.net 每当属性值发生变化时引发事件

INotifyPropertyChanged接口is通过事件实现.该接口只有一个成员PropertyChanged，这是一个消费者可以订阅的事件.

Richard发布的版本不安全.以下是如何安全地实现此接口:

public class MyClass : INotifyPropertyChanged
{
    private string imageFullPath;

    protected void OnPropertyChanged(PropertyChangedEventArgs e)
    {
        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null)
            handler(this, e);
    }

    protected void OnPropertyChanged(string propertyName)
    {
        OnPropertyChanged(new PropertyChangedEventArgs(propertyName));
    }

    public string ImageFullPath
    {
        get { return imageFullPath; }
        set
        {
            if (value != imageFullPath)
            {
                imageFullPath = value;
                OnPropertyChanged("ImageFullPath");
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
}

请注意，这将执行以下操作:

• 抽象属性更改通知方法，以便您可以轻松地将其应用于其他属性；

• 复制试图调用它的PropertyChanged个委托before(如果不这样做，将产生竞争条件).

• 正确实现INotifyPropertyChanged接口.

如果要additionally为正在更改的specific属性创建通知，可以添加以下代码:

protected void OnImageFullPathChanged(EventArgs e)
{
    EventHandler handler = ImageFullPathChanged;
    if (handler != null)
        handler(this, e);
}

public event EventHandler ImageFullPathChanged;

然后在第OnPropertyChanged("ImageFullPath")行之后添加第OnImageFullPathChanged(EventArgs.Empty)行.

既然我们有.Net 4.5存在CallerMemberAttribute，它允许在源代码中go 掉属性名称的硬编码字符串:

    protected void OnPropertyChanged(
        [System.Runtime.CompilerServices.CallerMemberName] string propertyName = "")
    {
        OnPropertyChanged(new PropertyChangedEventArgs(propertyName));
    }

    public string ImageFullPath
    {
        get { return imageFullPath; }
        set
        {
            if (value != imageFullPath)
            {
                imageFullPath = value;
                OnPropertyChanged();
            }
        }
    }