Daiyue Weng writes: > Hi, I have seen code using try_except with no exceptions, > > from dateutil import parser > > try: > from_date = datetime.datetime.strptime(parameters['from_date'], > '%Y-%m-%d %H:%M:%S.%f') > to_date = datetime.datetime.strptime(parameters['to_date'], > '%Y-%m-%d %H:%M:%S.%f') > except: > from_date = parser.parse(parameters['from_date']) > to_date = parser.parse(parameters['to_date']) > > > I know that such try-catch usage is generally a bad practice, since it > can't locate the root of the exceptions. > > I am wondering how to correct the code above (what it tries to do is > basically trying one processing block, if not working, running another > block of code in except). Also a warning 'Too broad exception clause' > will be generated.
Since help(datetime.strptime) didn't tell, I experimented with datetime.strptime a bit. It seems to raise a ValueError when a string is not formatted according to the pattern or has some component out of range, and TypeError when given a non-string to parse. Tracebacks indicate the exception type. There's no point in catching KeyError, because the except clause would do the same thing again. try: # try with datetime.datetime.strptime ... except (ValueError, TypeError): # try with dateutil.parser.parse ... Also: https://docs.python.org/3/tutorial/errors.html -- https://mail.python.org/mailman/listinfo/python-list
