#include <iostream>
#include <functional>
#include <map>
#include <string>

class A
{
        public:
                A(): i_(10) {}
                ~A() {}

                void set(int i) { i_ = i; }
                int get_i() const { return i_; }
        private:
                int i_;
};


int main(int argc, char** argv)
{
    std::map<std::string, std::reference_wrapper<const A>> map;
    A a;
    map.emplace(std::make_pair(std::string("a"), std::ref<const A>(a)));

   auto a1 = map.at("a").get();
   a1.set(11);

   std::cout << a1.get_i() << " " << a.get_i() << std::endl;

   return 0;

}