C#動態對象(dynamic)示例(實現方法和屬性的動態)

C#的動態對象的屬性實現比較簡單,如果要實現動態語言那種動態方法就比較困難,因為對於dynamic對象,擴展方法,匿名方法都是不能用直接的,這里還是利用對象和委托來模擬這種動態方法的實現,看起來有點JavaScript的對象味道:

1)定義一個委托,參數個數可變,參數都是object類型:這里的委托多有個dynamic參數,代表調用這個委托的動態對象本身.

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

 

2)定義一個委托轉載對象,因為dynamic對象不能直接用匿名方法,這里用對象去承載:

    public class DelegateObj  
    {  
        private MyDelegate _delegate;  
  
        public MyDelegate CallMethod  
        {  
            get { return _delegate; }  
        }  
        private DelegateObj(MyDelegate D)  
        {  
            _delegate = D;  
        }  
        /// <summary>  
        /// 構造委托對象，讓它看起來有點javascript定義的味道.  
        /// </summary>  
        /// <param name="D"></param>  
        /// <returns></returns>  
        public static DelegateObj Function(MyDelegate D)  
        {  
            return new DelegateObj(D);  
        }  
    }  

 

3) 定義一個動態對象:

    public class DynObj : DynamicObject  
    {  
        //保存對象動態定義的屬性值  
        private Dictionary<string, object> _values;  
        public DynObj()  
        {  
            _values = new Dictionary<string, object>();  
        }  
        /// <summary>  
        /// 獲取屬性值  
        /// </summary>  
        /// <param name="propertyName"></param>  
        /// <returns></returns>  
        public object GetPropertyValue(string propertyName)  
        {  
            if (_values.ContainsKey(propertyName) == true)  
            {  
                return _values[propertyName];  
            }  
            return null;  
        }  
        /// <summary>  
        /// 設置屬性值  
        /// </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>  
        /// 實現動態對象屬性成員訪問的方法，得到返回指定屬性的值  
        /// </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>  
        /// 實現動態對象屬性值設置的方法。  
        /// </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>  
        /// 動態對象動態方法調用時執行的實際代碼  
        /// </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);  
        }  
    }  

 

測試代碼：

           dynamic theObj = new DynObj();  
           theObj.aaa = "this is a test";//動態屬性  
           //動態方法，這里不能沒法定義參數，調用的時候可以是任意多參數，具體參數類型和含義就只能自己去小心處理了.  
           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");