using System;

​

namespace ConsoleApplication

{

    public static class Program

    {

        public static void Main ()

        {

            Settings.Current = new Settings{ ImportantData = "blah blah blah"};

        }

    }

}

​

public class Settings

{

   private static Settings _current;

   private static readonly object _lock = new object();

​

   public static Settings Current

   {

      get

      {

         lock(_lock)

         {

            if (_current == null) throw new InvalidOperationException("Settings uninitialized");

            return _current;

         }

      }

      set

      {

          if (value == null) throw new ArgumentNullException();

          if (_current != null) throw new InvalidOperationException("Current settings can only be set once.");

​

          if (_current == null)

          {

              lock(_lock)

              {

                 if (_current == null) _current = value;

              }

          }

      }

   }

​

​

   public string ImportantData { get; private set; }

​

   // etc. 

}