dotnet3.5下Singleton辅助类实现

      经常要用到Singleton模式，通常情况下我们是为那个类写一个static method来创建对象。.net3.5下，可以封装这么一个辅助类，
看代码如下：

 1     #region Singleton
 2     /// <summary>
 3     /// Used for classes that are single instances per appdomain
 4     /// </summary>
 5     public static class Singleton
 6     {
 7         private static class Storage<T>
 8         {
 9             internal static T s_instance;
         }
 
         /// <summary>
         /// Gets the instance.
         /// </summary>
         /// <typeparam name="T">Func<T></typeparam>
         /// <param name="op">The op.</param>
         /// <returns>T</returns>
         /// <remark>Author : PetterLiu 2008-12-2816:02  http://wintersun.cnblogs.com </remark>
         public static T GetInstance<T>(Func<T> op)
         {
             if (Storage<T>.s_instance == null)
             {
                 lock (typeof(Storage<T>))
                 {
                     if (Storage<T>.s_instance == null)
                     {
                         T temp = op();
                         System.Threading.Thread.MemoryBarrier();
                         Storage<T>.s_instance = temp;
                     }
                 }
             }
             return Storage<T>.s_instance;
         }
 
         /// <summary>
         /// Gets the instance.
         /// </summary>
         /// <typeparam name="T">T</typeparam>
         /// <returns>T</returns>
         /// <remark>Author : PetterLiu 2008-12-2816:02  http://wintersun.cnblogs.com </remark>
         public static T GetInstance<T>()
             where T : new()
         {
             return GetInstance(() => new T());
         }
     }
     #endregion

UnitTest:

 1         /// <summary>
 2         /// Commons the test.
 3         /// </summary>
 4         /// <remark>Author : PetterLiu 2008-12-2816:04  http://wintersun.cnblogs.com </remark>
 5         [TestMethod]
 6         public void CommonTest()
 7         {
 8             Pipe pipe1 = Singleton.GetInstance<Pipe>();
 9             Pipe pipe2 = Singleton.GetInstance<Pipe>();
             Assert.AreSame(pipe1, pipe2);
         }
 
 
         /// <summary>
         /// Anonymouses this instance.
         /// </summary>
         /// <remark>Author : PetterLiu 2008-12-2816:04  http://wintersun.cnblogs.com </remark>
         [TestMethod]
         public void Anonymous()
         {
             Pipe pipe1 = Singleton.GetInstance<Pipe>(delegate() { return new Pipe();});
             Pipe pipe2 = Singleton.GetInstance<Pipe>(delegate() { return new Pipe(); });
             Assert.AreSame(pipe1,pipe2);
         }
 
         /// <summary>
         /// Usings the lambda.
         /// </summary>
         /// <remark>Author : PetterLiu 2008-12-2816:04  http://wintersun.cnblogs.com </remark>
         [TestMethod]
         public void UsingLambda()
         {
             Pipe pipe1 = Singleton.GetInstance<Pipe>(() => new Pipe());
             Pipe pipe2 = Singleton.GetInstance<Pipe>(() => new Pipe());
             Assert.AreSame(pipe1, pipe2);
         }

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