using System;

using System.Collections.Generic;

​

​

public static class QuickStart

{

    public delegate double CalculateDelegate(double x, double y);

​

    public class Test

    {        

        public CalculateDelegate calculate;                

    }

​

    public class DelegateContainer

    {

        public double Add(double x, double y)

        {

            return x + y;

        }

        public double Subtract(double x, double y)

        {

            return x - y;

        }

​

        public Dictionary<string, CalculateDelegate> collection = new Dictionary<string, CalculateDelegate>();

        public DelegateContainer()

        {

            collection["Add"] = Add;

            collection["Subtract"] = Subtract;

        }

​

        public CalculateDelegate this[string name]

        {            

            get

            {                

                return collection[name];

            }            

        }

    }

​

    public static void Main()

    {        

        var target = new Test();

        var container = new DelegateContainer();

        target.calculate = container["Add"];

        Console.WriteLine("1 + 2 = " + target.calculate(1, 2));

​

        target.calculate = container["Subtract"];

        Console.WriteLine("5 - 2 = " + target.calculate(5, 2));

    }

​

}