Is there an elegant way to represent a map containing different types in C++? -

i'm building class want configure using various parameters may 1 of: int, double , string (or const char * matter). in language ruby, build initialization function takes hash keyed string. example:

class example   def init_with_params params     puts params   end end  e = example.new e.init_with_params({ "outputfile" => "/tmp/out.txt", "capturefps" => 25.0, "retrydelayseconds" => 5 }) 

how can create similar behavior in c++?

looking around found several posts talking boost::variant. rather avoid using boost if limiting different types 3 types mentioned above rather clean solution can made.

edit: agree using designed , tested code such boost.variant better re-implementing same idea. in case, problem reduced using 3 basic types, looking simplest possible way of implementing it.

here cut down version of regularly use store program configuration properties, maybe find useful:

#include <map> #include <string> #include <sstream> #include <fstream> #include <iostream> #include <initializer_list>  class config {     // stored internally std::strings     // read configuration file     typedef std::map<std::string, std::string> prop_map;     typedef prop_map::const_iterator prop_map_citer;      prop_map props;  public:     // example constructor. have method read     // values in file     config(std::initializer_list<std::pair<std::string, std::string>> list)     {         for(const auto& p: list)             props[p.first] = p.second;     }      // values converted requested whatever types     // need be. default may given in case value     // missing configuration file     template<typename t>     t get(const std::string& s, const t& dflt = t()) const     {         prop_map_citer found = props.find(s);          if(found == props.end())             return dflt;          t t;         std::istringstream(found->second) >> std::boolalpha >> t;         return t;     }      // std::strings need special handling (no conversion)     std::string get(const std::string& s, const std::string& dflt = "") const     {         prop_map_citer found = props.find(s);         return found != props.end() ? found->second : dflt;     }  };  int main() {     const config cfg =     {         {"outputfile", "/tmp/out.txt"}         , {"capturefps", "25.0"}         , {"retrydelayseconds", "5"}     };      std::string s;     float f;     int i;      s = cfg.get("outputfile");     f = cfg.get<float>("capturefps");     = cfg.get<int>("retrydelayseconds");      std::cout << "s: " << s << '\n';     std::cout << "f: " << f << '\n';     std::cout << "i: " << << '\n'; }