在WPF中实现INotifyPropertyChanged接口的辅助snippets

http://www.cnblogs.com/alexou/archive/2009/10/17/1585288.html

在Silverlight与WPF的开发过程中，为了使用Binding技术，往往要将自己的实体类实现INotifyPropertyChanged接口。但为每一个Property书写调用接口，并不是省时省力的事情，而且在硬编码属性的NAME，也可能会在以后的重构过程中引入潜在的Bug。在参考了下面两篇文章后，使用Lambda表达式与snippet快速的完成实体类的属性声明。

 

http://www.jphamilton.net/blog/post/MVVM-with-Type-Safe-INotifyPropertyChanged.aspx

http://www.designerwpf.com/2009/04/30/inotifypropertychanged-snippets-and-why-you-should-use-these-instead-of-dependencyproperties/

重要的是two-way绑定数据时，使用IPropertyChanged（针对standalone data），而不是DependencyProperty(这个针对Control)

**********************

It turns out I had gotten confused. I understood that DependencyProperties were good for the following:

• Providing callbacks when the property is changed
• Binding to stuff
• Animations

I figured that this is the kind of behavior I wanted from my data. I was wrong. As it turns out that is the kind of behavior I want out of the properties that I use in my WPF and Silverlight controls. It seems that DependencyProperties are meant to be used with controls and not for stand-alone data.

For stand-alone data, I should have used INotifyPropertyChanged, which is an interface for… well… notifying things when a property changes.

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 1     public abstract class ViewModel<MODEL> : INotifyPropertyChanged
 2     {
 3         public event PropertyChangedEventHandler PropertyChanged;
 4         protected void RaisePropertyChanged<R>(Expression<Func<MODEL, R>> x)
 5         {
 6             var body = x.Body as MemberExpression;
 7             if (body == null)
 8                 throw new ArgumentException("请输入属性的引用");
 9             string propertyName = body.Member.Name;
10             PropertyChangedEventHandler handler = this.PropertyChanged;
11             if (handler != null)
12             {
13                 var e = new PropertyChangedEventArgs(propertyName);
14                 handler(this, e);
15             }
16         }
17     }

 

 首先定义基类，所有的实体类，均需从ViewModel<>类派生出来。

 之后，创建一个snippet。将下面的代码，另存为INotifyProperty.snippet，并保存到Visual Studio的相应目录中，例如我的VS2008中，目录为：C:/Program Files/Microsoft Visual Studio 9.0/VC#/Snippets/2052/Visual C#

<?xml version="1.0" encoding="utf-8" ?>
<CodeSnippets xmlns="http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet">
  <CodeSnippet Format="1.0.0">
    <Header>
      <Title>INotifyPropertyChanged Property: Use this to create a new property INotifyPropertyChanged implementation.</Title>
      <Shortcut>notifyp</Shortcut>
      <Description>This class must inherited from ViewModel or implements RaisePropertyChanged method.</Description>
      <Author>alexou</Author>
      <SnippetTypes>
        <SnippetType>Expansion</SnippetType>
      </SnippetTypes>
    </Header>
    <Snippet>
            <Declarations>
                <Literal>
                    <ID>PropertyName</ID>
                    <ToolTip>The name of the private property</ToolTip>
                    <Default>MyProperty</Default>
                </Literal>
                <Literal>
                    <ID>type</ID>
                    <ToolTip>The type of the property (e.g. string, double, bool, Brush, etc.)</ToolTip>
                    <Default>string</Default>
                </Literal>
            </Declarations>
      <Code Language="csharp">
        <!--[CDATA[
        private $type$ _$PropertyName$;
               
        public $type$ $PropertyName$
        {
            get{ return _$PropertyName$;}
            set
            {
                _$PropertyName$ = value;
                RaisePropertyChanged(item => item.$PropertyName$);
            }
        }
        $end$]]-->
      </Code>
    </Snippet>
  </CodeSnippet>
</CodeSnippets>
 现在开始声明自己的实体类，举个简单的例子：声明一个Person类，里面应当由诸如Name，Age，Sex，Phone等通用属性，只需要按照下面的方式，就可以非常快速并且安全的声明相应的成员变量和INotifyPropertyChanged接口的调用方法。

public class Person : ViewModel<Person>
{
  notifyp
  //->这里按TAB键，输入属性名和属性类型，如Name， String
}
//就会自动生成
public class Person : ViewModel<Person>
{
        private string _Name;
        public string Name
        {
            get { return _Name; }
            set
            {
                _Name = value;
                RaisePropertyChanged(item => item.Name);
            }
        }
}