On Fri, Feb 21, 2014 at 8:12 AM, Chris Angelico <ros...@gmail.com> wrote: > On Sat, Feb 22, 2014 at 1:50 AM, Antoine Pitrou <solip...@pitrou.net> wrote: >> On Sat, 22 Feb 2014 00:28:01 +1000 >> Nick Coghlan <ncogh...@gmail.com> wrote: >>> >>> Neither of these objections addresses the problems with the status quo, >>> though: >>> >>> - the status quo encourages overbroad exception handling (as >>> illustrated by examples in the PEP) >> >> I don't get this. Using the proper exception class in a "try...except" >> suite is no more bothersome than using the proper exception class in >> this newly-proposed construct. > > Overbroad exception handling comes in two ways. One is simply catching > Exception or BaseException when a narrower class would be better, and > that's not addressed by this PEP (except insofar as it does not have a > bare "except:" syntax, and so it forces you to at least be explicit > about catching BaseException). The other is this: > > try: > f(x[i]) > except IndexError: > f(default) > > Translating that into this form: > > f(x[i] except IndexError: default) > > means that an IndexError thrown inside f() will not be caught. While > it is, of course, possible to write that currently: > > try: > arg = x[i] > except IndexError: > arg = default > f(arg) > > it's that much less readable, and as evidenced by several examples in > the standard library (some of which are in the PEP, and a few more can > be found in my associated collection [1]), it's common to short-cut > this. By providing a clean and convenient syntax for catching an > exception in just one small expression, we encourage the narrowing of > the catch front.
Be sure to capture in the PEP (within reason) a summary of concerns and rebuttals/acquiescence. Eli's, Brett's, and Antoine's concerns likely reflect what others are thinking as well. The PEP and its result will be better for recording such matters. In fact, that's a key goal of PEPs. :) -eric _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
