Test::Unit::Util::Observable (Module)

In: test/unit/util/observable.rb

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

Constants

NOTHING = "NOTHING/#{__id__}"
  We use this for defaults since nil might mean something

Public Instance methods

add_listener(channel_name, listener_key=NOTHING) {|value| ...}

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)

[Source]

# File test/unit/util/observable.rb, line 29
        def add_listener(channel_name, listener_key=NOTHING, &listener) # :yields: value

          unless(block_given?)
            raise ArgumentError.new("No callback was passed as a listener")
          end
      
          key = listener_key
          if (listener_key == NOTHING)
            listener_key = listener
            key = ProcWrapper.new(listener)
          end
      
          channels[channel_name] ||= {}
          channels[channel_name][key] = listener
          return listener_key
        end
notify_listeners(channel_name, *arguments)

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.

[Source]

# File test/unit/util/observable.rb, line 72
        def notify_listeners(channel_name, *arguments)
          channel = channels[channel_name]
          return 0 unless (channel)
          listeners = channel.values
          listeners.each { |listener| listener.call(*arguments) }
          return listeners.size
        end
remove_listener(channel_name, listener_key)

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

[Source]

# File test/unit/util/observable.rb, line 49
        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 = ProcWrapper.new(listener_key)
          end
          if (channel.has_key?(key))
            return channel.delete(key)
          end
          return nil
        end

[Validate]