require "rails"
  class Tour
      include Rails::Initializable

      attr_reader :cities
      
      def initialize
        @cities = []
      end
  end
  
  ###一开始的计划是：先去USA，再去Britain，最后去France，
  Tour.initializer("USA") do |do_the_same_th|
      @cities << { country: "USA", city: "Silicon Valley", do: do_the_some_th }
  end
  
  Tour.initializer("France", before: "Britain") do |do_the_same_th|
      @cities << { country: "France", city: "Paris", do: do_the_same_th }
  end
  
  Tour.initializer("Britain", before: "USA") do |do_the_same_th|
      @cities << { country: "Britain", city: "London", do: do_the_same_th }
  end
  
  ###后来我改变注意了，想去英国后，先回趟中国，再去法国
  Tour.initializer("China", before: "Britain", after: "France") do |do_the_same_th|
      @cities << { country: "China", city: "Beijin", do: do_the_same_th }
  end
  
  my_tour = Tour.new
  my_tour.run_initializers(:default, "take a photo")
  
  my_tour.cities.each_with_index do |tour, index|
    p "#{index}: Went to #{tour[:country]}-#{tour[:city]} and #{tour[:do_the_same_th]}"
  end