SE450: Double Dispatch [43/55]

• Each element type provides methods:
  public class ElementType_i
  {
     public void accept(Visitor v) { v.visitElementType_i(this); }
     ...
  }
• Completely mechanical
• Example:
  public class DirectoryNode
  {
     public void accept(Visitor v) { v.visitDirectoryNode(this); }
     ...
  }