gistfile1.rb

class SomeClass < ActiveRecord::Base
  include NumberToCurrency
end

module NumberToCurrency

  def self.included(base)
    base.extend ClassMethods
  end

  module ClassMethods

    def number_to_currency(number, options = {})
      options.symbolize_keys!

      defaults  = I18n.translate('number.format''number.format', :locale => options[:locale], :raise => true) rescue {}
      currency  = I18n.translate('number.currency.format''number.currency.format', :locale => options[:locale], :raise => true)   rescue {}
      defaults  = defaults.merge(currency)

      precision = options[:precision] || defaults[:precision]
      unit      = options[:unit]      || defaults[:unit]
      separator = options[:separator] || defaults[:separator]
      delimiter = options[:delimiter] || defaults[:delimiter]
      format    = options[:format]    || defaults[:format]
      separator = '' if precision == 0

      begin
        format.gsub(/%n/, number_with_precision(number,
          :precision => precision,
          :delimiter => delimiter,
          :separator => separator)
        ).gsub(/%u/, unit)
      rescue
        number
      end
    end
  end
end