templated_point.cc

#include <iostream>
#include "math.h"

template<int n> class Field {};

template<typename B, typename T>
class Member : public B {
 public:
  Member(T initial) { value_ = initial; }
  T value() { return value_; }
 private:
  T value_;
};

template<typename T>
class Squared {
 public:
  static double compute(T v) { return v * v; }
};

template<typename T>
class Sqrt {
 public:
  static double compute(T v) { return sqrt(v); }
};

class Point :
    public Member<Field<0>, int>,
    public Member<Field<1>, int>
{
 public:
  Point(int x, int y) : Member<Field<0>, int>(x),
                        Member<Field<1>, int>(y) {}
  int magnitude() {
    return Sqrt<int>::compute(
        Squared<int>::compute(Member<Field<0>,int>::value()) +
        Squared<int>::compute(Member<Field<1>,int>::value()));
  }
};

int main(void) {
  Point p(3, 4);
  std::cout << "Magnitude is " << p.magnitude() << "\n";
}