暂停，在恢复时给出最后暂停的值 [英] Pause, upon resume give last paused value

问题描述

我有一个由套接字提供的热 Observable.我可以使用 pausable 暂停套接字馈送.但是，一旦我取消暂停"可观察对象，我就需要显示订阅暂停时套接字可能发送的最后一个值.我不想跟踪套接字手动发送的最后一个值.这怎么可能是可行的?

I have a hot Observable fed by a socket. I can use the pausable to pause the socket feed. But once I 'unpause' the observable, I need to display the last values that the socket could have sent while the subscription was paused. I don't want to keep track of the last values the socket sends manually. How could this be pausible?

从文档中的示例，请参阅下面的注释:

From the example in the documentation, see comments below:

var pauser = new Rx.Subject();
var source = Rx.Observable.fromEvent(document, 'mousemove').pausable(pauser);

var subscription = source.subscribe(
    function (x) {
        //somehow after pauser.onNext(true)...push the last socket value sent while this was paused...
        console.log('Next: ' + x.toString());
    },
    function (err) {
        console.log('Error: ' + err);
    },
    function () {
        console.log('Completed');
    });

// To begin the flow
pauser.onNext(true); 

// To pause the flow at any point
pauser.onNext(false);  

推荐答案

您甚至不需要 pausable 来执行此操作.(还要注意，您标记了 RxJS5，但 pausable 仅存在于 RxJS 4 中).您只需要将 pauser 转换为更高阶的 Observable:

You don't even need pausable to do this. (Note as well that you tagged RxJS5 but pausable only exists in RxJS 4). You simply need to convert your pauser into a higher order Observable:

var source = Rx.Observable.fromEvent(document, 'mousemove')
  // Always preserves the last value sent from the source so that
  // new subscribers can receive it.
  .publishReplay(1);

pauser
  // Close old streams (also called flatMapLatest)
  .switchMap(active => 
    // If the stream is active return the source
    // Otherwise return an empty Observable.
    Rx.Observable.if(() => active, source, Rx.Observable.empty())
  )
  .subscribe(/**/)

//Make the stream go live
source.connect();

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