gistfile1.rb

module States

  STATES = %w(cancelled declined passive active approved pending flagged complete)
  attr_accessor :state # remove this if using an activerecord column

  def self.included(mod)
    STATES.each do |state|
      up_state = state.upcase
      mod.const_set(up_state, state)
      mod.send(:define_method, state+'?') do
        self.state == state
      end
    end
  end

end

irb(main):017:0> class A; include States; end
irb(main):018:0> a=A.new; a.state = A::CANCELLED
=> "cancelled"
irb(main):019:0> a.cancelled?
=> true
irb(main):020:0> a.declined?
=> false