using System;

using System.Linq;

using System.Collections.Generic;       

​

public class Program

{

    public interface IColorProvider

    {

        string GetName();

    }

    public class ColorProvider : IColorProvider

    {

        private string _name = "blue";

        public void SetName(string name) { _name = name; }

        public string GetName() { return _name; }

    }

​

    public abstract class Cup

    {

        private readonly IColorProvider _colorProvider;

        protected Cup(IColorProvider colorProvider)

        {

            _colorProvider = colorProvider;

        }

​

        public string ColorName { 

            get => _colorProvider.GetName(); 

        }

    }

​

    public class TeaCup : Cup

    {

        public TeaCup() : base(null) { }

        public TeaCup(IColorProvider colorProvider) : base(colorProvider) { }

    }

​

    public class CoffeeCup : Cup

    {

        public CoffeeCup() : base(null) { }

        public CoffeeCup(IColorProvider colorProvider) : base(colorProvider) { }

    }

​

    private static void Main(string[] args)

    {

        var colorProvider = new ColorProvider();

        var cup1 = new TeaCup(colorProvider);

        var cup2 = new CoffeeCup(colorProvider);

​

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

        colorProvider.SetName( "red");

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

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

​

        colorProvider.SetName( "green");

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

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

    }

}