Subject

Rocket.Subject — Type

Subject(::Type{D}; scheduler::H = AsapScheduler())

A Subject is a special type of Observable that allows values to be multicasted to many Observers. Subjects are like EventEmitters. Every Subject is an Observable and an Actor. You can subscribe to a Subject, and you can call next! to feed values as well as error! and complete!.

Note: By convention, every actor subscribed to a Subject observable is not allowed to throw exceptions during next!, error! and complete! calls. Doing so would lead to undefined behaviour. Use safe() operator to bypass this rule.

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Rocket.SubjectFactory — Type

SubjectFactory(scheduler::H) where { H <: AbstractScheduler }

A base subject factory that creates an instance of Subject with specified scheduler.

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Description

Every Subject is an Observable. Given a Subject, you can subscribe to it, providing an Actor, which will start receiving values normally. From the perspective of the Observer, it cannot tell whether the Observable execution is coming from a plain unicast Observable or a Subject.

Internally to the Subject, subscribe does not invoke a new execution that delivers values. It simply registers the given Observer in a list of Observers.

Every Subject is an Actor. It is an object with the methods next!, error!, and complete!. To feed a new value to the Subject, just call next!(subject, theValue), and it will be multicasted to the Actors registered to listen to the Subject.

Note

By convention, every actor subscribed to a Subject observable is not allowed to throw exceptions during next!, error! and complete! calls. Doing so would lead to undefined behaviour. Use safe() operator to bypass this rule.

Examples

In the following example, the BehaviorSubject is initialized with the value 0 which the first Observer receives when it subscribes. The second Observer receives the value 2 even though it subscribed after the value 2 was sent.

using Rocket

subject = Subject(Int)

subscription1 = subscribe!(subject, logger("1"))

next!(subject, 1)
next!(subject, 2)

subscription2 = subscribe!(subject, logger("2"))

next!(subject, 3)

unsubscribe!(subscription1)
unsubscribe!(subscription2)

// Logs
// [1] Data: 1
// [1] Data: 2
// [1] Data: 3
// [2] Data: 3