Path: csiph.com!news.swapon.de!fu-berlin.de!uni-berlin.de!not-for-mail From: Random832 Newsgroups: comp.lang.python Subject: Re: argparse: use of double dash to separate options and positional arguments Date: Fri, 06 Nov 2015 16:56:50 -0500 Lines: 31 Message-ID: References: <20151106100743.GN3685@isis.luna> Mime-Version: 1.0 Content-Type: text/plain X-Trace: news.uni-berlin.de UXBS0AJ9X5I/p53WWTwmVALmLKlW/WLD2MtM3roH907g== Cancel-Lock: sha1:BA3Kw1wtCi6hrjtVbBeXDfOxXR4= Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.000 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'args': 0.04; 'caller': 0.07; 'convention.': 0.07; 'interpreted': 0.07; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'script,': 0.09; 'second.': 0.09; 'terminator': 0.09; 'python': 0.10; 'argument': 0.15; "(it's": 0.16; 'argument.': 0.16; 'received:80.91.229.3': 0.16; 'received:io': 0.16; 'received:plane.gmane.org': 0.16; 'received:psf.io': 0.16; 'ssh,': 0.16; 'subject:argparse': 0.16; 'subject:options': 0.16; 'shell': 0.18; 'arguments': 0.22; 'setup,': 0.22; 'pass': 0.22; 'script': 0.25; 'header:User- Agent:1': 0.26; 'header:X-Complaints-To:1': 0.26; 'processed': 0.27; 'said,': 0.27; 'arguments,': 0.29; "i'm": 0.30; 'another': 0.32; 'options': 0.33; 'foo': 0.33; 'received:comcast.net': 0.33; 'skip:- 10': 0.34; 'list': 0.34; 'attempt': 0.35; 'subject:use': 0.35; 'something': 0.35; 'skip:p 30': 0.35; 'should': 0.36; 'to:addr:python-list': 0.36; 'subject:: ': 0.37; 'two': 0.37; 'being': 0.37; 'say': 0.37; 'received:org': 0.37; 'list.': 0.37; 'delete': 0.38; 'skip:p 20': 0.38; 'files': 0.38; 'sure': 0.39; 'does': 0.39; 'rather': 0.39; 'to:addr:python.org': 0.40; 'where': 0.40; 'some': 0.40; 'as:': 0.79; 'one;': 0.84; 'otten': 0.84; 'safer': 0.91 X-Injected-Via-Gmane: http://gmane.org/ X-Gmane-NNTP-Posting-Host: c-68-39-146-59.hsd1.in.comcast.net User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.20+ Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Xref: csiph.com comp.lang.python:98374 Peter Otten <__peter__@web.de> writes: > I'm not sure about this one; one purpose of REMAINDER is to pass on the > unprocessed arguments to another program/script, and this might follow the > same convention. Should > > parser.add_argument('-v', '--verbose', action='store_true') > parser.add_argument('cmd_args', nargs=argparse.REMAINDER) > args = parser.parse_args() > subprocess.call(["rm"] + args.cmd_args) > > $ my_prog -v -- -r foo > > attempt to delete two files "-r" and "foo" or remove the "foo" directory? > The first is the safer alternative, and as you say stripping the "--" is > easy. I think it should be the second. If the caller wants it to be treated as a list of files rather than a list of arguments, it should be using subprocess.call(["rm", "--"] + args.cmd_args). The purpose is, as you said, to pass the *unprocessed* argument. -- has been processed by being interpreted as a terminator for the argument list. I have a script (it's a shell script, not a python script) where I actually do something similar... it does some setup, then calls ssh. If I want to pass some options directly to ssh, I call it as: "scriptname -script-option -- -ssh-option remote-command"