fresnel/fan_out

An actor that distributes published messages to all subscribed subject. Subjects can be dynamically subscribed or unsubscribed from the publisher.

Types

Message

</>

Messages that can be sent to the fan_out publisher actor.

pub type Message(e) {
  Subscribe(Subject(e))
  Unsubscribe(Subject(e))
  Publish(e)
}

Constructors

```
Subscribe(Subject(e))
```
Add a new subscriber that will begin receiving events
```
Unsubscribe(Subject(e))
```
Remove a subscriber from receiving published messages
```
Publish(e)
```
Publish an event to all subscribers

Functions

handler

</>

pub fn handler(
  msg: Message(a),
  subscribers: List(Subject(a)),
) -> Next(Message(a), List(Subject(a)))

The handler to start the round robin actor

Examples:

import fresnel/fan_out
import gleam/otp/actor
import gleam/erlang/process
import gleam/io

type Event {
  Lights
  Camera
  Action
}

fn subscriber(event: Event, id: String) -> actor.Next(Event, String) {
  case event {
    Lights -> {
      io.println(id<>": lights")
      actor.continue(id)
    }
    Camera -> {
      io.println(id<>": camera")
      actor.continue(id)
    }
    Action -> {
      io.println(id<>": action!")
      actor.continue(id)
    }
  }
}

pub fn main() {
  let assert Ok(publisher) = actor.start([], fan_out.handler)  
  let assert Ok(listener1) = actor.start("1", subscriber)
  let assert Ok(listener2) = actor.start("2", subscriber)
  process.send(publisher, Lights)
  process.send(publisher, Camera)
  process.send(publisher, Action)
}