菲佣WPF——3(关于NotifyObject重大bug修复)

之前的NotifyObjec有问题。是多个属性同时对一个Object进行操作。

新代码如下。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.ComponentModel;
using System.Linq.Expressions;

namespace WpfApplication4
{
    public abstract class NotifyObject:INotifyPropertyChanged
    {
        #region << Field >>
        private Dictionary<string, object> cache = new Dictionary<string, object>();
        #endregion

        #region << Property >>
        public event PropertyChangedEventHandler PropertyChanged;
        #endregion

        #region << Method >>
        public T GET<T>(Expression<Func<T>> express)
        {
            return GetPropertyValue<T>(GetPropertyName<T>(express));
        }

        public void SET<T>(Expression<Func<T>> express, object obj)
        {
            SetPropertyValue(GetPropertyName<T>(express), obj);
        }

        private string GetPropertyName<T>(Expression<Func<T>> express)
        {
            var memExpress = (MemberExpression)express.Body;

            if (memExpress == null)
                throw new Exception("The expression is valid");

            return memExpress.Member.Name;
        }

        private T GetPropertyValue<T>(string propertyName)
        {
            if (string.IsNullOrEmpty(propertyName))
                return default(T);
            else
            {
                if (cache.ContainsKey(propertyName))
                    return (T)cache[propertyName];
                else
                    return default(T);
            }
        }

        private void SetPropertyValue(string propertyName, object obj)
        {
            if (cache.ContainsKey(propertyName))
            {
                if (!Object.ReferenceEquals(cache[propertyName], obj))
                {
                    cache[propertyName] = obj;
                    Notify(propertyName);
                }
            }
            else
            {
                cache.Add(propertyName, obj);
                Notify(propertyName);
            }
        }

        private void Notify(string propertyName)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
        #endregion
    }
}