The following code example is taken from the book
C++ Templates - The Complete Guide
by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002
© Copyright David Vandevoorde and Nicolai M. Josuttis 2002
#include "duo1.hpp"
#include "duo2.hpp"
#include "duo3.hpp"
#include "duo4.hpp"
#include "duo5.hpp"
#include <iostream>
int main()
{
// create and use simple duo
Duo<bool,int> d;
std::cout << d.v1() << std::endl;
std::cout << val<1>(d) << std::endl;
// create and use triple
Duo<bool,Duo<int,float> > t;
val<1>(t) = true;
val<2>(t) = 42;
val<3>(t) = 0.2;
std::cout << val<1>(t) << std::endl;
std::cout << val<2>(t) << std::endl;
std::cout << val<3>(t) << std::endl;
}