Question

我正在尝试生成进度消息并通过IObservable发布。

Func<JobProgressMessage> nextMsg = () => ProgressManager.InProgressMessage("progressing");

var o = Observable
    .Return(nextMsg())
    .Repeat()
    .Timeout(TimeSpan.FromSeconds(2))
    .Retry(100)
    .Finally(() =>
        job.AddMessage<ProgressCompleted>(ProgressManager.CompletedMessage("Completed")));

我发现nextMsg()仅在同一条消息发布后进行评估。我希望Repeat每次都会导致lambda重新评估。

Answer 1

每当您订阅observable时需要重新评估某些内容（包括Defer重复订阅），Func<JobProgressMessage> nextMsg = () => ProgressManager.InProgressMessage("progressing"); var o = Observable .Defer(() => Observable .Return(nextMsg())) .Repeat() .Timeout(TimeSpan.FromSeconds(2)) .Retry(100) .Finally(() => job.AddMessage<ProgressCompleted>ProgressManager.CompletedMessage("Completed")));就是您想要的：

Defer

基本上，在订阅时，nextMsg会评估传入的函数，以便在每个订阅上获得新的observable。然后，当然UPDATE TAB_EXAM_FORMS SET RNO_CODE = CAST(RAND(CHECKSUM(NEWID())) * 10 AS INT) + 1也将被重新评估。

Answer 2

根据nhabuiduc的建议，最简单的方法是

var o = Observable.Return(ProgressManager.InProgressMessage("progressing"))
                          .Repeat()
                          .Timeout(TimeSpan.FromSeconds(2))
                          .Retry(100)
                          .Finally(() => job.AddMessage<ProgressCompleted>(ProgressManager.CompletedMessage("Completed")));

var s = o.Subscribe(m => job.AddMessage(ProgressManager.InProgressMessage("progressing")));

但最后，我想玩Observables，我最终得到了

var s = Observable.Defer(()=>Observable.Return(nextMsg()))
                  .Delay(TimeSpan.FromSeconds(2))
                  .Repeat(100)
                  .Finally(() => job.AddMessage<ProgressCompleted>(ProgressManager.CompletedMessage("Completed")))
                  .SubscribeOn(Scheduler.ThreadPool)
                  .Subscribe(m => job.AddMessage(m));

强制lambda重新评估作为Rx序列的一部分

2 个答案: