Address decorator extracted from a project

gistfile1.rb

require 'delegate'

module ConcatHelper
  def concat(*elements, separator)
    elements.reject(&:blank?).join(separator)
  end

  def format(format_string, string)
    format_string % string unless string.blank?
  end
end

class AddressTemplate < SimpleDelegator
  include ConcatHelper

  def to_s
    display_address
  end

  private

  alias address __getobj__

  def display_address
    return '' unless address

    number_complement   = concat(number, complement, ' ')
    city_state          = concat(city, state, ' / ')
    district_city_state = concat(district, city_state, ' - ')

    concat(street, number_complement, district_city_state, ', ')
  end

  def number
    format 'Nº %s', address.number
  end

  def complement
    format '(%s)', address.complement
  end
end