using System;

namespace Test
{
	public class A 
	{
	    public string Info { get; set; }
	    /* much more data */
	}
	
	public class B
	{
	    private A m_instanceOfA;
	
	    public B(A a) { m_instanceOfA = a; }
	
	    public string Info
	    {
	    	get { return m_instanceOfA.Info; }
	    	set { m_instanceOfA.Info = value; }
	    }
	
	    // requires an instance of a private object, this establishes our pseudo-friendship
	    internal A GetInstanceOfA(C.AGetter getter) { return getter.Get(m_instanceOfA); }
	
	    /* And some more data of its own*/
	}
	
	public class C
	{
	    private A m_instanceOfA;
	
	    private static AGetter m_AGetter; // initialized before first use; not visible outside of C
	
	    // class needs to be visible to B, actual instance does not (we call b.GetInstanceOfA from C)
	    internal class AGetter
	    {
	        static AGetter() { m_AGetter = new AGetter(); } // initialize singleton
	
	        private AGetter() { } // disallow instantiation except our private singleton in C
	
	        public A Get(A a) { return a; } // force a NullReferenceException if calling b.GetInstanceOfA(null)
	    }
	    
	    static C()
	    {
	    	// ensure that m_AGetter is initialized
	    	System.Runtime.CompilerServices.RuntimeHelpers.RunClassConstructor(typeof(AGetter).TypeHandle);
	    }
	
	    public C(B b)
	    {
	    	m_instanceOfA = b.GetInstanceOfA(m_AGetter);
	    }
	    
	    public string Info
	    {
	    	get { return m_instanceOfA.Info; }
	    	set { m_instanceOfA.Info = value; }
	    }
	
	    /* And some more data of its own*/
	}
	
	public class Test
	{
		public static void Main()
		{
			A a = new A();
			B b = new B(a);
			C c = new C(b);
			c.Info = "Hello World!";
			Console.WriteLine(a.Info);
		}
	}
}