1,prop2); ---- Visitor Call ------------------- Thanks