Is it possible to change a variant's type within a visitor function? What I'd like to do is something like this: typedef boost::make_recursive_variant< int, std::string, std::vector<boost::recursive_variant_> >::type json_t; Then I'd like to be able to write something like this: class vector_assign : public boost::static_visitor<json_t&> { public: vector_assign(int key, const json_t& value); json_t& operator()(int&); json_t& operator()(std::string&); json_t& operator()(vector_t&); private: int key; json_t& value; }; json_t& vector_assign::operator(vector_t& v) { // the canonical case - we assign a value to a slot in the vector if(key>=v.size()) v.reserve(key); v[key] = value; return v; } json_t& map_assign::operator(int& i) { // here we want to discard the int value and convert the variant into a new vector with a single value - but how? } Thanks, - James Jones Administrative Data Mgmt. (v)732-510-1806 375 Raritan Center Pkwy, Suite A (f)732-510-1855 Edison, NJ 08837