C#動态對象(dynamic)示例(實作方法和屬性的動态)

C#的動态對象的屬性實作比較簡單,如果要實作動态語言那種動态方法就比較困難,因為對于dynamic對象,擴充方法,匿名方法都是不能用直接的,這裡還是利用對象和委托來模拟這種動态方法的實作,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:這裡的委托多有個dynamic參數,代表調用這個委托的動态對象本身.

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,這裡用對象去承載:

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) 定義一個動态對象:

public class DynObj : DynamicObject
    {
        //儲存對象動态定義的屬性值
        private Dictionary<string, object> _values;
        public DynObj()
        {
            _values = new Dictionary<string, object>();
        }
        /// <summary>
        /// 擷取屬性值
        /// </summary>
        /// <param name="propertyName"></param>
        /// <returns></returns>
        public object GetPropertyValue(string propertyName)
        {
            if (_values.ContainsKey(propertyName) == true)
            {
                return _values[propertyName];
            }
            return null;
        }
        /// <summary>
        /// 設定屬性值
        /// </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>
        /// 實作動态對象屬性成員通路的方法，得到傳回指定屬性的值
        /// </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>
        /// 實作動态對象屬性值設定的方法。
        /// </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>
        /// 動态對象動态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);
        }
    }      

dynamic theObj = new DynObj();
            theObj.aaa = "this is a test";//動态屬性
            //動态方法，這裡不能沒法定義參數，調用的時候可以是任意多參數，具體參數類型和含義就隻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");