2021-05-20

• 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::

  • One week ago: [[May 13th, 2021]]
  • One month ago: [[April 20th, 2021]]
  • One quarter ago: [[February 20th, 2021]]
  • One year ago: [[May 20th, 2020]]

• 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