static void CalculateArea(IAmVisitable visitable)
{
var visitor = new AreaCalculationVisitor();
visitable.Accept(visitor);
Console.WriteLine("{0} area: {1}", visitable.GetType().Name, visitor.Area);
}
static void CalculateDrawingArea(IAmVisitable visitable)
{
var visitor = new DrawingAreaCalculationVisitor();
visitable.Accept(visitor);
var rect = visitor.Rect;
Console.WriteLine("Drawing area for {0}: ({1},{2}) ({3},{4})", visitable.GetType().Name, rect.Left, rect.Top, rect.Right, rect.Bottom);
}