Trying to figure out why I'm having to manually require a class that is within the same namespace inside of Rails.

1_nickel.rb

# located in lib/pumper/nickel.rb

# the only way Back.setup works inside of #add_crappy_music
# is if I add the following:
# require "pumper/nickel/back"
#
# Why?
module Pumper
  class Nickel < ActiveRecord::Base
    def add_crappy_music
      # called within a different class in a different namespace
      # this call causes undefined method `setup' for Back:Class
      Back.setup
      # does not work when calling Pumper::Nickel::Back.setup either
    end
  end
end

2_back.rb

module Pumper
  class Nickel < ActiveRecord::Base
    class Back < ActiveRecord::Base
      def setup
        puts "whining"
      end
    end
  end
end

3_back_creator.rb

# located in app/services/thing/back_creator.rb

module Thing
  class BackCreator
    def run
      nickel = Pumper::Nickel.new
      nickel.add_crappy_music # the failing call originates here
    end
  end
end

4_iron.rb

# located in app/models/iron.rb

class Iron < ActiveRecord::Base
  # irrelevant
end

Before anybody asks, /lib is in my config.autoload_paths.