Module: Test::Unit::Util::Observable

Module | Test::Unit::Util::Observable
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.

### Methods

add_listener notify_listeners remove_listener

### 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]