using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApplication1
{
    public class DataManager
    {
        public static MyClassManager MyClass { get { return MyClassManager.Instance; } }
    }



    /* 1단계 */

    public class MyClassManager
    {
        private List<MyClass> myList = new List<MyClass>();

        private static MyClassManager instance = null;

        private MyClassManager() { }

        public static MyClassManager Instance
        {
            get
            {
                if (instance == null)
                    instance = new MyClassManager();

                return instance;
            }
        }

        public void Add(int a, int b)
        {
            myList.Add(new MyClass(a, b));
        }

        public void RemoveAt(int index)
        {
            myList.RemoveAt(index);
        }

        public MyClass ElementAt(int index)
        {
            return myList.ElementAt(index);
        }

        public int Length
        {
            get
            {
                return myList.Count;
            }
        }
    }

    public class MyClass
    {
        public SubClassManager myCustomList = new SubClassManager();


        public int a, b;

        public MyClass(int a, int b)
        {
            this.a = a;
            this.b = b;

        }
    }



    /* 2단계 - 마치 List처럼 전체 재정의 */

    public class SubClassManager
    {
        /* Singleton 사용X */
        private List<SubClass> myList = new List<SubClass>();

        public void Add(int x, int y)
        {
            myList.Add(new SubClass(x, y));
        }

        public SubClass this[int index]
        {
            get
            {
                return myList[index];
            }
            set
            {
                myList[index] = value;
            }
        }
    }

    public class SubClass
    {
        public SubClass(int x, int y)
        {
            this.x = x;
            this.y = y;
        }


        public int x { get; set; }
        public int y { get; set; }
    }
}