Python Exceptions

ifeelfree

·

Follow

Jan 23, 2021

--

Listen

Share

Part 1: What is exception?

• Builtin exceptions

- BaseException
    |----------Exception
                  |-------ArithmeticError
- GeneratorExit
- KeyboardInterupt
- SystemExit 

• Custom exceptions

raise NotImplementedError

Part 2: How to handle exceptions properly?

• treat different types of exception differently (else: actions that will be done if no exceptions occur; final: actions will be taken no matter what kind of exceptions we receive)

def get_restaurant_recommendation(path):
    try:
        config = get_config(path)
        user = config["user"]
    except FileNotFoundException:
        logging.error("VERY UNINFORMATIVE INFORMATION")
        raise
    except JSONDecodeError:
        logging.error("VERY UNINFORMATIVE INFORMATION")
        raise
    except KeyError:
        user = "default_user"
    else:
        pass
    final:
        pass    candidates = get_relevant_restaurants(user)
    pick_best_restaurants(candidates)

• suppress exceptions

try:
   os.remove('somefile.py')
except FileNotFoundError:
   pass OR
from contexlib import suppress
with suppress(FileNotError):
   os.remove('somefile.py')+-- AttributeError```