使用Subject.create创建的主题无法退订 [英] Subjects created with Subject.create can't unsubscribe
问题描述
我有一个主题负责订阅某些可观察的内容:
I have a subject that is responsible for subscriptions to certain observable:
var timer$ = Rx.Observable.timer(1000, 2000);
将主题链接到这样的主题
When the subject is linked to the subject like that
var timerSubject = new Rx.Subject;
timer$.subscribe(timerSubject);
var subscription1 = timerSubject.subscribe(n => console.log(n));
var subscription2 = timerSubject.subscribe(n => console.log(n));
setTimeout(() => timerSubject.unsubscribe(), 4000);
一切都很好，timerSubject.unsubscribe()可以被调用一次，并且订阅不应该被一个一个地取消订阅.
everything is fine, timerSubject.unsubscribe() can be called once and the subscriptions shouldn't be unsubscribed one by one.
使用这样的Subject.create创建主题时( plunk )
When the subject is created with Subject.create like that (a plunk)
var timerSubject = Rx.Subject.create(null, timer$);
var subscription1 = timerSubject.subscribe(n => console.log(n));
var subscription2 = timerSubject.subscribe(n => console.log(n));
setTimeout(() => timerSubject.unsubscribe(), 4000);
timerSubject.unsubscribe()不执行任何操作，而我希望它的行为与第一个代码片段相同.
timerSubject.unsubscribe() does nothing, while I would expect to behave it the same as in the first snippet.
如果Subject.create创建了一个甚至无法退订的主题，那么Subject.create的目的是什么?
If Subject.create creates a subject that can't even unsubscribe, what's the purpose of Subject.create then?
为什么会这样?这是一个错误吗?
Why does this happen? Is this a bug?
应该如何创建主题以达到所需的行为?
How can the subject should be created to reach the desired behaviour?
它可以用RxJS 5 RC1复制.
It is reproducible with RxJS 5 RC1.
推荐答案
I checked the source code for Subject.create() and it's not the same as calling new Subject().
-
Subject.create()返回AnonymousSubject的实例.
new Subject()返回Subject的实例.
所以看来AnonymousSubject上的unsubscribe()不起作用的问题是因为它实际上从未订阅.它仅保留对source Observable的引用，并且在订阅观察者时，它直接将source与观察者连接，并且不跟踪创建的订阅.
So it seems the problem why unsubscribe() on AnonymousSubject doesn't work is because it in fact never subscribes. It just keeps a reference to the source Observable and when subscribing an Observer it connects directly source with the Observer and doesn't keep track of created subscribtions.
在您的情况下，当您呼叫timerSubject.subscribe()时，它直接订阅timer$，而AnonymousSubject仅充当中介.
In your case when you call timerSubject.subscribe() it subscribes directly to timer$ and AnonymousSubject acts only as mediator.
我不知道这是设计使然还是错误.但是，我认为第一种选择更有可能.
I don't know whether this is by design or it's a bug. However, the first option is more likely I think.
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