INotifyPropertyChanged和propertyName [英] INotifyPropertyChanged and propertyName

问题描述

在实现INotifyPropertyChanged时，我从不知道propertyName的含义.因此，通常将INotifyPropertyChanged实现为:

public class Data : INotifyPropertyChanged {
   public event PropertyChangedEventHandler PropertyChanged;

   private void NotifyPropertyChanged(string propertyName = "") {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));

   private string itsID;
   public string ID { 
             get { return itsID; }
             set { 
                   if (itsID != value) {
                     itsID = value; 
                     NotifyPropertyChanged("ID");
                  }
   }
}

我从不知道NotifyPropertyChanged(string propertyName)的propertyName参数.

1. 那可以是任意字符串(如上例中的"MyID")吗?
2. 或者.NET是否使用Reflection将其与类中的属性对齐，因此它必须与属性名称完全匹配?
3. 如果propertyName与Property的名称不完全一样，.NET是否会将整个对象视为changed?

解决方案

它本身不是.NET Framework本身，几乎是每个PropertyChanged订阅者的一部分(其中的某些确实确实是作为框架)，假设您通过发送属性名称按预期使用了接口.如果您发送属性MyID更改的通知，则当另一个组件正在查看属性ID时，它通常会看到该通知，比较名称，并得出此通知不适合我"的结论. /p>

I was never sure about the meaning of propertyName when implementing INotifyPropertyChanged. So generally you implement INotifyPropertyChanged as:

public class Data : INotifyPropertyChanged {
   public event PropertyChangedEventHandler PropertyChanged;

   private void NotifyPropertyChanged(string propertyName = "") {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));

   private string itsID;
   public string ID { 
             get { return itsID; }
             set { 
                   if (itsID != value) {
                     itsID = value; 
                     NotifyPropertyChanged("ID");
                  }
   }
}

I was never sure about the propertyName argument to NotifyPropertyChanged(string propertyName).

1. Can that be any arbitrary string (like "MyID" in the above example)?
2. Or does .NET use Reflection to align it with a property in a class so it has to match the name of the property exactly?
3. What if the propertyName doesn't match the name of the Property exactly, does .NET consider the entire object as changed?

解决方案

It's not .NET Framework itself per se, it's pretty much every PropertyChanged subscriber out there (some of which do indeed happen to be distributed as part of the framework) that assumes you use the interface as intended, by sending the property name. If you send a notification that the property MyID has changed, when another component is looking at the property ID, it will typically see the notification, compare the names, and conclude "this notification isn't for me".

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