class Article < ActiveRecord::Base
  STATES = %w(review published)
  validates :state, :inclusion => {:in => STATES}

  STATES.each do |state|
    define_method "#{state}?" do
      self.state == state
    end
  end

  class << self
    STATES.each do |state|
      define_method "#{state}" do
        state
      end
    end
  end
end

@article.state = State.find_by_name("published")

@article.state = State.published

@article.state = Article.published

class MyClass
  class << self
    def my_method
      puts 'this is a method'
    end
  end
end

class MyClass
  def self.my_method
    puts 'this is a method'
  end
end