mono/tests/interface.cs

   1 using System;
   2
   3 namespace Obj {
   4         interface Measurable {
   5                 double Area ();
   6         };
   7         class Obj : Measurable {
   8                 public double Area () {
   9                         return 0.0;
  10                 }
  11         };
  12         class Rect : Obj {
  13                 int x, y, w, h;
  14                 public Rect (int vx, int vy, int vw, int vh) {
  15                         x = vx;
  16                         y = vy;
  17                         w = vw;
  18                         h = vh;
  19                 }
  20                 public new double Area () {
  21                         return (double)w*h;
  22                 }
  23         }
  24         class Circle : Obj {
  25                 int x, y, r;
  26                 public Circle (int vx, int vy, int vr) {
  27                         x = vx;
  28                         y = vy;
  29                         r = vr;
  30                 }
  31                 public new double Area () {
  32                         return r*r*System.Math.PI;
  33                 }
  34         }
  35         class Test {
  36                 static public int Main () {
  37                         Obj rect, circle;
  38                         double sum;
  39                         rect = new Rect (0, 0, 10, 20);
  40                         circle = new Circle (0, 0, 20);
  41                         sum = rect.Area() + circle.Area ();
  42                         /* surprise! this calls Obj.Area... */
  43                         if (sum != 0.0)
  44                                 return 1;
  45                         /* now call the derived methods */
  46                         sum = ((Rect)rect).Area() + ((Circle)circle).Area ();
  47                         if (sum != (200 + 400*System.Math.PI))
  48                                 return 2;
  49                         /* let's try to cast to the interface, instead */
  50                         sum = ((Measurable)rect).Area() + ((Measurable)circle).Area ();
  51                         if (sum != 0.0)
  52                                 return 3;
  53                         return 0;
  54                 }
  55         };
  56 };