Pub/Sub example from Kyle Lemons. For further study as it contains a few new channel actions that I don't yet get.

pubsub.go

package main

import "fmt"

const Buffer = 3

type Value int

type Producer struct {
  subs	map[chan Value]bool
	sub	chan chan Value
	unsub	chan chan Value
}

func NewProducer() *Producer {
	p := &Producer{
		subs:	make(map[chan Value]bool),
		sub:	make(chan chan Value),
		unsub:	make(chan chan Value),
	}
	values := make(chan Value)
	go func() {
		for i := Value(0); ; i++ {
			values <- i
		}
	}()
	go func() {
		next := make(chan Value, Buffer)
		for {
			select {
			case v := <-values:
				for c := range p.subs {
					select {
					case c <- v:
					default:
					}
				}
			case p.sub <- next:
				p.subs[next], next = true, make(chan Value, Buffer)
			case c := <-p.unsub:
				delete(p.subs, c)
			}
		}
	}()
	return p
}

func (p *Producer) Subscribe() chan Value {
	return <-p.sub
}

func (p *Producer) Unsubscribe(ch chan Value) {
	p.unsub <- ch
}

func main() {
	p := NewProducer()
	ch := p.Subscribe()
	defer p.Unsubscribe(ch)
	for i := 0; i < 10; i++ {
		fmt.Println(i, <-ch)
	}
}

Line 22-26 are just a dummy fill function for the channel, it blocks when it gets to 3 (Buffer) anyway.

Line 39 confused me, but the #go-nuts guys (Kyle included!) pointed out that it's p.subs[next] = true; next=make(..)

All good. I've learnt a lot from these 63 lines of code.