Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail From: MRAB Newsgroups: comp.lang.python Subject: Re: pylint woes Date: Wed, 11 May 2016 02:02:01 +0100 Lines: 49 Message-ID: References: <00fa454d-3a62-6282-89dd-d84005db9891@mrabarnett.plus.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: news.uni-berlin.de SBdIAaOQ+aFNxQPOTCdeFgS4UL8Q758MYXaTiRP2ftZg== Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.005 X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'fixed,': 0.09; 'iterate': 0.09; 'example:': 0.10; 'python': 0.10; '100,': 0.16; 'dfs': 0.16; 'from:addr:mrabarnett.plus.com': 0.16; 'from:addr:python': 0.16; 'from:name:mrab': 0.16; 'invalid.': 0.16; 'iterates': 0.16; 'iterator': 0.16; 'list1': 0.16; 'message- id:@mrabarnett.plus.com': 0.16; 'received:192.168.1.4': 0.16; 'received:84.93': 0.16; 'received:84.93.230': 0.16; 'received:io': 0.16; 'received:psf.io': 0.16; 'truncates': 0.16; 'wrote:': 0.16; 'arguments': 0.22; '(like': 0.23; 'bigger': 0.23; 'header:In- Reply-To:1': 0.24; 'header:User-Agent:1': 0.26; "doesn't": 0.26; 'error': 0.27; 'correct': 0.28; 'values': 0.28; 'possibly': 0.32; 'received:84': 0.32; 'point': 0.33; 'lists': 0.34; 'list': 0.34; 'gets': 0.35; 'could': 0.35; 'smaller': 0.36; 'to:addr:python- list': 0.36; 'subject:: ': 0.37; 'being': 0.37; 'beyond': 0.37; 'data': 0.39; 'received:192': 0.39; 'to:addr:python.org': 0.40; 'still': 0.40; 'no.': 0.62; 'matter': 0.63; 'more': 0.63; 'results': 0.66; 'grow': 0.75; '100': 0.79; '102': 0.84; 'enumeration': 0.84 X-CM-Score: 0.00 X-CNFS-Analysis: v=2.1 cv=bsGxfxui c=1 sm=1 tr=0 a=0nF1XD0wxitMEM03M9B4ZQ==:117 a=0nF1XD0wxitMEM03M9B4ZQ==:17 a=L9H7d07YOLsA:10 a=9cW_t1CCXrUA:10 a=s5jvgZ67dGcA:10 a=IkcTkHD0fZMA:10 a=kBpTiQKTDzyPKJuxhDIA:9 a=SmT50CT9l8uubLgb:21 a=tqyXVyzs00ZKss4F:21 a=QEXdDO2ut3YA:10 X-AUTH: mrabarnett@:2500 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.0 In-Reply-To: X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Mailman-Original-Message-ID: <00fa454d-3a62-6282-89dd-d84005db9891@mrabarnett.plus.com> X-Mailman-Original-References: Xref: csiph.com comp.lang.python:108508 On 2016-05-10 23:36, DFS wrote: [snip] > > If lists are still being created: > > * at every moment in time, len(list1) returns a length that doesn't > change even if data is added to the list after the call to len(). > > Example: If the list has 100 items in it at the point len(list) is called: > > for i in range(len(list1)) > > will never iterate more than 100x, no matter how large list1 grows to. > > Caveat: since list1 may be bigger or smaller than the other lists at > that moment in time, an error may occur when using list2[i], list3[i]. > > > Is that all correct as you understand it? > Yes. > > > * at every moment in time, zip(list1, list2, etc) will return a fixed, > same-length lists of tuples, which doesn't change even if data is added > to any of the lists after the call to zip(). > > Example: if the lists have 100, 97 and 102 items in them at the point > zip(lists) is called: > > for item1, item2, item3 in zip(list1, list2, list3) > > will never iterate beyond 97x, even if the lists grow while the > enumeration is occurring. > > Caveat: since zip() possibly truncates lists, the results - the usage of > the data - could be completely invalid. > > > Is that all correct as you understand it? > In Python 2, zip iterates through the arguments immediately and returns a list of tuples, so the answer is yes. In Python 3, zip returns a lazy iterator (like itertools.izip in Python 2) that gets the values from the arguments _on demand_, so the answer is no. [snip]