c# - 通过匿名委托(delegate)取消订阅事件

Question

我想知道如何取消订阅事件中的匿名方法。

我已经检查过Unsubscribe anonymous method in C#但我的情况略有不同。

我正在匿名方法中访问本地函数变量。

代码如下

 private static void Test(Object dependencyObject, DependencyPropertyChangedEventArgs dependencyPropertyChangedEventArgs)
    {
        if (dependencyPropertyChangedEventArgs.OldValue is ObservableCollection<object>)
        {
            (dependencyPropertyChangedEventArgs.OldValue as ObservableCollection<object>).CollectionChanged -=
                (s, e) => SelectedItemsChanged(dependencyObject, e); // TO FIX event unbsubscription via anonymous delegate
        }

        if (dependencyPropertyChangedEventArgs.NewValue is ObservableCollection<object>)
        {
            (dependencyPropertyChangedEventArgs.NewValue as ObservableCollection<object>).CollectionChanged +=
                (s, e) => SelectedItemsChanged(dependencyObject, e);
        }
    }

Answer 1

您不能使用匿名委托(delegate)来做到这一点。 为了能够取消订阅，您必须使用通常委托(delegate)。