An example of a primitive way to implement an event system in Go using channels and goroutines.

events.go

package main

import (
	"fmt"
)

type SomeEvent struct {
	callbacks []func(int)
	cc        chan int
}

func NewSomeEvent() *SomeEvent {
	se := &SomeEvent{
		[]func(int){},
		make(chan int),
	}

	// start up the goroutine that watches for events
	go func() {
		// reads from the channel until it's closed (blocks while the channel is empty)
		for i := range se.cc {
			// loop over all the callback passing the most recently read value from the channel
			for _, call := range se.callbacks {
				call(i)
			}
		}
	}()
	
	return se
}

func (s *SomeEvent) register(f func(int)) {
	s.callbacks = append(s.callbacks, f)
}

func (s *SomeEvent) fire(i int) {
	s.cc <- i
}

// create the event thingy as global for convenience.
// There are probably better ways to handle this.
var someEvent = NewSomeEvent()

func main() {
	// register a couple handlers
	someEvent.register(func (i int) {
		fmt.Println("Some Event (1): ", i)
	})

	someEvent.register(func (i int) {
		fmt.Println("Some Event (2): ", i)
	})

	// fire the events
	someEvent.fire(12)
	someEvent.fire(1)
	someEvent.fire(-42)
}

// $ go run events.go 
// Some Event (1):  12
// Some Event (2):  12
// Some Event (1):  1
// Some Event (2):  1
// Some Event (1):  -42
// Some Event (2):  -42