using System;

public class Program

{

    public static void Main()

    {

        Factory fc = new Factory();

        IdObj ctrl = new IdObj();

        ctrl.Id = 1;

        User us = new User(ctrl);

        us.PrintFromUser();

        //us.ChangeId();

        ctrl =  new IdObj();

        ctrl.Id = 2;

        us.PrintFromUser();

    }

}

​

public interface IControl

{

}

​

public class IdObj : IControl

{

    public int Id = 0;

    public void Print()

    {

        Console.WriteLine("From IdObj : " + Id);

    }

}

​

public class User

{

    IdObj ob = null;

    public User(IdObj x)

    {

        ob = x ;

    }

    public void ChangeId()

    {

        ob.Id = -1;

    }

    public void PrintFromUser()

    {

        Console.WriteLine("From User: "+ ob.Id);

    }

}

​

public class Factory

{

    public IControl GetIdObj()

    {

        return new IdObj();

    }

}