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

Included in:
TestResult, Test::Unit::UI::TestRunnerMediator
Defined in:
lib/test/unit/util/observable.rb

Overview

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

Constant Summary

NOTHING =

We use this for defaults since nil might mean something

"NOTHING/#{__id__}"

Instance Method Summary (collapse)

Instance Method Details

- (Object) add_listener(channel_name, listener_key = NOTHING, &listener)

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)


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# File '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

- (Object) 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.

--

Perhaps this should be private? Would it ever make sense for an external class to call this method directly?



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# File '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| listener.call(*arguments) }
  return listeners.size
end

- (Object) 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.



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# File '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
  if (channel.has_key?(key))
    return channel.delete(key)
  end
  return nil
end