module Test::Unit::Util::Observable - test-unit: Ruby Standard Library Documentation

# 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.

### Constants

NOTHING

  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-3.6.7/lib/test/unit/util/observable.rb, line 31
    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) 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-3.6.7/lib/test/unit/util/observable.rb, line 71
    def notify_listeners(channel_name, *arguments)
      channel = channels[channel_name]
      return 0 unless (channel)
      channel.each_value { |listener| listener.call(*arguments) }
      return channel.size
    end

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-3.6.7/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 = ProcWrapper.new(listener_key)
      end
      return channel.delete(key)
    end

### Private Instance Methods

channels() click to toggle source

    # File test-unit-3.6.7/lib/test/unit/util/observable.rb, line 79
    def channels
      @channels ||= {}
      return @channels
    end