Some immutability stuff for informatorbloggen

ImmutableList[T].cs

public class ImmutableList<T> : IEnumerable<T>
{
   List<T> _items;
   
   public ImmutableList()
   {
      _items = new List<T>();
   }
   
   private ImmutableList(List<T> items)
   {
      _items = items;
   }
   
   public ImmutableList<T> Add(T item)
   {
       var newItems = _items.ToList();
     newItems.Add(item);
	   return new ImmutableList<T>(newItems);
   }
   
   public int Count{get{return _items.Count;}}
   
   public IEnumerator<T> GetEnumerator()
   {
      foreach(T item in _items) yield return item;
   }

   IEnumerator IEnumerable.GetEnumerator()
   {
       return GetEnumerator();
   }
}