Add functions to a rails activerecord model dynamically for testing role membership

dynamic_roles.rb

class User < ActiveRecord::Base

  #available roles for users
  ROLES = ['uber', 'admin', 'mod']
  
  #generates methods like user.admin? for testing whether the user belongs to
  #the proper role
  ROLES.each do |role_name|
    self.send(:define_method, "#{role_name}?".to_sym) { self.role == role_name }
  end