Is there a 'Hot' equivalent of Observable.Interval

问题

If I do the following:

var obs = 
    Observable
    .Interval(TimeSpan.FromSeconds(1))
    .Select(x => "A" + x.ToString());

obs
.Subscribe(x => Console.WriteLine("From first: " + x.ToString()));

Observable
.Timer(TimeSpan.FromSeconds(3))
.SelectMany(_ => obs)
.Subscribe(x => Console.WriteLine("From second: " + x.ToString()));

I will get this after 4 seconds:

From first:  A0
From first:  A1
From first:  A2
From second: A0
From first:  A3

Is there a 'Hot' equivalent to Observable.Interval that would produce this:

From first:  A0
From first:  A1
From first:  A2
From second: A3
From first:  A3

回答1:

using Publish() and Connect() will turn your cold observable hot.

var published = Observable
   .Interval(...)
   .Select(...)
   .Publish();

var connectionSubscription = published.Connect();
var observerSubscription = published.Subscribe(...);

Worth noting that the sequence is hot once the Connect() call happens. You can subscribe before the Connect() but make sure you call it at some stage or nothing will ever be observed. There are some alternatives to Connect() e.g. RefCount() so worth a google. Also worth noting that Publish() returns an IConnectableObservable which provides the Connect() call.

来源：https://stackoverflow.com/questions/29751884/is-there-a-hot-equivalent-of-observable-interval