How to store functions in a slice in Go

Question

I'm trying to port the following Python functionality to Golang. Especially, how to store functions in a slice and then call them. How can I do this in Golang?

class Dispatcher(object):
    def __init__(self):
        self._listeners = []

    def addlistener(self, listener):
        self._listeners.append(listener)

    def notifyupdate(self):
        for f in self._listeners:
            f()

def beeper():
    print "beep...beep...beep"

def pinger():
    print "ping...ping...ping"

dispatch = Dispatcher()
dispatch.addlistener(beeper)
dispatch.addlistener(pinger)
dispatch.notifyupdate()

output:
beep...beep...beep

ping...ping...ping

Answer 1

It's pretty easy actually:

package main

import "fmt"

func main() {
    var fns []func()
    fns = append(fns, beeper)
    fns = append(fns, pinger)

    for _, fn := range fns {
        fn()
    }
}

func beeper() {
    fmt.Println("beep-beep")
}

func pinger() {
    fmt.Println("ping-ping")
}

Playground: http://play.golang.org/p/xuDsdeRQX3.

Answer 2

Alternatively, if you want an even closer structure (admittedly, not needed, at all, in this case):

package main

import "fmt"

type dispatcher struct {
    listeners []func()
}

func (d *dispatcher) addListener(f func()) {
    d.listeners = append(d.listeners, f)
}

func (d *dispatcher) notify() {
    for _, f := range d.listeners {
        f()
    }
}

func ping() {
    fmt.Println("Ping... ping...")
}

func beep() {
    fmt.Println("Beep... beep...")
}

func main() {
    d := dispatcher{}
    d.addListener(ping)
    d.addListener(beep)
    d.notify()
}

Go playground