1.1 --- a/Hardware/Hardware.cs	Thu Aug 12 20:53:27 2010 +0000
     1.2 +++ b/Hardware/Hardware.cs	Sun Aug 15 14:46:58 2010 +0000
     1.3 @@ -80,8 +80,9 @@
     1.4      public abstract void Update();
     1.5  
     1.6      public void Accept(IVisitor visitor) {
     1.7 -      if (visitor != null)
     1.8 -        visitor.VisitHardware(this);
     1.9 +      if (visitor == null)
    1.10 +        throw new ArgumentNullException("visitor");
    1.11 +      visitor.VisitHardware(this);
    1.12      }
    1.13  
    1.14      public void Traverse(IVisitor visitor) {