Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #52687

Re: Importing variables non-deterministic?

Path csiph.com!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!feeds.phibee-telecom.net!newsfeed.xs4all.nl!newsfeed2.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail
Return-Path <antoon.pardon@rece.vub.ac.be>
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; 'causing': 0.04; 'cpython': 0.05; 'importing': 0.05; 'interpreter': 0.05; 'received:134': 0.05; 'context': 0.07; 'defines': 0.09; 'integers': 0.09; 'overwrite': 0.09; 'segfault.': 0.09; 'so?': 0.09; 'variables.': 0.09; 'python': 0.11; 'behave': 0.16; 'buggy': 0.16; 'caches': 0.16; 'constants.': 0.16; 'equal.': 0.16; 'language)': 0.16; "object's": 0.16; 'protecting': 0.16; 'subject:non': 0.16; 'prevent': 0.16; 'language': 0.16; 'wrote:': 0.18; 'variable': 0.18; 'mechanism': 0.19; 'import': 0.22; 'aug': 0.22; 'header:User-Agent:1': 0.23; 'mon,': 0.24; 'define': 0.26; 'header:In-Reply-To:1': 0.27; 'point': 0.28; 'chris': 0.29; 'am,': 0.29; 'thus': 0.29; "doesn't": 0.30; 'statement': 0.30; 'code': 0.31; 'that.': 0.31; 'constant': 0.31; 'ctypes': 0.31; 'view.': 0.31; 'probably': 0.32; 'definition': 0.35; 'there': 0.35; 'subject:skip:d 10': 0.36; 'subject:?': 0.36; 'changing': 0.37; 'being': 0.38; 'to:addr:python-list': 0.38; 'issue': 0.38; 'does': 0.39; 'to:addr:python.org': 0.39; 'even': 0.60; 'name': 0.63; 'provide': 0.64; 'total': 0.65; 'yes': 0.68; 'safe': 0.72; 'protect': 0.79; 'idiot': 0.84; 'pardon': 0.84; 'preventing': 0.84; '2013': 0.98
X-IronPort-Anti-Spam-Filtered true
X-IronPort-Anti-Spam-Result Ap4EACgHElKGuA9G/2dsb2JhbABbwz2BN4MYAQEEAXgGCwsYCRYPCQMCAQIBRRMGAgKIBgatPYgHkGcWg3wDl2SGFos/gx4
Date Mon, 19 Aug 2013 13:54:43 +0200
From Antoon Pardon <antoon.pardon@rece.vub.ac.be>
User-Agent Mozilla/5.0 (X11; Linux i686; rv:10.0.12) Gecko/20130116 Icedove/10.0.12
MIME-Version 1.0
To python-list@python.org
Subject Re: Importing variables non-deterministic?
References <a75383ec-b363-4ad4-9703-ca5d8ea614df@googlegroups.com> <520f9054$0$30000$c3e8da3$5496439d@news.astraweb.com> <5211C5BD.5040209@rece.vub.ac.be> <kusidq$kaa$1@ger.gmane.org> <5211D464.5090303@rece.vub.ac.be> <CAPTjJmqvzkuZ8Pmux=K6SSPBeLuDQiD99t7g_pAwujCfb2ON4g@mail.gmail.com> <5211DF6C.6030603@rece.vub.ac.be> <CAPTjJmoATrm+Ke5LNu3zJ-2YppBDqOSTXRP+USwNWrpH64r0sQ@mail.gmail.com>
In-Reply-To <CAPTjJmoATrm+Ke5LNu3zJ-2YppBDqOSTXRP+USwNWrpH64r0sQ@mail.gmail.com>
Content-Type text/plain; charset=ISO-8859-1
Content-Transfer-Encoding 7bit
X-BeenThere python-list@python.org
X-Mailman-Version 2.1.15
Precedence list
List-Id General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe <http://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive <http://mail.python.org/pipermail/python-list/>
List-Post <mailto:python-list@python.org>
List-Help <mailto:python-list-request@python.org?subject=help>
List-Subscribe <http://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups comp.lang.python
Message-ID <mailman.26.1376913307.19984.python-list@python.org> (permalink)
Lines 37
NNTP-Posting-Host 2001:888:2000:d::a6
X-Trace 1376913307 news.xs4all.nl 15870 [2001:888:2000:d::a6]:43210
X-Complaints-To abuse@xs4all.nl
Xref csiph.com comp.lang.python:52687

Show key headers only | View raw

Op 19-08-13 11:18, Chris Angelico schreef:
> On Mon, Aug 19, 2013 at 10:03 AM, Antoon Pardon
> <antoon.pardon@rece.vub.ac.be> wrote:
>> This is irrelevant. That some context defines a constant, and that you
>> can use a variable with the same name as a constant in python, doesn't
>> contradict the statement that python (as a language) doesn't has
>> constants. There is nothing in the language that would prevent buggy
>> code from changing any of those variables. So from a python point of
>> views these are just global variables. Just as the struct_global.y was
>> in the original contribution.
> 
> And there's nothing preventing a program from using ctypes to
> overwrite an object's refcount, thus causing a segfault. So?

Yes so? What is your point? Since Cpython caches small integers
there is probably nothing preventing a program from using ctypes
to make the number three behave as the number five. That doesn't
mean that the language define three and five to be equal.

A language having constants, does mean that the language can prevent
a name from being reassigned.

> The issue
> was regarding imports, and it's perfectly safe to import a constant,
> even if the interpreter doesn't protect you from then being a total
> idiot and changing it.

Python doesn't have constants, so you statement about importing a
constant doesn't make sense. The point is that python doesn't provide
the mechanism for protecting names against reassignments. So you
don't know whether the variable you think of as a constant is so
in reality. And this from a pure language definition point of view.
That you can use tools that make the interpreter no longer behave
as the language should, doesn't negate that.

-- 
Antoon Pardon.

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Importing variables non-deterministic? tmellman@googlemail.com - 2013-08-17 07:25 -0700
  Re: Importing variables non-deterministic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-08-17 15:01 +0000
    Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 09:14 +0200
    Re: Importing variables non-deterministic? Dave Angel <davea@davea.name> - 2013-08-19 07:45 +0000
    Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 10:16 +0200
      Re: Importing variables non-deterministic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-08-19 16:57 +0000
        Re: Importing variables non-deterministic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-08-19 17:16 +0000
          Re: Importing variables non-deterministic? Chris Angelico <rosuav@gmail.com> - 2013-08-19 18:25 +0100
        Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 19:40 +0200
    Re: Importing variables non-deterministic? Chris Angelico <rosuav@gmail.com> - 2013-08-19 09:32 +0100
      Re: Importing variables non-deterministic? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-08-19 17:05 +0000
        Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 22:34 +0200
          Re: Importing variables non-deterministic? Steven D'Aprano <steve@pearwood.info> - 2013-08-20 05:48 +0000
            Re: Importing variables non-deterministic? wxjmfauth@gmail.com - 2013-08-19 23:40 -0700
            Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-20 08:55 +0200
              Re: Importing variables non-deterministic? wxjmfauth@gmail.com - 2013-08-20 00:31 -0700
                Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-20 09:55 +0200
                Re: Importing variables non-deterministic? wxjmfauth@gmail.com - 2013-08-20 02:15 -0700
    Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 11:03 +0200
    Re: Importing variables non-deterministic? Chris Angelico <rosuav@gmail.com> - 2013-08-19 10:18 +0100
    Re: Importing variables non-deterministic? Peter Otten <__peter__@web.de> - 2013-08-19 11:49 +0200
    Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 13:54 +0200
    Re: Importing variables non-deterministic? Dave Angel <davea@davea.name> - 2013-08-19 12:33 +0000
    Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 16:55 +0200
    Re: Importing variables non-deterministic? Chris Angelico <rosuav@gmail.com> - 2013-08-19 16:04 +0100
    Re: Importing variables non-deterministic? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-08-19 19:25 +0200
    Re: Importing variables non-deterministic? Ben Finney <ben+python@benfinney.id.au> - 2013-08-20 11:14 +1000

csiph-web