imageable_with_private_methods.rb

class Imageable < Module
  def initialize(has_one: %i(main_image))
    has_one.each { |image_kind| define_image_getter(image_kind) }
  end

  private

  def included(model_class)
    model_class.has_many :images
  end

  def define_image_getter(image_kind)
    define_method image_kind do
      images.find_by(kind: image_kind)
    end
  end
end