Path: csiph.com!usenet.pasdenom.info!news.albasani.net!newsfeed.freenet.ag!news2.euro.net!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.001 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'scripts': 0.03; 'explicitly': 0.05; 'default.': 0.09; 'option,': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'subject:Why': 0.09; 'subject:module': 0.09; 'jan': 0.12; '(do': 0.16; 'belongs': 0.16; 'command-line': 0.16; 'make,': 0.16; 'ought': 0.16; 'really?': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'reedy': 0.16; 'subject:argparse': 0.16; 'exception': 0.16; 'wrote:': 0.18; 'library': 0.18; 'bit': 0.19; 'app': 0.19; 'module': 0.19; '>>>': 0.22; 'code,': 0.22; 'header:User-Agent:1': 0.23; 'config': 0.24; "shouldn't": 0.24; 'tracker': 0.26; 'header:X-Complaints-To:1': 0.27; 'header:In-Reply-To:1': 0.27; 'am,': 0.29; 'raise': 0.29; 'easier': 0.31; 'app.': 0.31; "d'aprano": 0.31; 'libraries': 0.31; 'steven': 0.31; 'framework': 0.33; 'subject:the': 0.34; 'could': 0.34; 'agree': 0.35; 'no,': 0.35; 'but': 0.35; 'subject:?': 0.36; 'should': 0.36; 'application': 0.37; 'turn': 0.37; 'to:addr :python-list': 0.38; 'issue': 0.38; 'pm,': 0.38; 'to:addr:python.org': 0.39; 'received:org': 0.40; 'catch': 0.60; 'received:173': 0.61; 'more': 0.64; 'comment.': 0.84; 'ethan': 0.84; 'furman': 0.84; 'ok?': 0.84; 'received:fios.verizon.net': 0.84; 'rusi': 0.91; 'responses': 0.93; '2013': 0.98 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Terry Reedy Subject: Re: Why is the argparse module so inflexible? Date: Sat, 29 Jun 2013 00:37:23 -0400 References: <51CC42E3.3070508@gmail.com> <51ccc190$0$29999$c3e8da3$5496439d@news.astraweb.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: pool-173-75-251-66.phlapa.fios.verizon.net User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130620 Thunderbird/17.0.7 In-Reply-To: X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 31 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1372480662 news.xs4all.nl 15895 [2001:888:2000:d::a6]:52091 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:49404 On 6/29/2013 12:12 AM, rusi wrote: > On Saturday, June 29, 2013 7:06:37 AM UTC+5:30, Ethan Furman wrote: >> On 06/27/2013 03:49 PM, Steven D'Aprano wrote: >>> [rant] >>> I think it is lousy design for a framework like argparse to raise a >>> custom ArgumentError in one part of the code, only to catch it elsewhere >>> and call sys.exit. At the very least, that ought to be a config option, >>> and off by default. >>> >>> Libraries should not call sys.exit, or raise SystemExit. Whether to quit >>> or not is not the library's decision to make, that decision belongs to >>> the application layer. Yes, the application could always catch >>> SystemExit, but it shouldn't have to. >> >> >> So a library that is explicitly designed to make command-line scripts easier >> and friendlier should quit with a traceback? >> >> Really? > > So a library that behaves like an app is OK? No, Steven is right as a general rule (do not raise SystemExit), but argparse was considered an exception because its purpose is to turn a module into an app. With the responses I have seen here, I agree that this is a bit short-sighted, as inflexible behavior. The tracker issue could use more review and comment. -- Terry Jan Reedy