status_field.rb

#!/usr/bin/env ruby

module StatusField
  def self.included(base)
    base.extend ClassMethods
  end

  module ClassMethods
    def status_field(*args)
      # Problem: create a class method that returns an array
      # containing all defined status.

      # What I'd like to do:
      # instance_eval { define_method(:status_all) { args } }

      # My silly solution:
      instance_eval %{
        def status_all
          "#{args.join(' ')}".split
        end
      }
    end
  end
end

class Foo
  include StatusField

  status_field :off, :on
end

p Foo.status_all