Rails polymorphic的使用和理解

class Person < ActiveRecord::Base
  has_one :address, :as => :addressable
end

class Company < ActiveRecord::Base
  has_one :address, :as => :addressable
end

class Address < ActiveRecord::Base
 belongs_to :addressable, :polymorphic => true
end

Address 有adressable_id addressable_type其中，addressable_type可以为Company或者Person