// Same example programmed with unique_ptr

#include <memory>
#include <iostream>
#include <string>
#include "point.h"

using namespace std;

void f(Point *pp1){
  unique_ptr<Point>ap1(pp1),
                   ap2(new Point(3,4));

  // Use unique_ptr<Point> in the same way as Point* is used:
  cout << "ap1: " << *ap1 << endl;   // (1,2)
  cout << "ap2: " << *ap2 << endl;   // (3,4)

  ap2->displace(1,1);
  cout << "ap2: " << *ap2 << endl;   // (4,5)

  cout << "ap1-ap2 dist: " << ap1->distance_to(*ap2) << endl;  // 4.24264

  // Destructive copying:  The point referred by ap2 is deleted.
  //                       The pointer encapsualated in ap1 is moved to ap2.
  //                       ap1 is unbound (becomes nullptr).
  cout << "Now assigning ap1 to ap2" << endl;
  ap2 = move(ap1);         // Short form or  ap2 = static_cast<unique_ptr<Point>&&>(ap1);

  if (ap1.get())                        // ap1 is nullptr
     cout << "ap1: " << *ap1 << endl;  
  else
     cout << "ap1 is nullptr" << endl;

  if (ap2.get())                        // (1,2)
     cout << "ap2: " << *ap2 << endl;
  else
     cout << "ap2 is nullptr" << endl;

  // ap1 and ap2 are deleted on exit from f - out of scope.
}

int main(){
  Point *p = new Point(1,2);   // Better to make a smart pointer here, and pass it to p. 
  f(p);                        // See the exercise!

  cout << "p: " << *p << endl; // Unsafe! 
                               // p has been deleted by exit from f.
}