2021-05-20

daily note

  • Daily Log:

    • How to Handle Exceptions

      • Metadata:

        • #article #programming #python

      • A typical flow may require several services and anyone of the services can break and interrupt the flow

      • Instead of writing a pattern that is repeated try-except with every service like creating a class and creating a function that logs all the different errors

        • Which is hard to maintain and is focused on writing the errors

      • Make exceptions specific

        • raise specific errors instead of raising generic exception
        try:
  order_status = status_service.get_order_status(order_id)
except Exception as e:
  logger.exception("...{e}...")
  raise e

      • Mind your own business

        • Don’t teach classes what can go wrong, instead have multiple classes to handle each thing and then use a single try…except… block
        • Don’t have to re-raise errors, just use raise
        class StatusService:
  def get_order_status(order_id):
    try:
      pass
    except:
      raise CustomError() from e

class ReceiptService:
  def create(order_id):
    try:
      pass
    except:
      raise ReceiptGenerationFailed() from e

class OrderService:
  def emit(self, order_id: str) -> dict:
    try:
      # all the services in here
    except OrderNotFound as e:
      # handle this
    except ReceiptGenerationFailed as e:
      # handle this
        • Better logging
          • Tell don’t ask
          • logging exceptions shouldn’t need to pass the exception because it is already implicit
          • Let the downstream exception class to log the exact message
          • Catching and raising exceptions effectively
            • Instead of catching and re-raising, according to PEP3134 it is enough to just plainly raise or raising from another exception
          • Logging exceptions effectively
            • Don’t log the exception object, use logging.exception function to handle the stack trace

  • Retrospective::

  • Daily Stoic::

    • When it comes to learning focus on quality over quantity, you will never read all the literature available in the world but you can benefit from reading from a few