CSharp Indexers

• Allows an instance of an Class or Structs to be indexed just like an array
• Indexers do not have a name and are created using the this[] keyword and has similar syntax to properties

using System;
using System.Collections.Generic;
 
namespace Indexer
{
    public class HttpCookie
    {
        private readonly Dictionary<string, string> _dictionary;
        public DateTime Expiry { get; set; }
 
        public HttpCookie()
        {
            _dictionary = new Dictionary<string, string>();
        }
 
        public string this[string key]
        {
            get { return _dictionary[key]; }
            set { _dictionary[key] = value; }
        }
    }
 
    class Program
    {
        static void Main(string[] args)
        {
            var cookie = new HttpCookie();
            cookie["name"] = "David";
            Console.WriteLine(cookie["name"]);
        }
    }
}

Enumerable

The GetEnumerate() method is used to return an read-only copy of an Collection that can be used to iterate over objects without having to expose the actual collection

public class Workflow
{
    private readonly IList<IActivity> _workflow;
 
    public Workflow()
    {
        _workflow = new List<IActivity>();
    }
 
    public void Add(IActivity activity)
    {
        _workflow.Add(activity);
    }
		
    public IEnumerable<IActivity> GetActivities()
    {
        return _workflow;
    }
}

Indexers - C# Programming Guide | Microsoft Docs

Indexers in C#

C# | Get an enumerator that iterates through the List - GeeksforGeeks