using System;

​

public class Program

{

    public record DaRecord(string Message, int Value)

    {

        public void Set(string name, object newValue) 

        {

            var prop = typeof(DaRecord).GetProperty(name);

            prop.SetValue(this, newValue);

        }

    }

    public static void Main()

    {

        var a = new DaRecord("Secret", 4);

        var b = a;

        var c = a with {};

        a.Set("Message", "New secret");

        a.Set("Value", 5);

        Console.WriteLine("A: " + a);

        Console.WriteLine("B: " + b);

        Console.WriteLine("C: " + c);

    }

}