complete_order.rb

class CompleteOrder
  def perform
    notify_recipient(order.recipient)
    update_inventory(order.item_number)
    prepare_shippping(order.shipping_address)
  end
  
  private
  
  def order
    # cache the query for order as an instance variable
    # since it is accessed multiple times in the #perform method
    @order ||= Order.find_by(id: @order_id)
  end
end