Question

I want to have a map that has a homogeneous key type but heterogeneous data types.

I want to be able to do something like (pseudo-code):

boost::map<std::string, magic_goes_here> m; m.add<int>('a', 2); m.add<std::string>('b', 'black sheep');  int i = m.get<int>('a'); int j = m.get<int>('b'); // error! 

I could have a pointer to a base class as the data type but would rather not.

I’ve never used boost before but have looked at the fusion library but can’t figure out what I need to do.

Thanks for your help.

Answer 1

#include <map> #include <string> #include <iostream> #include <boost/any.hpp>  int main() {     try     {         std::map<std::string, boost::any> m;         m['a']  = 2;         m['b']  = static_cast<char const *>('black sheep');          int i = boost::any_cast<int>(m['a']);         std::cout << 'I(' << i << ')\n';          int j = boost::any_cast<int>(m['b']); // throws exception         std::cout << 'J(' << j << ')\n';     }     catch(...)     {         std::cout << 'Exception\n';     }  }