直接贴代码，注意里面string.Join这个方法以前没注意，不错，不过4.0才支持ienumber类型，3.5之下运行会报错，看来4.0更加成熟点

public class ErrorEntity    {        IList
     
       messages = new List
      
       ();        public static ErrorEntity operator +(ErrorEntity entity, string message)        {            entity.messages.Add(message);            return entity;        }        public IList
       
         Messages { get { return messages; } }    }
       
      
     

/// 
    ///这是 ErrorEntityTest 的测试类，旨在    ///包含所有 ErrorEntityTest 单元测试    ///
    [TestClass()]    public class ErrorEntityTest    {        [TestMethod]        public void test()        {            var entity = new ErrorEntity.ErrorEntity();            entity += "用户名不能为空";            entity += "密码不能为空";            Trace.WriteLine(string.Join("\n", entity.Messages));        }    }