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; 'python,': 0.02; 'correct.': 0.07; 'incompatible': 0.07; 'string': 0.09; 'escape': 0.09; 'inherited': 0.09; 'literal': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'subject:string': 0.09; 'unrecognized': 0.09; 'python': 0.11; 'language,': 0.12; 'windows': 0.15; 'backslash': 0.16; 'character.': 0.16; 'finney': 0.16; 'formatted': 0.16; 'henry': 0.16; 'literals': 0.16; 'literals.': 0.16; 'received:80.91.229.3': 0.16; 'received:plane.gmane.org': 0.16; 'unambiguous': 0.16; 'language': 0.16; 'programming': 0.22; 'header:User-Agent:1': 0.23; 'error': 0.23; 'documented': 0.24; 'refers': 0.24; 'sort': 0.25; 'right.': 0.26; 'header:X -Complaints-To:1': 0.27; 'chris': 0.29; 'character': 0.29; "doesn't": 0.30; 'writes:': 0.31; 'languages': 0.32; 'text': 0.33; 'url:python': 0.33; 'reader': 0.33; 'but': 0.35; 'there': 0.35; 'really': 0.36; 'url:org': 0.36; 'ben': 0.38; 'url:library': 0.38; 'to:addr:python-list': 0.38; 'anything': 0.39; 'to:addr:python.org': 0.39; 'received:org': 0.40; 'even': 0.60; 'url:3': 0.61; "you're": 0.61; 'such': 0.63; 'needing': 0.65; 'believe': 0.68; 'anything.': 0.68; 'received:125': 0.84; 'url:reference': 0.84; '\xe2\x80\x9cthe': 0.91; 'have.': 0.93 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Ben Finney Subject: Re: Unrecognized backslash escapes in string literals Date: Mon, 23 Feb 2015 13:41:26 +1100 References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Gmane-NNTP-Posting-Host: jigong.madmonks.org X-Public-Key-ID: 0xAC128405 X-Public-Key-Fingerprint: 517C F14B B2F3 98B0 CB35 4855 B8B2 4C06 AC12 8405 X-Public-Key-URL: http://www.benfinney.id.au/contact/bfinney-pubkey.asc X-Post-From: Ben Finney User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.4 (gnu/linux) Cancel-Lock: sha1:6OR3goH+ccYeccZsNND2wqyzw50= 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: 37 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1424659276 news.xs4all.nl 2833 [2001:888:2000:d::a6]:36747 X-Complaints-To: abuse@xs4all.nl Path: csiph.com!usenet.pasdenom.info!bete-des-vosges.org!feed.ac-versailles.fr!nerim.net!novso.com!newsfeed.xs4all.nl!newsfeed2.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail Xref: csiph.com comp.lang.python:86180 Chris Angelico writes: > In Python, unrecognized escape sequences are treated literally, > without (as far as I can tell) any sort of warning or anything. Right. Text strings literals are documented to work that way , which refers the reader to the language reference . > Why is it that Python interprets them this way, and doesn't even give > a warning? Because the interpretation of those literals is unambiguous and correct. It's unfortunate that MS Windows inherited the incompatible “backslash is a path separator”, long after backslash was already established in many programming languages as the escape character. > Is there a way to enable such warnings/errors? A warning or error for a correctly formatted literal with an unambiguous meaning would be an up-Pythonic thing to have. I can see the motivation, but really the best solution is to learn that the backslash is an escape character in Python text string literals. This has the advantage that it's the same escape character used for text string literals in virtually every other programming language, so you're not needing to learn anything unusual. -- \ “The deepest sin against the human mind is to believe things | `\ without evidence.” —Thomas Henry Huxley, _Evolution and | _o__) Ethics_, 1893 | Ben Finney