linq-select-with-tuples.cs

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

namespace linq_select
{
	public class Holder
	{
		public object arg1 { get; set; }
		public object arg2 { get; set; }

		public Holder(object arg1, object arg2)
		{
			Console.WriteLine($"ctor: {arg1}, {arg2}");
			this.arg1 = arg1;
			this.arg2 = arg2;
		}

		public override string ToString()
			=> $"Holder({arg1}, {arg2})";
	}

    class Program
    {
		static IEnumerable<(string, int)> Data()
		{
			yield return ("a", 1);
			yield return ("b", 2);
			yield return ("c", 3);
		}

        static void Main(string[] args)
        {
			var data = Data();
			var newData = data.Select((s, i) => {
					Console.WriteLine($"got: {s}, {i}");
					return new Holder(s, i);
					});
			Console.WriteLine("--");
			foreach (object item in newData)
				Console.WriteLine(item);
        }
    }
}