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Exceptions are part of the standard flow control strategy of Python; ex iterators raise StopIteration when exhausted.

Use try/except to catch expected exceptions and do something smart with them; Unexpected exceptions are bug reports.

Signatures:

None

import logging

# standard search for item in items
try:
    something()

except <Expected Exception>:
    logging.<level>("something")    # see [8] for standard levels

except (<Expected Exception 1>, <Expected Exception 2>, <Expected Exception n>):
    pass

except <Expected Exception> as err:
    print("OS error: {0}".format(err))
    logging.exception(err)      # notes

except:
    # DO NOT DO THIS, EVER! [3]
    pass

finally:
    # Always executes [2]
    cleanup()

Examples:

# Simple
config_dict = {}

try:
    print(config_dict['DEFAULT_LOG_LEVEL'])

except KeyError:
    print('Key Error')

# output: 'Key Error'

# Full
try:
    1/0

except ZeroDivisionError as err:
    print('Handling run-time error:', err)  # output: Handling run-time error: division by zero

except Exception as err:
    print(type(err))                        # the exception instance
    print(err.args)                         # arguments stored in .args
    print(err)                              # __str__ allows args to be printed directly
    x, y = err.args                         # unpack args

finally:
    # always executed as last task before try statement completes. eg use for cleanup
    print('Goodbye, world!')

References: