gistfile1.rb

class User < ActiveRecord::Base
  composed_of :roles, :class_name => 'Array',
              :mapping => %w(roles to_json),
              :constructor => Proc.new { |roles| roles.nil? ? [] : JSON.parse(roles) },
              :converter   => Proc.new { |roles| roles.class == Array ? roles : [] }

  ROLES = [
    'admin',
    'manager',
    'branch_manager',
    'planner',
    'employee',
    'customer'
  ].freeze

  # Define a method for each role: user.admin?, user.manager?, ...
  User.class_eval do
    User::ROLES.each do |role|
      define_method "#{role}?" do
        self.roles.include?(role)
      end
    end
  end
end