Event Handler for ruby

eventhandler.rb

# coding: utf-8

class EventHandler

  def initialize
    @methods = []
  end

  def add(method)
    if !@methods.include?(method)
      @methods << method
    end
    return self
  end
  alias << add

  def delete(method)
    if @methods.include?(method)
      @methods.delete method
    end
    return self
  end

  def notify(*args)
    @methods.dup.each do|method|
      # dupしてるのは，呼び出した先でこのイベントハンドラに登録されるとeachがおかしくなるため．
      method.call(*args)
    end
  end

end

if $0 == __FILE__

  class ClassA

    attr_reader :event

    def initialize
      @event = EventHandler.new
    end

    def some_event
      @event.notify
    end

  end

  class ClassB

    def initialize class_a
      class_a.event << method(:class_a_event)
    end

    def class_a_event
      puts "event is handled"
    end

  end

  class_a = ClassA.new
  class_b = ClassB.new(class_a)

  class_a.some_event

end