public class ItemCache
    {
        private static Hashtable cacheTable = new Hashtable();
        public static Item GetItem( string filename )
        {
            lock( typeof(ItemCache) )
            {
                if( cacheTable.ContainsKey(filename.ToLower()) )
                {
                    return (Item)cacheTable[filename.ToLower()];
                }
                Item item = new Item(filename);
                cacheTable.Add(filename.ToLower(),item);
                return item;
            }
        }
        private ItemCache()
        {
        }
    }