module Test::Unit::Util::Observable

This is a utility class that allows anything mixing it in to notify a set of listeners about interesting events.



We use this for defaults since nil might mean something

Public Instance Methods

add_listener(channel_name, listener_key=NOTHING) { |value| ... } click to toggle source

Adds the passed proc as a listener on the channel indicated by channel_name. listener_key is used to remove the listener later; if none is specified, the proc itself is used.

Whatever is used as the listener_key is returned, making it very easy to use the proc itself as the listener_key:

listener = add_listener("Channel") { ... }
remove_listener("Channel", listener)
# File test-unit-3.3.4/lib/test/unit/util/observable.rb, line 31
def add_listener(channel_name, listener_key=NOTHING, &listener) # :yields: value
    raise"No callback was passed as a listener")
  key = listener_key
  if (listener_key == NOTHING)
    listener_key = listener
    key =
  channels[channel_name] ||= {}
  channels[channel_name][key] = listener
  return listener_key
notify_listeners(channel_name, *arguments) click to toggle source

Calls all the procs registered on the channel indicated by channel_name. If value is specified, it is passed in to the procs, otherwise they are called with no arguments.

# File test-unit-3.3.4/lib/test/unit/util/observable.rb, line 74
def notify_listeners(channel_name, *arguments)
  channel = channels[channel_name]
  return 0 unless (channel)
  listeners = channel.values
  listeners.each { |listener|*arguments) }
  return listeners.size
remove_listener(channel_name, listener_key) click to toggle source

Removes the listener indicated by listener_key from the channel indicated by channel_name. Returns the registered proc, or nil if none was found.

# File test-unit-3.3.4/lib/test/unit/util/observable.rb, line 51
def remove_listener(channel_name, listener_key)
  channel = channels[channel_name]
  return nil unless (channel)
  key = listener_key
  if (listener_key.instance_of?(Proc))
    key =
  if (channel.has_key?(key))
    return channel.delete(key)
  return nil

Private Instance Methods

channels() click to toggle source
# File test-unit-3.3.4/lib/test/unit/util/observable.rb, line 83
def channels
  @channels ||= {}
  return @channels