gistfile1.rb

class PhoneNumber < ActiveRecord::Base
  belongs_to :phonable, :polymorphic => true
  validates :number,    :length => { :minimum => 10, :maximum => 12}
  validates_length_of   :area_code, :is => 3  #  205
  validates_length_of   :prefix,    :is => 3  #  867
  validates_length_of   :line,      :is => 4  # 5309

  def number=(val)
    val.gsub! /[^\d]/, '' # Prune dashes, parenthesis, etc
    self.area_code, self.prefix, self.line = val.scan( /(\d{3})(\d{3})(\d{4})/ ).flatten
    write_attribute(:number, val)
  end
end