C#动态对象(dynamic)示例(实现方法和属性的动态)

C#的动态对象的属性实现比较简单,如果要实现动态语言那种动态方法就比较困难,因为对于dynamic对象,扩展方法,匿名方法都是不能用直接的,这里还是利用对象和委托来模拟这种动态方法的实现,看起来有点JavaScript的对象味道:

1)定义一个委托,参数个数可变,参数都是object类型:这里的委托多有个dynamic参数,代表调用这个委托的动态对象本身.

     public delegate object MyDelegate(dynamic Sender, params object[] PMs);  

2)定义一个委托转载对象,因为dynamic对象不能直接用匿名方法,这里用对象去承载:

    public class DelegateObj  
    {  
        private MyDelegate _delegate;  
  
        public MyDelegate CallMethod  
        {  
            get { return _delegate; }  
        }  
        private DelegateObj(MyDelegate D)  
        {  
            _delegate = D;  
        }  
        /// <summary>  
        /// 构造委托对象，让它看起来有点javascript定义的味道.  
        /// </summary>  
        /// <param name="D"></param>  
        /// <returns></returns>  
        public static DelegateObj Function(MyDelegate D)  
        {  
            return new DelegateObj(D);  
        }  
    }  

3) 定义一个动态对象:

    public class DynObj : DynamicObject  
    {  
        //保存对象动态定义的属性值  
        private Dictionary<string, object> _values;  
        public DynObj()  
        {  
            _values = new Dictionary<string, object>();  
        }  
        /// <summary>  
        /// 获取属性值  
        /// </summary>  
        /// <param name="propertyName"></param>  
        /// <returns></returns>  
        public object GetPropertyValue(string propertyName)  
        {  
            if (_values.ContainsKey(propertyName) == true)  
            {  
                return _values[propertyName];  
            }  
            return null;  
        }  
        /// <summary>  
        /// 设置属性值  
        /// </summary>  
        /// <param name="propertyName"></param>  
        /// <param name="value"></param>  
        public void SetPropertyValue(string propertyName,object value)  
        {  
            if (_values.ContainsKey(propertyName) == true)  
            {  
                _values[propertyName] = value;  
            }  
            else  
            {  
                _values.Add(propertyName, value);  
            }  
        }  
        /// <summary>  
        /// 实现动态对象属性成员访问的方法，得到返回指定属性的值  
        /// </summary>  
        /// <param name="binder"></param>  
        /// <param name="result"></param>  
        /// <returns></returns>  
        public override bool TryGetMember(GetMemberBinder binder, out object result)  
        {  
            result = GetPropertyValue(binder.Name);  
            return result == null ? false : true;  
        }  
        /// <summary>  
        /// 实现动态对象属性值设置的方法。  
        /// </summary>  
        /// <param name="binder"></param>  
        /// <param name="value"></param>  
        /// <returns></returns>  
        public override bool TrySetMember(SetMemberBinder binder, object value)  
        {  
            SetPropertyValue(binder.Name, value);  
            return true;  
        }  
        /// <summary>  
        /// 动态对象动态方法调用时执行的实际代码  
        /// </summary>  
        /// <param name="binder"></param>  
        /// <param name="args"></param>  
        /// <param name="result"></param>  
        /// <returns></returns>  
        public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result)  
        {  
            var theDelegateObj = GetPropertyValue(binder.Name) as DelegateObj;  
            if (theDelegateObj == null || theDelegateObj.CallMethod == null)  
            {  
                result = null;  
                return false;  
            }  
            result = theDelegateObj.CallMethod(this,args);  
            return true;  
        }  
        public override bool TryInvoke(InvokeBinder binder, object[] args, out object result)  
        {  
            return base.TryInvoke(binder, args, out result);  
        }  
    }  

测试代码：

           dynamic theObj = new DynObj();  
           theObj.aaa = "this is a test";//动态属性  
           //动态方法，这里不能没法定义参数，调用的时候可以是任意多参数，具体参数类型和含义就只能自己去小心处理了.  
           theObj.show = DelegateObj.Function((s, pms) =>  
           {  
               if (pms != null && pms.Length > 0)  
               {  
                   MessageBox.Show(pms[0].ToString() + ":" + s.aaa);  
               }  
               else  
               {  
                   MessageBox.Show(s.aaa);  
               }  
               return null;  
           }  
           );  
           theObj.show("hello");