Class: EventDispatcher::Dispatcher

Inherits:
Object
  • Object
show all
Defined in:
lib/event_dispatcher/dispatcher.rb

Defined Under Namespace

Classes: Listener

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Dispatcher

Returns a new instance of Dispatcher.



5
6
7
 
# File 'lib/event_dispatcher/dispatcher.rb', line 5

def initialize
   @listeners = {}
end

Instance Attribute Details

#listeners ⇒ Object (readonly)

Returns the value of attribute listeners.



3
4
5
 
# File 'lib/event_dispatcher/dispatcher.rb', line 3

def listeners
  @listeners
end

Instance Method Details

#add_listener(event_name, listener, priority = 0) ⇒ Object

Connects a listener to the dispatcher so that it can be notified when an event is dispatched.

Raises:

  • (ArgumentError) 


19
20
21
22
23
24
25
26
 
# File 'lib/event_dispatcher/dispatcher.rb', line 19

def add_listener(event_name, listener, priority = 0)
   raise ArgumentError.new("Priority must be a Fixnum") unless priority.is_a?(Fixnum)
   event_name = symbolize_key(event_name) 
   @listeners[event_name] ||= []
   @listeners[event_name] << Listener.new(listener, priority)

   sort_listeners!(event_name)
end

#dispatch(event_name, event) ⇒ Object

Notifies all listeners of the given event. The event instance is then passed to each listener of that event.



48
49
50
51
52
53
54
55
56
 
# File 'lib/event_dispatcher/dispatcher.rb', line 48

def dispatch(event_name, event)
   event_name = symbolize_key(event_name) 
   return unless @listeners.key?(event_name) && !event.nil?
   @listeners[event_name].each do |l|
      invoke_callable(l.listener, event)  
      # A Listener is able to tell the dispatcher to stop all propagation of the event to future listeners.
      break if event.respond_to?(:stop_propagation) && event.stop_propagation 
   end
end

#has_listeners?(event_name) ⇒ Boolean

Checks if the given event has some listeners that want to listen to.

Returns:

  • (Boolean) 


10
11
12
13
 
# File 'lib/event_dispatcher/dispatcher.rb', line 10

def has_listeners?(event_name)
   event_name = symbolize_key(event_name) 
   @listeners.key?(event_name) && @listeners[event_name].size > 0  ? true : false
end

#remove_listener!(event_name, listener) ⇒ Object

Removes an event listener from the specified event.



29
30
31
32
33
34
35
 
# File 'lib/event_dispatcher/dispatcher.rb', line 29

def remove_listener!(event_name, listener)
   event_name = symbolize_key(event_name) 
   return unless @listeners.key?(event_name) && !listener.nil?
   @listeners[event_name].delete_if { |l| l.listener.eql?(listener) }

   sort_listeners!(event_name)
end

#remove_listeners!(event_name = nil) ⇒ Object

Removes a collection of event listeners attached to a specified event, or reset the entire container of listeners if no event is given.



38
39
40
41
42
43
44
45
 
# File 'lib/event_dispatcher/dispatcher.rb', line 38

def remove_listeners!(event_name = nil)
   if event_name.nil?
      @listeners.clear
   else 
       event_name = symbolize_key(event_name) 
       @listeners.delete(event_name) if @listeners.key?(event_name)
   end
end