module-class.rb

# ref: https://speakerdeck.com/shioyama/the-ruby-module-builder-pattern?slide=65

class Predicable < Module
  def initialize(*attribute_names)
    @names = attribute_names
  end

  def included(klass)
    @names.each do |name|
      define_method "#{name}?" do
        !!self.instance_variable_get(:"@#{name}")
      end
    end
  end
end

class Article
  include Predicable.new(:draft, :archived)

  def initialize(**state_attributes)
    state_attributes.each do |key, val|
      self.instance_variable_set(:"@#{key}", val)
    end
  end
end