装饰者模式

    public abstract class Clothes
    {
         public string Look = "beautiful";

        public string Getlook()
        {
            return Look;
        }

        public abstract double Cost();
    }

    public abstract class Dress : Clothes
    {
        public  abstract string WithWho();
    }

    public class Lap : Clothes
    {
        public Lap ()
        {
            Look = "more beautiful with lap";
        }

        public override double Cost()
        {
            return 100;
        }
    }
    public class Pants : Clothes
    {
        public Pants ()
        {
            Look = "more beautiful with pants";
        }

        public override double Cost()
        {
            return 88;
        }
    }

    public class Bag : Dress
    {
        public Clothes Clothes;

        public Bag(Clothes clothes)
        {
            Clothes = clothes;
            Look = Clothes.Getlook() +WithWho()+ " bag";
        }

        public override sealed string WithWho()
        {
            return "need";
        }

        public override double Cost()
        {
            return 10 + Clothes.Cost();
        }
    }

        static void Main(string[] args)
        {
            Clothes clothes=new Lap();
            Console.WriteLine(clothes.Getlook()+" need "+clothes.Cost());
            Clothes clothes2=new Pants();
            clothes2=new Bag(clothes2);
            clothes2=new Bag(clothes2);
            Console.WriteLine(clothes2.Getlook() + " need " + clothes2.Cost());
            Console.ReadLine();
        }