Emittr is a event emitter for Ruby.

Add this line to your Gemfile:

gem 'emittr'

Or install it yourself as:

$ gem install emittr

Emittr can be used in two ways. You can just create an Emittr::Emitter instance and use it to emit and listen to events, like this:

emitter = Emittr::Emitter.new

emitter.on :user_connected do |user_name|
  puts "Hello, #{user_name}"
end

emitter.emit :user_connected, 'Mr. Anderson'

Or you can include the Emittr::Events module into an existent class to make it an event emitter:

class Server
  include Emittr::Events

  def initialize
    on(:user_connected) do |user_data|
      handle_new_connection(user_data)
    end
  end

  def handle_new_connection(user_data)
    # do something clever here
  end
end

server = Server.new

server.emit :user_connected, { name: 'Somebody', ip: '127.0.0.1' }

You can set a limit to prevent adding listeners by using:

class Server
  include Emittr::Events

  max_listeners 20
end

or

emitter = Emittr::Emitter.new max_listeners: 20

This value can be get later from #max_listeners_value.

NOTE: You can't overwrite #max_listeners value. If you try to do it, a RuntimeError will be raised.

• #on(event, callback) - Call callback when event is emitted.

• #once(event, callback) - Call callback when event is emitted for the first time, then the callback is removed from the listeners list of the given event.

• #on_any(callback) - Call callback whenever an event is emitted.

• #once_any(callback) - Call callback the first time any event is emitted then removes it from list.

• #on_many_times(event, times, callback) - Acts like #once, but the listener will be removed from the list only after emitting the event as many times as provided. It accepts only positive Integer number as argument.

• #off(event, callback) - Remove callback from event callbacks list.

• #off(event) - Removes all callbacks for event.

• #off - Removes all callbacks for all events.

• #off_any(callback) - Remove callback from list to be run after any event is emitted.

• #emit(type, *args) - Emit an event with all passed args as params.

• #listeners_for(event) - Return all callbacks for event. Callbacks added with #on_any or #once_any will not be included.

• #listeners_for_any - Return all callbacks added with #on_any or #once_any

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

The gem is available as open source under the terms of the MIT License.