1.1 --- a/Hardware/SensorVisitor.cs	Thu Aug 12 20:53:27 2010 +0000
     1.2 +++ b/Hardware/SensorVisitor.cs	Sun Aug 15 14:46:58 2010 +0000
     1.3 @@ -45,14 +45,20 @@
     1.4      private SensorEventHandler handler;
     1.5  
     1.6      public SensorVisitor(SensorEventHandler handler) {
     1.7 +      if (handler == null)
     1.8 +        throw new ArgumentNullException("handler");
     1.9        this.handler = handler;
    1.10      }
    1.11  
    1.12      public void VisitComputer(IComputer computer) {
    1.13 +      if (computer == null)
    1.14 +        throw new ArgumentNullException("computer");
    1.15        computer.Traverse(this);
    1.16      }
    1.17  
    1.18      public void VisitHardware(IHardware hardware) {
    1.19 +      if (hardware == null)
    1.20 +        throw new ArgumentNullException("hardware");
    1.21        hardware.Traverse(this);
    1.22      }
    1.23