using System;

using System.Linq;

using System.Collections.Generic;       

​

public class Program

{

    public class Color

    {

        public string Name { get;set; } = "blue";

    }

​

    public abstract class Cup

    {

        protected Color Color { get; private set; }

        protected Cup(Color color)

        {

            Color = color;

        }

​

        public string ColorName { 

            get => Color.Name; 

            /// ATTENTION:

            /// This is very bad style

            /// try to avoid setting properties of shared properties

            /// this will lead to errors and is very difficult to 

            /// find in debugging or searching for potential errors

            set => Color.Name = value; 

        }

    }

​

    public class TeaCup : Cup

    {

        public TeaCup() : base(null) { }

​

        public TeaCup(Color color) : base(color) { }

​

    }

​

    public class CoffeeCup : Cup

    {

        public CoffeeCup() : base(null) { }

​

        public CoffeeCup(Color color) : base(color) { }

​

    }

​

    private static void Main(string[] args)

    {

        var color = new Color();

        var cup1 = new TeaCup(color);

        var cup2 = new CoffeeCup(color);

​

        Console.WriteLine("color = {0}", color.Name);

        cup1.ColorName = "red";

        Console.WriteLine("cup1.ColorName = {0}", cup1.ColorName);

        Console.WriteLine("cup2.ColorName = {0}", cup2.ColorName);

​

        cup2.ColorName = "green";

        Console.WriteLine("cup1.ColorName = {0}", cup1.ColorName);

        Console.WriteLine("cup2.ColorName = {0}", cup2.ColorName);

    }

}