threeyear
9/7/2013 - 3:03 PM

属性变更

属性变更

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Dynamic;
using System.Reflection;

namespace ConsoleApplication1
{
    class EntityNotifier<T> : DynamicObject where T : new()
    {
        public class ObjectChangedEventArgs : EventArgs
        {
            public string PropertyName { get; set; }
            public object OldValue { get; private set; }
            public ObjectChangedEventArgs(string name, object value)
            {
                PropertyName = name;
                OldValue = value;
            }
        }

        private T innerObject { get; set; }

        public EntityNotifier()
        {
            innerObject = new T();
        }

        public EntityNotifier(T obj)
        {
            innerObject = obj;
        }

        public static implicit operator EntityNotifier<T>(T obj)
        {
            return new EntityNotifier<T>(obj);
        }

        public static implicit operator T(EntityNotifier<T> obj)
        {
            return obj.innerObject;
        }

        public override bool TryGetMember(GetMemberBinder binder, out object result)
        {
            var p = typeof(T).GetProperties().SingleOrDefault(x => x.Name == binder.Name);
            if (p == default(PropertyInfo))
            {
                result = null;
                return false;
            }
            else
            {
                result = p.GetValue(innerObject, new object[] { });
                return true;
            }
        }

        public override bool TrySetMember(SetMemberBinder binder, object value)
        {
            var p = typeof(T).GetProperties().SingleOrDefault(x => x.Name == binder.Name);
            if (p == default(PropertyInfo))
            {
                return false;
            }
            else
            {
                object oldvalue = p.GetValue(innerObject, new object[] { });
                p.SetValue(innerObject, value, new object[] { });
                if (ObjectChanged != null) ObjectChanged(this, new ObjectChangedEventArgs(binder.Name, oldvalue));
                return true;
            }
        }

        public event EventHandler<EntityNotifier<T>.ObjectChangedEventArgs> ObjectChanged;
    }

    class Person
    {
        public int ID { get; set; }
        public string Name { get; set; }
    }

    class Program
    {
        static void Main(string[] args)
        {
            dynamic person = new EntityNotifier<Person>();
            person.ObjectChanged += new EventHandler<EntityNotifier<Person>.ObjectChangedEventArgs>((x, y) => 
            {
                Console.WriteLine("obj.{0} changed.", y.PropertyName);
            });
            person.Name = "张三";
            person.Name = "李四";
            person.ID = 1;
            Person p = person;
            Console.WriteLine(p.Name);
        }
    }
}