Expression 反射調用TryParse

public static class StringExtenssion
    {
        #region ///string 轉其他類型資料
        /// <summary>
        /// TryParse委托
        /// </summary>
        /// <typeparam name="TStr">String</typeparam>
        /// <typeparam name="TOut">Out T</typeparam>
        /// <typeparam name="TResult">傳回值</typeparam>
        /// <param name="str">要轉換的字元串</param>
        /// <param name="outValue">out 輸出參數</param>
        /// <returns>成功true,失敗false</returns>
        public delegate TResult FuncEx<T1, TOut, TResult>(T1 str, out TOut outValue);


        /// <summary>
        /// Parse
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="str"></param>
        /// <param name="defaultValue"></param>
        /// <returns></returns>
        public static T Parse<T>(this string str)
        {
            Type t = typeof(T);
            var param_str = Expression.Parameter(typeof(string));
            var method = typeof(T).GetMethod("Parse", new Type[] { typeof(string)});
            //方法不存在
            if (method == null)
            {
                throw new Exception("找到不Parse方法");
            }
            var methodExp = Expression.Call(method, param_str);
            var parse = Expression.Lambda<Func<string,T>>(methodExp, param_str).Compile();
            return parse(str);
        }

        /// <summary>
        /// TryParse
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="str"></param>
        /// <param name="defaultValue"></param>
        /// <returns></returns>
        public static T TryParse<T>(this string str, T defaultValue)
        {
            Type t = typeof(T);
            T outValue = defaultValue;
            var param_str = Expression.Parameter(typeof(string));
            var param_outValue = Expression.Parameter(typeof(T).MakeByRefType());
            var method = typeof(T).GetMethod("TryParse", new Type[] { typeof(string), typeof(T).MakeByRefType() });
            //方法不存在
            if (method == null)
            {
                return defaultValue;
            }
            var methodExp = Expression.Call(method, param_str, param_outValue);
            var tryParse = Expression.Lambda<FuncEx<string, T, bool>>(methodExp, param_str, param_outValue).Compile();
            return tryParse(str, out outValue) ? outValue : defaultValue;
        }
        #endregion
    }