# File 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] ||= Hash.new channels[channel_name][key] = listener return listener_key end