Question

GitHub上的

This问题可以概括为。我正在使用timer()，其重复计划为1秒以执行某些任务。我将其与Subscriber配对以订阅间隔。当某个模型的数据用完时，我将取消订阅并等待新的到来。当他们的数据再次填充时，我尝试再次订阅，但是它不起作用。原来，当Subscriber被取消订阅后，我无法再次使用它。因此，我必须将其替换为Observer。一个新手，我不知道该怎么做。尝试看一些例子，他们只是让我进一步困惑。

如何将以下代码替换为Observer来起作用？

private timer = timer(1000, 1000);

// A timer subscription that keeps sending new images to the observer
timerSubscription = new Subscriber(() => {

    // Check if there is an element in the list
    if (this.head != null) {

      // If the current node at head is a folder, unsubscribe the listener
      if (this.head.data['id'].startsWith('folder')) {
        this.timerSubscription.unsubscribe();
      }

      // Pop a node from the list and pass on to observer
      this.observer.next(this.this$PiFrame.pop());

    } else {

      // If no nodes are left, unsubscribe from the timer
      this.timerSubscription.unsubscribe();

      console.log('No items left on the queue. Deactivating timer subscription.');
    }
  }, e => {}, () => {});

我这样订阅：

    ...
    // Setup a timer to pop every 1000 ms
    this.timer.subscribe(this.this$PiFrame.timerSubscription);
    ...
    // If no nodes are left, unsubscribe from the timer
    this.timerSubscription.unsubscribe();
    ...

Answer 1

让Observable返回订阅，而不是像您那样创建订阅。

将逻辑保持在函数中，如下所示：

  doWhatever() {
    console.log("tick")

    // Check if there is an element in the list
    if (this.head != null) {

      // If the current node at head is a folder, unsubscribe the listener
      if (this.head.data['id'].startsWith('folder')) {
        this.timerSubscription.unsubscribe();
      }

      // Pop a node from the list and pass on to observer
      this.observer.next(this.this$PiFrame.pop());

    } else {

      // If no nodes are left, unsubscribe from the timer
      this.timerSubscription.unsubscribe();

      console.log('No items left on the queue. Deactivating timer subscription.');
    }
  }

然后，当您要订阅时：

this.timerSubscription = this.timer.subscribe(() => this.doWhatever());

这可以重复使用，因为每个subscribe都会产生一个新的Subscription

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