class User < Person
  has_many :addresses, :foreign_key => 'person_id'
  accepts_nested_attributes_for :addresses
  attr_accessible :addresses_attributes

  has_and_belongs_to_many :categories,
    :readonly => true,
    :join_table => 'categories_elements',
    :foreign_key => 'element_id',
    :association_foreign_key => 'category_id'

  def age
    ((Date.today - self.birthday) / 365).floor
  end
end