using System;

using System.Collections.Generic;

public class Program : IPersonVisitor

{

    public static void Main()

    {

        // DoubleDispatch Example

        var persons = new List<IPerson>();

        persons.Add(new NaturalPerson());

        persons.Add(new LegalPerson());

        var p = new Program();

        p.Process(persons);

    }

    public void Process(IEnumerable<IPerson> persons)

    {

        foreach( var person in persons )

        {

            person.Visit(this);

        }

    }

    public void VisitedBy( NaturalPerson p )

    {

        Console.WriteLine("It's a natural person!");

    }

    public void VisitedBy( LegalPerson p )

    {

        Console.WriteLine("It's a legal person!");

    }

}

​

public interface IPerson

{

    void Visit(IPersonVisitor v);

}

​

public class NaturalPerson : IPerson

{

    public void Visit(IPersonVisitor v)

    {

        v.VisitedBy(this);

    }

}

​

public class LegalPerson : IPerson

{

    public void Visit(IPersonVisitor v)

    {

        v.VisitedBy(this);

    }

}

​

public interface IPersonVisitor

{

    void VisitedBy( NaturalPerson p );

    void VisitedBy( LegalPerson p );

}

​