Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!eternal-september.org!feeder.eternal-september.org!feeds.phibee-telecom.net!newsfeed.xs4all.nl!newsfeed3.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 0.049 X-Spam-Evidence: '*H*': 0.90; '*S*': 0.00; 'skip:[ 20': 0.04; 'syntax': 0.04; 'skip:> 40': 0.09; 'subject:while': 0.09; 'clayton': 0.16; 'email addr:python.org]': 0.16; 'finney': 0.16; 'repetition,': 0.16; 'true:': 0.16; 'zero,': 0.16; 'thursday,': 0.16; 'bit': 0.19; 'message-----': 0.19; 'thoughts': 0.19; 'seems': 0.21; 'this?': 0.23; 'url:moin': 0.24; "i've": 0.25; 'extension': 0.26; 'header:In-Reply-To:1': 0.27; 'to:2**1': 0.27; 'generally': 0.29; 'url:mailman': 0.30; 'url:wiki': 0.31; 'writes:': 0.31; 'url:python': 0.33; 'common': 0.35; 'december': 0.35; 'skip:s 30': 0.35; 'something': 0.35; 'there': 0.35; 'skip:> 10': 0.36; 'url:listinfo': 0.36; 'url:org': 0.36; 'email addr:python.org': 0.37; 'ben': 0.38; 'to:addr:python-list': 0.38; 'that,': 0.38; 'use.': 0.39; 'to:addr:python.org': 0.39; 'url:mail': 0.40; 'skip:u 10': 0.60; 'break': 0.61; 'url:3': 0.61; 'received:173': 0.61; 're:': 0.63; 'email name:python-list': 0.65; 'received:phx3.secureserver.net': 0.65; 'received:prod.phx3.secureserver.net': 0.65; 'header:Reply-To:1': 0.67; 'reply-to:no real name:2**0': 0.71; 'empire': 0.84; 'subject:Extension': 0.84; 'received:173.201': 0.91; 'received:173.201.192': 0.91 From: "Clayton Kirkwood" To: "'Ben Finney'" , References: <14d2b880-3837-4267-a769-33ae7393f78b@googlegroups.com> <857fxxfv9u.fsf@benfinney.id.au> In-Reply-To: <857fxxfv9u.fsf@benfinney.id.au> Subject: RE: Extension of while syntax Date: Thu, 11 Dec 2014 18:59:20 -0800 MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Mailer: Microsoft Office Outlook 12.0 thread-index: AdAVtL6ca9oFt+FLSZenBFxlerQHVgAAktoA Content-Language: en-us X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 Precedence: list Reply-To: crk@godblessthe.us 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: 60 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1418353190 news.xs4all.nl 2903 [2001:888:2000:d::a6]:38090 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:82408 I would prefer: while value =3D initial_value in undesired_values: value =3D get_some_value() Seems I've seen something like this before, C, Perl? Clayton >-----Original Message----- >From: Python-list [mailto:python-list- >bounces+crk=3Dgodblessthe.us@python.org] On Behalf Of Ben Finney >Sent: Thursday, December 11, 2014 6:38 PM >To: python-list@python.org >Subject: Re: Extension of while syntax > >Nelson Crosby writes: > >> I was thinking a bit about the following pattern: >> >> value =3D get_some_value() >> while value in undesired_values: >> value =3D get_some_value() > >I think that's an anti-pattern (because of the repetition, as you say). > >An improvement:: > > value =3D some_default_value_such_as_None > while value in undesired_values: > value =3D get_some_value() > >More common and generally useful:: > > while True: > value =3D get_some_value() > if value not in undesired_values: > break > >> What are other's thoughts on this? > >I think there are already clean ways to deal with this in common use. > > >continue-statements-and-else-clauses-on-loops> > >-- > \ =E2=80=9C=E2=80=A6 one of the main causes of the fall of the = Roman Empire was | > `\ that, lacking zero, they had no way to indicate successful = | >_o__) termination of their C programs.=E2=80=9D = =E2=80=94Robert Firth | >Ben Finney > >-- >https://mail.python.org/mailman/listinfo/python-list