Path: csiph.com!usenet.pasdenom.info!gegeweb.org!usenet-fr.net!nerim.net!novso.com!newsfeed.xs4all.nl!newsfeed2.news.xs4all.nl!xs4all!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 0.004 X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'interpreter': 0.05; 'variables': 0.07; 'attributes': 0.09; 'iac': 0.09; 'sure,': 0.09; 'variable,': 0.09; 'variables.': 0.09; 'python': 0.11; 'change;': 0.16; 'constants.': 0.16; 'enum': 0.16; 'fine.': 0.16; 'from:addr:rosuav': 0.16; 'from:name:chris angelico': 0.16; 'hard- code': 0.16; 'reasonable.': 0.16; 'subject:non': 0.16; 'tradition': 0.16; 'variable.': 0.16; 'wrote:': 0.18; 'meant': 0.20; 'seems': 0.21; '>>>': 0.22; 'example': 0.22; 'import': 0.22; '(in': 0.22; 'aug': 0.22; 'case.': 0.24; 'instance,': 0.24; 'integer': 0.24; 'mon,': 0.24; "i've": 0.25; 'defined': 0.27; 'header:In-Reply-To:1': 0.27; 'function': 0.29; 'am,': 0.29; 'generally': 0.29; 'thus': 0.29; "doesn't": 0.30; 'message- id:@mail.gmail.com': 0.30; 'code': 0.31; 'constant': 0.31; 'everywhere': 0.31; 'class': 0.32; 'probably': 0.32; 'could': 0.34; 'problem': 0.35; 'agree': 0.35; 'classes': 0.35; 'but': 0.35; 'received:google.com': 0.35; 'subject:skip:d 10': 0.36; 'subject:?': 0.36; 'changing': 0.37; 'too': 0.37; 'being': 0.38; 'to:addr:python-list': 0.38; 'does': 0.39; 'to:addr:python.org': 0.39; 'changed': 0.39; 'dave': 0.60; 'more': 0.64; 'dont': 0.67; 'nobody': 0.68; 'fact.': 0.84; "it'd": 0.84; 'pardon': 0.84; 'angel': 0.91; 'avoided.': 0.91; 'hand,': 0.93; '2013': 0.98 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=C8TSa24HaMrs7sZzetxLyVL3r1NVtbTOq672MC0k/oU=; b=gn/SRU7IEd4rMBCSXVYkTICuXZs4IgI28Tso7kU4csAiwnZ5VK+3GCvw2PBmn4B9lc 35KhJEjmDNNmesQHC6B4zEEgC0lShKeAbYlBw3GAJWsqhS0NnZA0iUWI9IOn7dU3leAU foekX3h3YmPeY/ul5qN0bRJQAPp+z8FoOciFOLJqm1BTRzM6k/c6PkncAZtHHgzCiPG/ 1RtNaOAZPkODsHonEeO0EccbQySVgElKujF05qA1CphdjoBYxArXhIjXWLeqgmNtN2AG v7U6VgykAh6vFh0k8jIevE0xLp6lFGesmhuZ4rv20RpvreMVTftkBAxtxVR3YvDgNOxo GpHQ== MIME-Version: 1.0 X-Received: by 10.220.110.202 with SMTP id o10mr12072436vcp.1.1376901173391; Mon, 19 Aug 2013 01:32:53 -0700 (PDT) In-Reply-To: <5211D464.5090303@rece.vub.ac.be> References: <520f9054$0$30000$c3e8da3$5496439d@news.astraweb.com> <5211C5BD.5040209@rece.vub.ac.be> <5211D464.5090303@rece.vub.ac.be> Date: Mon, 19 Aug 2013 09:32:53 +0100 Subject: Re: Importing variables non-deterministic? From: Chris Angelico To: python-list@python.org Content-Type: text/plain; charset=ISO-8859-1 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: 44 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1376901181 news.xs4all.nl 15940 [2001:888:2000:d::a6]:41592 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:52678 On Mon, Aug 19, 2013 at 9:16 AM, Antoon Pardon wrote: > Op 19-08-13 09:45, Dave Angel schreef: >> Antoon Pardon wrote: >>> I think you are overstating your case. Classes and functions are >>> variables too and in general nobody seems to have a problem with them >>> being global. >>> >> >> It's global *variables* that are to be avoided. constants like clsases >> and functions are fine. On the other hand, class attributes can be >> variable, and thus are to be avoided when reasonable. > > Python has no constants. Classes and functions can be changed just like > any other variable. I agree that classes and function are generally > meant to be constant, but often enought so are global int variables. # telnet.py IAC = 0xFF GA = 0xF9 WILL = 0xFB WONT = 0xFC DO = 0xFD DONT = 0xFE # connection.py from telnet import IAC,DO,DONT To be sure, Python won't stop me from changing the value of DONT. But it's a constant, and its value is defined elsewhere (RFC 854). (In this instance, an enum would probably be the better option; but this is an example of a more general case.) In connection.py, I don't care that I've taken a "copy" of the integer 0xFE. It's never going to change; it is a constant in the best tradition of "named number". I could hard-code 0xFE everywhere and the code would work *just fine*, but it'd be less readable, so I don't. Python does have constants. It just doesn't have interpreter support for them. Same as private members, in fact. ChrisA