C++ How to dispatch to different template function by tag -


there's lots of template functions called f1,f2,f3…

how dispatch runtime-known int different template functions?

of course can use switch that, every time add more template functions or delete template functions, have modify switch again , again. how can in more elegant way?

templates not real-exsited functions can't make std::map of functions pointers.

template<typename t> std::optional<t> f1(){...}  template<typename t> std::optional<t> f2(){...}  template<typename t> std::optional<t> f3(){...}  template<typename t> std::optional<t> f4(){...}  template<typename t> auto dispatch(int tag){      switch(i){     case 1: return f1<t>();     case 2: return f2<t>();     case 3: return f3<t>();     case 4: return f4<t>();     }// have modify these if add or delete template functions  }

here explanation command pattern, guess looking for.

there no templated functions, rewrote it. not doing purpose (convert numbers) can choose function want call , templated.

#include <iostream> #include <string> #include <bitset> #include <sstream> #include <map> #include <cctype>  template <typename t> class converter { public:     virtual std::string convert(t) = 0;     virtual ~converter() {} };  template <typename t> class hex_converter : public converter<t> { public:     std::string convert(t i)     {         return "h: " + i;     } };  template <typename t> class oct_converter : public converter<t> { public:     std::string convert(t i)     {         return  "o: " + i;     } };  template <typename t> class bin_converter : public converter<t> { public:     std::string convert(t i)     {         return "b: " + i;     }  };   class dictionary {     std::map<char, converter<std::string>*> dict;  public:     dictionary()     {         dict.insert( std::make_pair( 'b', new bin_converter<std::string> ) );         dict.insert( std::make_pair( 'o', new oct_converter<std::string> ) );         dict.insert( std::make_pair( 'h', new hex_converter<std::string> ) );     }      converter<std::string>* lookup(char x)     {         std::map<char, converter<std::string>*>::const_iterator iter;         iter = dict.find( toupper(x) );          if( iter != dict.end() )             return iter->second;         else             return null;     }      ~dictionary()     {         while( dict.begin() != dict.end() )         {             delete dict.begin()->second;             dict.erase( dict.begin() );         }     } };  int main() {     using namespace std;     char ch = 'h';     string output = "";     dictionary dict;      converter<std::string>* con = dict.lookup( ch );      if( con != null )         output = con->convert( "test" );     else         output = "invalid";      cout << "result: " << output; }

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