sample.rb

require_dependency 'spree/address'

module AddressExtension
  def self.included(base)
    base.extend(ClassMethods)
    base.send(:include, InstanceMethods)
    base.class_eval do
      unloadable
      attr_accessible :residential


      def full_name
        "#{firstname} #{lastname}"
      end

      def full_address
        [address1, address2, city, state.name, zipcode, country.name].join(" ") rescue ""
      end

    end
  end

  module ClassMethods
  end

  module InstanceMethods
  end
end


Spree::Address.send(:include, AddressExtension)