C#依頼とイベントの簡単な応用

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;



namespace TestIO

{

    public delegate double PriceHandler();



    public class PriceManager

    {

        public PriceHandler GetPriceHandler;



        // ， 100 8.8 ，  

        public double GetPrice()

        {

            //GetPriceHandler.GetInvocationList();  , 

            if (GetPriceHandler.GetInvocationList().Count() > 0)

            {

                if (GetPriceHandler() > 100)

                    return GetPriceHandler() * 0.88;

                else

                    return GetPriceHandler();

            }

            return -1;

        }

    }



    class Program

    {

        static void Main(string[] args)

        {

            PriceManager priceManager = new PriceManager();



            // priceManager GetPrice  

            // Invoke ，  



            priceManager.GetPriceHandler = new PriceHandler(ComputerPrice);

            Console.WriteLine(string.Format("GetPrice
  Computer's price is {0}!",

                priceManager.GetPrice()));

            //priceManager.GetPrice();

            Console.WriteLine(string.Format("Invoke
  Computer's price is {0}!",

                priceManager.GetPriceHandler.Invoke()));



            Console.WriteLine();



            priceManager.GetPriceHandler = new PriceHandler(BookPrice);

            Console.WriteLine(string.Format("GetPrice
  Book's price is {0}!",

                priceManager.GetPrice()));

            Console.WriteLine(string.Format("Invoke
  Book's price is {0}!",

                priceManager.GetPriceHandler.Invoke()));



            Console.ReadKey();

        }

        // 98  

        public static double BookPrice()

        {

            return 98.0;

        }

        // 8800  

        public static double ComputerPrice()

        {

            return 8800.0;

        }

    } 









}