Mega Code Archive
Coupling Systems Loosely with Callbacks
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class MyObject
def initialize
setup_listeners
end
def produce_widget(color)
notify(:new_widget, color)
end
def setup_listeners
@EventDispatcher_listeners = {}
end
def subscribe(event, &callback)
(@EventDispatcher_listeners[event] ||= []) << callback
end
def notify(event, *args)
if @EventDispatcher_listeners[event]
@EventDispatcher_listeners[event].each do |m|
m.call(*args) if m.respond_to? :call
end
end
return nil
end
end
class MyObjectObserver
def initialize(factory)
@counts = Hash.new(0)
factory.subscribe(:new_widget) do |color|
@counts[color] += 1
puts "#{@counts[color]} #{color} widget(s) created."
end
end
end
f1 = MyObject.new
MyObjectObserver.new(f1)
f1.produce_widget("red")
f1.produce_widget("green")
f1.produce_widget("red")
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