扩展属性应用

字段去除空格

代码

 [AttributeUsage(AttributeTargets.Property,Inherited=false,AllowMultiple=false)]
    public  class TrimAttribute:Attribute
    { private readonly Type type;
    public TrimAttribute(Type type)
    {
        this.type = type;
    }
    public Type Type
    {
        get { return this.type; }
    }
    }
  public static class TrimAttributeExtension
  {   
      public static void Trim(this Object obj)
      {
          Type t = obj.GetType();
          foreach(var prop in t.GetProperties())
          { 
            foreach(var attr in prop.GetCustomAttributes(typeof(TrimAttribute),true))
            {
                TrimAttribute tsa = (TrimAttribute)attr;
                if(prop.GetValue(obj,null)!=null&&(tsa.Type==typeof(string)))
                {
                    prop.SetValue(obj,GetPropertyValue(obj,prop.Name).ToString().Trim(),null);
                }
            }
          }
      }
      private static object GetPropertyValue(object instance,string PropertName)
      {
          return instance.GetType().InvokeMember(PropertName,System.Reflection.BindingFlags.GetProperty,null,instance,new Object[]{});
      }
  }

使用

  public class SomeClass
  {   [Trim(typeof(string))]
      string Name { get; set; }
  }

查询语法

 public  class SelectClass
    {
        public void Method1()
        { 
         int[] fool=new int[100];
         for (int num = 0; num < fool.Length; num++)
         {
             fool[num] = num * num;
         }
         foreach(int i in fool)
         {
             Console.WriteLine(i.ToString());
         }
        }
        public void Method1Select()
        {
            int[] fool = (from n in Enumerable.Range(0, 100) select n * n).ToArray();
            fool.ForAll((n) => Console.WriteLine(n));
        }
        public IEnumerable<Tuple<int, int>> ProduceIndices()
        {
            for (int x = 0; x < 100; x++)
                for (int y = 0; y < 100; y++)
                    if (x + y < 100)
                        yield return Tuple.Create(x,y);
        }
        public IEnumerable<Tuple<int, int>> ProduceIndicesSelect()
        {
            return from x in Enumerable.Range(0, 100)
                   from y in Enumerable.Range(0, 100)
                   where x + y < 100
                   select Tuple.Create(x,y);
        }
    }

    public static class Extensions
    {
        public static void ForAll<T>(this IEnumerable<T> sequence, Action<T> action)
        { 
         foreach(T item in sequence)
         {
             action(item);
         }
        }
    }