Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder1.news.weretis.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.xs4all.nl!newsfeed2a.news.xs4all.nl!xs4all!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; 'python,': 0.02; 'anyway.': 0.05; 'say,': 0.05; 'assign': 0.07; 'bits': 0.09; 'literal': 0.09; 'pointers': 0.09; 'references.': 0.09; 'cc:addr:python-list': 0.11; 'python': 0.11; 'def': 0.12; 'suggest': 0.14; "wouldn't": 0.14; 'behaviour.': 0.16; 'bytecode': 0.16; 'cases)': 0.16; 'created;': 0.16; 'else"': 0.16; 'tuple': 0.16; 'wrote:': 0.18; 'wed,': 0.18; 'thu,': 0.19; 'seems': 0.21; 'feb': 0.22; 'cc:addr:python.org': 0.22; 'alternate': 0.24; "aren't": 0.24; 'either.': 0.24; 'cc:2**0': 0.24; 'possibly': 0.26; 'header:In- Reply-To:1': 0.27; 'chris': 0.29; 'am,': 0.29; "doesn't": 0.30; 'forgot': 0.30; 'message-id:@mail.gmail.com': 0.30; 'another': 0.32; "i'd": 0.34; 'could': 0.34; "can't": 0.35; 'created': 0.35; 'something': 0.35; 'but': 0.35; 'received:google.com': 0.35; 'really': 0.36; 'yield': 0.36; 'list': 0.37; 'whatever': 0.38; 'pm,': 0.38; 'that,': 0.38; 'most': 0.60; 'new': 0.61; "you're": 0.61; 'places': 0.64; 'more': 0.64; 'to:addr:gmail.com': 0.65; 'anything.': 0.68; 'to,': 0.72; '2015': 0.84; 'otten': 0.84; '1:18': 0.91; 'notion': 0.91 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type; bh=eKh4zIYyZTI/X9l4vtp8lPQU8rvdR9XoK2wiG0/Z6Y4=; b=UBNLkmm9kF+w0ITx9XV63YTml+rXdxdYUOd29d2OXQy9yJMF7g38O+F1zPS2r0NwLL tD0dGNmA16jkO2OnLArs3SyFU5xCQxxijWHRA+rkyRCHTM7UvBwSvtXr429xSQDUQwiL Ft2i87ey+sK2ufXEOPsqSil4Od25VRP9+dsMrO6PVWbtThV4bGWqYBNbNetwSPBWHdBC LX15Ah4SRTpIreJriDJ7wU60pzAuR84U6rnVs0GvtWS3NwduNBTbVBmdMBr3iJyPXVYq fSRQXpJkUl2zwUyej//mCaF08yxPfGCOt7O4hNDtKEeTr22ashNJIZGLNYD2GvYJySK+ Ek3w== X-Received: by 10.229.114.74 with SMTP id d10mr6204694qcq.5.1423127449564; Thu, 05 Feb 2015 01:10:49 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: <07f4498c-7917-4315-85d4-73283a830f2d@googlegroups.com> From: Devin Jeanpierre Date: Thu, 5 Feb 2015 01:10:09 -0800 Subject: Re: meaning of: line, = To: Chris Angelico Content-Type: text/plain; charset=UTF-8 Cc: "python-list@python.org" 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: 34 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1423127457 news.xs4all.nl 2833 [2001:888:2000:d::a6]:52822 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:85252 On Wed, Feb 4, 2015 at 1:18 PM, Chris Angelico wrote: > On Thu, Feb 5, 2015 at 4:36 AM, Peter Otten <__peter__@web.de> wrote: >> Another alternative is to put a list literal on the lefthand side: >> >>>>> def f(): yield 42 >> >> ... >>>>> [result] = f() >>>>> result >> 42 > > Huh, was not aware of that alternate syntax. Nor are most people. Nor is Python, in some places -- it seems like people forgot about it when writing some bits of the grammar. I'd suggest not using it. >> (If you're worried: neither the list nor the tuple will be created; the >> bytecode is identical in both cases) > > It can't possibly be created anyway. Python doesn't have a notion of > "assignable thing that, when assigned to, will assign to something > else" like C's pointers or C++'s references. There's nothing that you > could put into the list that would have this behaviour. C pointers don't do that either. It's really just references. (C pointers aren't any more action-at-a-distance than Python attributes.) Anyway, it could create a new list in Python, because Python can do whatever it wants. But it doesn't, because as you say, that wouldn't do anything. -- Devin