blocks|key|5028354|text|实现由lambda显式创建的闭包：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5028355|private+void+ListenToPropertyChangedEvent(INotifyPropertyChanged+source,
++++++++++++++++++++++++++++++++++++++++++string+propertyName)
{
++++var+listener+=+new+MyPropertyChangedListener(propertyName);
++++source.PropertyChanged+%2B=+listener.Handle;
}

class+MyPropertyChangedListener
{
++++private+readonly+string+propertyName;

++++public+MyPropertyChangedListener(string+propertyName)
++++{
++++++++this.propertyName+=+propertyName;
++++}

++++public+void+Handle(object+sender,+PropertyChangedEventArgs+e)
++++{
++++++++if+(e.PropertyName+==+this.propertyName)
++++++++{
++++++++++++//+do+something
++++++++}
++++}
}|code-block|syntax|javascript|5028356|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Implement the closure that is implicitly created by the lambda explicitly:

<pre><code>private void ListenToPropertyChangedEvent(INotifyPropertyChanged source,
 string propertyName)
{
 var listener = new MyPropertyChangedListener(propertyName);
 source.PropertyChanged += listener.Handle;
}

class MyPropertyChangedListener
{
 private readonly string propertyName;

 public MyPropertyChangedListener(string propertyName)
 {
 this.propertyName = propertyName;
 }

 public void Handle(object sender, PropertyChangedEventArgs e)
 {
 if (e.PropertyName == this.propertyName)
 {
 // do something
 }
 }
}
</code></pre>

blocks|key|2957541|text|您可以通过对所有使用您所遵循的实例字典的实例使用单个事件处理程序来处理此问题：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2957542|private+Dictionary<INotifyPropertyChanged,+List<string>>+sourceMap+=
++++new+Dictionary<INotifyPropertyChanged,+List<string>>();

private+void+ListenToPropertyChangedEvent(INotifyPropertyChanged+source,
++++++++++++++++++++++++++++++++++++++++++++string+propertyName)
{
++++if+(sourceMap.ContainsKey(source))
++++++++sourceMap[source].Add(propertyName);
++++else
++++{
++++++++source.PropertyChanged+%2B=+source_PropertyChanged;
++++++++sourceMap[source]+=+new+List<string>+{+propertyName+};
++++}
}

void+source_PropertyChanged(object+sender,+PropertyChangedEventArgs+e)
{
++++var+source+=+sender+as+INotifyPropertyChanged;
++++var+list+=+sourceMap[source];
++++if+(list.Contains(e.PropertyName))
++++++++MyMagicMethod();
}|code-block|syntax|javascript|2957543|这个版本没有任何错误检查或删除，但它演示了这项技术。如果您通过侦听来自同一个源的多个属性，这一点尤为重要。这是因为它只向每个实例的PropertyChanged事件添加一个处理程序。|offset|length|style|BOLD|CODE|2957544|entityMap^0|0|0|V|8|1T|F|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Q|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|R|8|@$I|S|J|T|K|L]|$I|U|J|V|K|M]]|9|@]|A|$]]|$1|N|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|O|$]]

You can handle this by having a single event handler for all instances that uses a dictionary of instances that you are following:

<pre><code>private Dictionary&lt;INotifyPropertyChanged, List&lt;string&gt;&gt; sourceMap =
 new Dictionary&lt;INotifyPropertyChanged, List&lt;string&gt;&gt;();

private void ListenToPropertyChangedEvent(INotifyPropertyChanged source,
 string propertyName)
{
 if (sourceMap.ContainsKey(source))
 sourceMap[source].Add(propertyName);
 else
 {
 source.PropertyChanged += source_PropertyChanged;
 sourceMap[source] = new List&lt;string&gt; { propertyName };
 }
}

void source_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
 var source = sender as INotifyPropertyChanged;
 var list = sourceMap[source];
 if (list.Contains(e.PropertyName))
 MyMagicMethod();
}
</code></pre>

This version doesn't have any error checking or removal but it demonstrates the technique. It is particularly valuable if you listen for multiple properties from the same source. This is because it only adds a single handler to the <code>PropertyChanged</code> event per instance.

blocks|key|5028479|text|我不确定你到底想要达到什么目的，或者为什么你不想使用匿名方法，但你可以做一些更通用的事情：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|5028480|++++private+PropertyChangedEventHandler+GetHandler
++++++(Func<PropertyChangedEventArgs,+bool>+test,+Action+toInvoke)
++++{
++++++++return+new+PropertyChangedEventHandler(
++++++++++++(o,+e)+=>+
++++++++++++{
+++++++++++++++if+(test(e))
++++++++++++++++toInvoke();+
++++++++++++});+
++++}|code-block|syntax|javascript|5028481|然后你可以像这样使用它：|5028482|++source.PropertyChanged+%2B=+GetHandler++++++++++++++++
++++++++++++(
++++++++++++++++p+=>+p.PropertyName+==+propertyName,+MyMagicMethod
++++++++++++);+|5028483|这样，您的if测试和目标方法组就可以很容易地进行交换。您的事件处理程序也是强类型的，而不是匿名的。|5028484|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

I'm not sure exactly what youre trying to achieve or why you dont want to use anonymous methods, but you could do something more generic:

<pre><code> private PropertyChangedEventHandler GetHandler
 (Func&lt;PropertyChangedEventArgs, bool&gt; test, Action toInvoke)
 {
 return new PropertyChangedEventHandler(
 (o, e) =&gt; 
 {
 if (test(e))
 toInvoke(); 
 }); 
 }
</code></pre>

Then you can use it like so:

<pre><code> source.PropertyChanged += GetHandler 
 (
 p =&gt; p.PropertyName == propertyName, MyMagicMethod
 ); 
</code></pre>

That way your if test and the target method group can be swapped about easily. Your event handler is also strongly typed rather than anonymous.

How could I refactor the method

<pre><code>private void ListenToPropertyChangedEvent(INotifyPropertyChanged source,
 string propertyName)
{
 source.PropertyChanged += (o, e) =&gt;
 {
 if (e.PropertyName == propertyName)
 MyMagicMethod();
 };
}
</code></pre>

if I wished to avoid using the anonymous method here?

How to avoid anonymous methods in "dynamic" event subscription?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

教程

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云智能顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

聚焦“写作效率、视觉美观与运行性能”三方面进行全面升级，为您提供更高效、稳定的创作环境

社区富文本&Markdown编辑器全新改版上线，欢迎大家体验!

诚挚邀请您参与本次调研，分享您的真实使用感受与建议。您的反馈至关重要，感谢您的支持与参与！

社区新版编辑器体验调研

我如何重构这个方法private void ListenToPropertyChangedEvent(INotifyPropertyChanged source,                                          string propertyName){    source.Prope...

问如何避免“动态”事件订阅中的匿名方法？
EN

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问如何避免“动态”事件订阅中的匿名方法？EN