kosanmil

using System.Collections.Generic;

public class House
{
    public List<Room> Rooms;

    public void AcceptVisitor(IVisitor visitor)
    {
        //The handyman will perform checks on this house 
        //(e.g. check the outside walls)

kosanmil

public abstract class Unit 
{
    public string Name;
    public State State;

    public abstract void AcceptVisitor(IVisitor visitor);
}

public class ProcessUnit : Unit 
{

kosanmil

public interface IVisitor
{
    void VisitProcessUnit(ProcessUnit unit);

    void VisitAgentUnit(AgentUnit unit);
}

kosanmil

public class StartUnitVisitor : IVisitor 
{
    public void VisitProcessUnit(ProcessUnit unit) 
    {
        foreach (var childUnit in unit.ChildUnits)
                childUnit.AcceptVisitor(this);
    }

    public void VisitAgentUnit(AgentUnit unit) 
    {

kosanmil

var visitor = new StartUnitVisitor();
processUnitToStart.AcceptVisitor(visitor);

Console.WriteLine("Process unit {0} started", processUnitToStart);