Private class data pattern

 public class Circle
 {
   private double radius;
   private Color color;
   private Point origin;
   public Circle(double radius, Color color, Point origin)
   {
     this.radius = radius;
     this.color = color;
     this.origin = origin;
   }
   public double Circumference
   {
     get { return 2 * Math.PI * this.radius; }
   }
   public double Diameter
   {
     get { return 2 * this.radius; }
   }
   public void Draw(Graphics graphics)
   {
     //...
   }
 }