// Illustrates constness, in particular in relation to pointers. DOES NOT COMPILE.

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

int main(){
  Point p(1,2);             // p is a Point. It can be moved (by mutation).
  p.move(0,1);

  const Point q(3,4);       // q is a constant point.
  q.move(1,2);              // ERROR (compile time)

  const Point *r = &p;      // r is pointer to a constant point
  r->move(1,2);             // ERROR (compile time)

  Point const *rr = &p;     // rr is pointer to a constant Point - fully equivalent to definition or r above.

  Point *const s = &p;      // s is a constant pointer to 'the point p'. *const is a 'declarator operator'.
  s->move(1,2);             // OK.
  s = nullptr;              // ERROR: Assignment of read-only variable s. (Compile time)

  const Point *const t= &p; // t is a constant pointer to a constant point.
  t->move(1,2);             // ERROR (compile time)
  t = nullptr;              // ERROR (compile time)

  Point const *const v= &p; // Same as definition of t (Point and const has just been reversed). 
}