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Program 6

// A new example.
// In this file we parameterize individual Point functions with a policy.
// Compile time parametrization of functions - an alternative to passing function objects at run time.

#include <iostream>
#include <string>
#include "point.h"
#include "norms.cc"

// distance_to and less_than as template functions: 
template<typename N> double distance_to(const Point& p, const Point& q){
  return N::distance_to(p,q);
}

template<typename N> bool less_than(const Point& p, const Point& q){
    return N::less_than(p,q);
}

int main(){
  using namespace std;
  double dist;

  Point p1(1,2),
        p2(4,11);
  dist = distance_to<HorizontalNorm>(p1,p2);                       // Parameterizing distance_to with a
  cout << "Distance: " << dist << endl;                            // bundle of two functions from HorizontalNorm
  cout << "Less than? " << 
       (less_than<HorizontalNorm>(p1,p2) ? "true" : "false") <<    // Ditto less_than
       endl << endl;   

  Point p3(1,2),                               
        p4(4,11);
  dist = distance_to<Norm>(p1,p2);                                 // Ditto - here parameterizing with Norm
  cout << "Distance: " << dist << endl; 
  cout << "Less than? " << (less_than<Norm>(p1,p2) ? "true" : "false") << endl << endl;

}