Class: AMQP::Events::Event

Inherits:
Object
  • Object
show all
Defined in:
lib/amqp-events/event.rb

Overview

Represent Event that can be subscribed to (by subscribers/observers) All subscribed observers will be called when this Event ‘fires’.

TODO: Mutexes to synchronize @subscribers update/event fire ? github.com/snuxoll/ruby-event/blob/master/lib/ruby-event/event.rb TODO: Meta-methods that allow Events to fire on method invocations: github.com/nathankleyn/ruby_events/blob/85f8e6027fea22e9d828c91960ce2e4099a9a52f/lib/ruby_events.rb TODO: Add exception handling and subscribe/unsubscribe notifications: github.com/matsadler/rb-event-emitter/blob/master/lib/events.rb

Direct Known Subclasses

ExternalEvent

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(host, name) ⇒ Event

Returns a new instance of Event.



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# File 'lib/amqp-events/event.rb', line 27

def initialize(host, name)
  @host = host
  @name = name.to_sym
  @subscribers = {}
end

Instance Attribute Details

#host ⇒ Object (readonly)

Returns the value of attribute host.



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# File 'lib/amqp-events/event.rb', line 24

def host
  @host
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/amqp-events/event.rb', line 24

def name
  @name
end

#subscribers ⇒ Object (readonly) Also known as: listeners

Returns the value of attribute subscribers.



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# File 'lib/amqp-events/event.rb', line 24

def subscribers
  @subscribers
end

Class Method Details

.create(host, name, opts = {}, &block) ⇒ Object

Creates Event of appropriate subclass, depending on arguments



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# File 'lib/amqp-events/event.rb', line 19

def create host, name, opts={}, &block
  opts.empty? ? Event.new(host, name, &block ) : ExternalEvent.new(host, name, opts, &block)
end

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/amqp-events/event.rb', line 88

def == (other)
  case other
    when Event
      super
    when nil
      @subscribers.empty?
    else
      false
  end
end

#clear ⇒ Object

Clears all the subscribers for a given Event



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# File 'lib/amqp-events/event.rb', line 84

def clear
  @subscribers.clear
end

#fire(*args) ⇒ Object Also known as: call

TODO: make fire async: just fire and continue, instead of waiting for all subscribers to return, as it is right now. AMQP callbacks and EM:Deferrable?



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# File 'lib/amqp-events/event.rb', line 71

def fire(*args)
  @subscribers.each do |key, subscriber|
    subscriber.call *args
  end
end

#subscribe(*args, &block) ⇒ Object Also known as: listen, +

You can subscribe anything callable to the event, such as lambda/proc, method(:method_name), attached block or a custom Handler. The only requirements, it should respond to a #call and accept arguments given to Event#fire.

You can give optional name to your subscriber. If you do, you can later unsubscribe it using this name. If you do not give subscriber a name, it will be auto-generated using its #name method and uuid.

You can unsubscribe your subscriber later, provided you know its name.

:call-seq:

event.subscribe("subscriber_name", proc{|*args| "Subscriber 1"})
event.subscribe("subscriber_name", method(:method_name))
event.subscribe(method(:method_name) # Implicit subscriber name == :method_name
event.subscribe("subscriber_name") {|*args| "Named subscriber block" }
event += method(:method_name)  # C# compatible syntax, just without useless "delegates"



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# File 'lib/amqp-events/event.rb', line 50

def subscribe(*args, &block)
  subscriber = block ? block : args.pop
  name = args.empty? ? generate_subscriber_name(subscriber) : args.first.to_sym

  raise HandlerError.new "Handler #{subscriber.inspect} does not respond to #call" unless subscriber.respond_to? :call
  raise HandlerError.new "Handler name #{name} already in use" if @subscribers.has_key? name
  @subscribers[name] = subscriber

  self # This allows C#-like syntax : my_event += subscriber
end

#unsubscribe(name) ⇒ Object Also known as: remove, -

Unsubscribe existing subscriber by name



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# File 'lib/amqp-events/event.rb', line 62

def unsubscribe(name)
  raise HandlerError.new "Unable to unsubscribe handler #{name}" unless @subscribers.has_key? name
  @subscribers.delete(name)

  self # This allows C#-like syntax : my_event -= subscriber
end