当实现 INotifyPropertyChanged 时，C# 中的 [NotifyPropertyChangedInvocator] 是什么? [英] What is [NotifyPropertyChangedInvocator] in C# when implements INotifyPropertyChanged?

问题描述

我看到了两种类型的 INotifyPropertyChanged

• 第一个:

• The first one:

public abstract class ViewModelBase : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

第二个:

The second one:

public abstract class ViewModelBase : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    [NotifyPropertyChangedInvocator]
    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

在第二个中，您看到方法 OnPropertyChanged

In 2nd one you see there is an extra attribute [NotifyPropertyChangedInvocator] on the method OnPropertyChanged

在我的情况下，两者的行为相同，但是什么，为什么以及何时使用此 [NotifyPropertyChangedInvocator]，这样做有什么好处?我在互联网上搜索过，但找不到任何好的答案.

In my case both behaves same but what, why and when to use this [NotifyPropertyChangedInvocator], what are benefits of this? I've searched on internet but couldn't find any good answer.

推荐答案

这是一个 Resharper 属性，来自他们的 注释 - 旨在向您发出警告，然后您的代码看起来很可疑 :)
考虑一下:

It is a Resharper attribute from their Annotations - designed to give you warning then your code looks suspicious :)
Consider this:

public class Foo : INotifyPropertyChanged 
{
     public event PropertyChangedEventHandler PropertyChanged;

     [NotifyPropertyChangedInvocator]
     protected virtual void NotifyChanged(string propertyName) { ... }

     private string _name;
     public string Name {
       get { return _name; }
       set { 
             _name = value; 
             NotifyChanged("LastName");//<-- warning here
           } 
     }
   }

使用 [NotifyPropertyChangedInvocator] 属性在 NotifyChanged 方法上Resharper 会给你一个警告，你正在调用带有 (大概)错误的值.

因为 Resharper 现在知道应该调用 方法来发出更改通知，它将帮助您将普通属性转换为带有更改通知的属性:
转换成这个:

With the [NotifyPropertyChangedInvocator] attribut on the NotifyChanged method Resharper will give you a warning, that you are invoking the method with a (presumably) wrong value.

Because Resharper now knows that method should be called to make change notification, it will help you convert normal properties into properties with change notification:
Converting it into this:

public string Name
{
  get { return _name; }
  set
  {
    if (value == _name) return;
    _name = value;
    NotifyChange("Name");
  }
}

此示例来自关于 [NotifyPropertyChangedInvocator] 属性的文档:

This example is from the documentation on the [NotifyPropertyChangedInvocator] attribute found here:

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