lecture 20 debugging

raising exceptions

stop running the code in this function and move the program execution to the except statement (try & except)

-raise keyword

-call to Exception() function

-a string w/ error message passed to Exception() function

getting the traceback as a string

error message, line # that caused error, sequence of function calls that led to error

what are assertions?

sanity check to make sure code isn’t doing something obviously wrong

“I assert that the condition holds true, and if not, there is a bug somewhere, so immediately stop the program”

assert format

assert ages[0] <= ages[-1]

logging

makes it easy to create a record of custom messages that you write

-messages describe when program execution has reached the logging function call & list any variable you have specified at that point in time

logging module format

import logging

logging.basicConfig(level=logging.DEBUG, format= ‘$(asctime)s - %(levelname)s - %(message)s’)

basicConfig() function

what you want to see, how you want those details displayed

logging.debug()

calls printed out not just string passed to them

-timestamp

DEBUG

don’t debug w/ what function?

print()

logging levels (lowest to highest)

DEBUG, INFO, WARNING, ERROR, CRITICAL

logging.debug()

used for small details; only care about these messages only when diagnosing problems

logging.info()

used to record info on general events in program or confirm that things are working at their point in program

logging.warning()

used to indicate a potential problem that doesn’t prevent the program from working but might do so in the future

logging.error()

used to record an error that caused the program to fail to do something

logging.critical()

used to indicate fatal error that has caused or is about to cause the program to stop running entirely