反应式扩展 - 可观察.FromEvent 类型转换

Question

我正在尝试使用反应式扩展动手实验室，但无法使用 FromEvent API 注册（我收到编译时异常）。我想在文本框控件上调用 textchanged 属性时接收事件，有人可以建议我在通过 FromEvent API 进行转换时做错了什么吗？我有些无法键入转换或从TextChangeEventArgs/EventHandler转换为EventHandler - 请告诉我正确的方法。谢谢。

        internal delegate void TextChangedEventArgs(object sender, EventArgs e);
        var txt = new TextBox();
        var form = new Form
                      {
                          Controls = { txt }
                      };

        var subscription = Observable.FromEvent<EventHandler, TextChangedEventArgs>(
           x => (a, b) => new EventHandler(), ??????
           x => txt.TextChanged += x, 
           x => txt.TextChanged -= x
           );
       IDisposable eventSubscription = subscription.Subscribe(
           x => Console.WriteLine("Subscriber Got " + x),
           x => Console.WriteLine("An exception has occured" + x),
           () => Console.WriteLine("Action completed"));
        Console.WriteLine("in here");
       using (new CompositeDisposable(eventSubscription)) { Application.Run(form); }
        Console.ReadKey();

Answer 1

试试这个：

var subscription = Observable.FromEventPattern<TextChangedEventArgs>(txt, "TextChanged"); 

Answer 2

尝试：

var subscription = Observable.FromEvent(h => txt.TextChanged += h,
                                        h => txt.TextChanged -= h);

Answer 3

试试这个（编辑：如果你的目标是Windows Phone Reactive API）：

var subscription = Observable.FromEvent<TextChangedEventArgs>(txt, "TextChanged");