indecent_exposure.rb

module IndecentExposure
  extend ActiveSupport::Concern

  module ClassMethods
    private
    def expose(name, &block)
      var = "@#{name}"
      define_method(name) do
        instance_variable_set(var, instance_variable_get(var) || instance_eval(&block))
      end
      private(name)
      helper_method name
    end
  end
end