go-bus

go-bus is a plain event bus for Go, allowing otherwise decoupled components to publish and listen for events.

Usage

A simple publish onto the default bus:

bus.SubscribeFunc("greetings", func(b *Bus, topic, value interface{}) {
	log.Printf("Received greeting: %v", value)
})
bus.Publish("greetings", "Good morning Mr Freeman")

Using a custom bus and deregistering a subscriber after use:

b := bus.NewBus()

// Log all kills and deaths to console
eventLogger := func(b *Bus, t, v interface{}) {
	switch ev := v.(type) {
		case Kill:
			log.Printf("You killed %s", ev.Victim)
		case Join:
			log.Printf("%s joined", ev.Player)
	}
}
b.SubscribeFunc("kills", eventLogger)
b.SubscribeFunc("joins", eventLogger)

// Set player flag when Breen is killed
dereg := b.SubscribeFunc("kills", func(b *Bus, t, v interface{}) {
	kill := v.(Kill)
	if kill.Victim == "Breen" {
		flags.KilledBreen = true
		dereg() // stop listening for events
	}
})

// Publish events
b.Publish("kills", Kill{Victim: "Vortigaunt"})
b.Publish("kills", Kill{Victim: "Breen"})

Sending events asynchronously using a non-blocking Publish call via the Async flag:

// Listen for releases, and start download immediately
bus.SubscribeFunc("release", func(b *Bus, t, v interface{}) {
	if err := download(v); err != nil {
		log.Printf("download failed: %v", err)
	}
	log.Printf("%v download complete!", v)
})

// Book holiday for certain releases.
bus.SubscribeFunc("games", func(b *Bus, t, v interface{}) {
	if v == "hl3" {
		bookHoliday(5 * 24 * time.Hour)
	}
})

for releases := range releaseChan {
	// Call asynchronously as handlers may take some time...
	bus.Publish("games", release, Async)
}