importer.rb

class Importer
  CODES = {:header, "00F", :data => "00I"}
   
  def self.import_products(fileobj)
    fileobj.lines.each_slice(4).map do |group_lines|
      type, *data_lines = group_lines.map(&:strip)
      case type
      when CODES[:header]
        # what to do/return here?
      when CODES[:data]
        attributes = Hash[[:code, :name, :price].zip(data_lines)]
        Product.create!(attributes)
      else
        fail("Unknown type code: #{type}")
      end
    end.compact
  end
end