using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        Random rand = new Random();

        var names = "Bob,Biff,Bill".Split(',').Select(x=>x.Trim()).ToList();

        var myList = new MyList<Person>();

        myList.AddRange(names.Select(x=>new Person{Name = x, Age = rand.Next(20, 30)}));

        foreach(var item in myList){

            Console.WriteLine(item.Name + " " + item.Age);

        }

        using(var enumerator = myList.GetIndexedEnumerator()){

            while(enumerator.MoveNext()){

                var person = enumerator.Current;

                Console.WriteLine("["+enumerator.Index+ "] "+person.Name+" "+person.Age);

            }

        }

    }

}

​

public class Person{

    public string Name{get;set;}

    public int Age{get;set;}

}

​

public class MyList<T> : List<T>{

    public new IEnumerator<T> GetEnumerator(){

        return new IndexedEnumerator<T>(base.GetEnumerator());

    }

}

​

public static class Helpers{

    public static IndexedEnumerator<T> GetIndexedEnumerator<T>(this IEnumerable<T> list){

        return new IndexedEnumerator<T>(list.GetEnumerator());

    }

}

​

public class BaseEnumerator<T> : IEnumerator<T>{

    public BaseEnumerator(IEnumerator<T> enumer){

        enumerator = enumer;

    }

    protected virtual IEnumerator<T> enumerator{get;set;}

    protected virtual T current {get;set;}

    public virtual bool MoveNext(){

        return enumerator.MoveNext();

    }

    public virtual IEnumerator<T> GetEnumerator(){

        return enumerator;

    }

    public virtual T Current {get{return enumerator.Current;}}

    object IEnumerator.Current {get{return enumerator.Current;}}

    public virtual void Reset(){}

    public virtual void Dispose(){}

}

​

public class IndexedEnumerator<T> : BaseEnumerator<T>

{

    public IndexedEnumerator(IEnumerator<T> enumer):base(enumer){

    }

    public int Index {get; private set;}

    public override bool MoveNext(){

        Console.WriteLine("\tIndexedEnumerator, MoveNext was called");

        Index++;

        return enumerator.MoveNext();

    }

}