A simple PubSub implementation in CoffeeScript

tinysub.coffee

# Simple PubSub implementation
tinysub = do (lib={}) ->

  # Storage for topics that can be broadcast or listened to.
  topics = {}

  # Used to generate subscriber tokens
  subscriber_uid = -1
  generate_token = -> (++subscriber_uid).toString()

  # Publish or broadcast events of interest with a specific topic name and
  # arguments such as the data to pass along.
  lib.publish = (topic, args) ->
    subscribers = topics[topic]
    return false unless subscribers?.length
    sub.func(topic, args) for sub in subscribers
    this

  # Subscribe to events of interest with a specific topic name and a callback
  # function, to be executed when the topic/event is observed.
  lib.subscribe = (topic, func) ->
    topics[topic] = [] if not topics[topic]
    token = generate_token()
    topics[topic].push(token: token, func: func)
    token

  # Unsubscribe from a specific topic, based on a tokenized reference to the
  # subscription.
  lib.unsubscribe = (token) ->
    for topic, subscribers of topics when subscribers?
      for sub, index in subscribers
        token[topic] = subscribers.splice(index,1) # Remove the subscriber
    this

  lib