CRTP: curiously recurring template pattern

crtp.cpp

#include <iostream>

template<typename T>
struct inequality {
  bool operator!=(const T& that) {
    return !(static_cast<const T&>(*this) == that);
  }
};

// mutual dependence of inequality and point
// derived class inherit from a base class templatized with the derived class
// --- it does make my head hurt ! ---
class point : public inequality<point> {
 public:
  point(int x, int y) : x(x), y(y) {};
  bool operator==(const point& that) const {
    return (x == that.x && y == that.y);
  };
  
 private:
  int x, y;
};

int main() {

  // CTRP: curiously recurring template pattern
  point p1(3, 4), p2(3, 5);
  if (p1 != p2) {
    std::cout << "pt 1 doesn't equal to pt 2" << std::endl;
  }
  
  return 0;

}