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

Groups > comp.lang.python > #19769

Re: copy on write

Path csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!aioe.org!news.stack.nl!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail
Return-Path <jeanpierreda@gmail.com>
X-Original-To python-list@python.org
Delivered-To python-list@mail.python.org
X-Spam-Status OK 0.050
X-Spam-Evidence '*H*': 0.90; '*S*': 0.00; '>>>>': 0.09; 'cc:addr :python-list': 0.15; 'awesome.': 0.16; 'imho,': 0.16; 'subject:copy': 0.16; 'wrote:': 0.16; 'wed,': 0.17; 'jan': 0.19; '(most': 0.21; 'cc:no real name:2**0': 0.21; 'feb': 0.22; 'header :In-Reply-To:1': 0.22; "shouldn't": 0.23; 'traceback': 0.24; 'cc:2**0': 0.25; 'pm,': 0.26; 'not.': 0.28; 'message- id:@mail.gmail.com': 0.28; 'cc:addr:python.org': 0.29; 'fri,': 0.30; 'typeerror:': 0.30; 'pretty': 0.30; 'does': 0.32; "can't": 0.32; 'object': 0.33; 'there': 0.33; 'normally': 0.34; 'assignment': 0.34; 'last):': 0.34; 'received:209.85.160.46': 0.35; 'received:mail-pw0-f46.google.com': 0.35; 'received:209.85.160': 0.35; 'file': 0.35; 'but': 0.37; 'received:google.com': 0.37; 'steven': 0.38; 'received:209.85': 0.38; 'think': 0.38; 'received:209': 0.39; 'subject:: ': 0.39; 'did': 0.39; 'john': 0.62; '-0800': 0.84; 'subject:write': 0.84; 'worthy': 0.84; 'conclude': 0.95
DKIM-Signature v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type:content-transfer-encoding; bh=4/rOxBcgt3A3sbzG/PefI4S77ZutNFBil+Rq73tVNtk=; b=mQI34Ryeleb3gh3qfVTyN9XTJHnrIjlCsUV51Upzr8FmNQbESAQLlLVacUXg2nThSy sbsWPoy1qsk7mAgGFR/0CVJgZO8SD7KVgf47pOTx6gQqrf44K5NE6lTM2/mfoz1gWWm0 auF6GwkqAf9xrdAUdLJWAetkKRXejoIk4uA/M=
MIME-Version 1.0
In-Reply-To <20120202141812.649c31d832bb15bd899eb952@johnohagan.com>
References <mailman.4709.1326455724.27778.python-list@python.org> <4f101f45$0$29999$c3e8da3$5496439d@news.astraweb.com> <mailman.4712.1326457859.27778.python-list@python.org> <4f102bd0$0$29999$c3e8da3$5496439d@news.astraweb.com> <4F107AAF.5000600@stoneleaf.us> <20120202141812.649c31d832bb15bd899eb952@johnohagan.com>
From Devin Jeanpierre <jeanpierreda@gmail.com>
Date Thu, 2 Feb 2012 01:34:48 -0500
Subject Re: copy on write
To "John O'Hagan" <research@johnohagan.com>
Content-Type text/plain; charset=UTF-8
Content-Transfer-Encoding quoted-printable
Cc python-list@python.org
X-BeenThere python-list@python.org
X-Mailman-Version 2.1.12
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.5343.1328164533.27778.python-list@python.org> (permalink)
Lines 26
NNTP-Posting-Host 2001:888:2000:d::a6
X-Trace 1328164533 news.xs4all.nl 6961 [2001:888:2000:d::a6]:57143
X-Complaints-To abuse@xs4all.nl
Xref x330-a1.tempe.blueboxinc.net comp.lang.python:19769

Show key headers only | View raw

On Wed, Feb 1, 2012 at 10:18 PM, John O'Hagan <research@johnohagan.com> wrote:
> On Fri, 13 Jan 2012 10:40:47 -0800
> Ethan Furman <ethan@stoneleaf.us> wrote:
>
>> Steven D'Aprano wrote:
>> > Normally this is harmless, but there is one interesting little
>> > glitch you can get:
>> >
>> >>>> t = ('a', [23])
>> >>>> t[1] += [42]
>> > Traceback (most recent call last):
>> >   File "<stdin>", line 1, in <module>
>> > TypeError: 'tuple' object does not support item assignment
>> >>>> t
>> > ('a', [23, 42])
>
> IMHO, this is worthy of bug-hood: shouldn't we be able to conclude from the TypeError that the assignment failed?

It did fail. The mutation did not.

I can't think of any way out of this misleadingness, although if you
can that would be pretty awesome.

-- Devin

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

Thread

copy on write Eduardo Suarez-Santana <esuarez@itccanarias.org> - 2012-01-13 11:33 +0000
  Re: copy on write Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-01-13 12:10 +0000
    Re: copy on write Chris Angelico <rosuav@gmail.com> - 2012-01-13 23:30 +1100
      Re: copy on write Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-01-13 13:04 +0000
        Re: copy on write Ethan Furman <ethan@stoneleaf.us> - 2012-01-13 10:40 -0800
          Re: copy on write 88888 Dihedral <dihedral88888@googlemail.com> - 2012-01-13 14:26 -0800
          Re: copy on write 88888 Dihedral <dihedral88888@googlemail.com> - 2012-01-13 14:26 -0800
        Re: copy on write John O'Hagan <research@johnohagan.com> - 2012-02-02 14:18 +1100
        Re: copy on write Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-02-02 01:34 -0500
        Re: copy on write John O'Hagan <research@johnohagan.com> - 2012-02-02 19:11 +1100
          Re: copy on write Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-02-02 09:16 +0000
            Re: copy on write Hrvoje Niksic <hniksic@xemacs.org> - 2012-02-02 11:53 +0100
              Re: copy on write MRAB <python@mrabarnett.plus.com> - 2012-02-02 16:28 +0000
              Re: copy on write Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-02-02 12:21 -0500
            Re: copy on write John O'Hagan <research@johnohagan.com> - 2012-02-03 01:17 +1100
            Re: copy on write Terry Reedy <tjreedy@udel.edu> - 2012-02-02 12:25 -0500
            Re: copy on write John O'Hagan <research@johnohagan.com> - 2012-02-03 14:08 +1100
              Re: copy on write Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-02-03 05:04 +0000
                Re: copy on write Chris Angelico <rosuav@gmail.com> - 2012-02-03 16:28 +1100
                Re: copy on write Rick Johnson <rantingrickjohnson@gmail.com> - 2012-02-03 07:35 -0800
                Re: copy on write Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2012-02-03 10:08 +0100
                Re: copy on write John O'Hagan <research@johnohagan.com> - 2012-02-03 21:47 +1100
                Re: copy on write Wolfram Hinderer <wolfram.hinderer@googlemail.com> - 2012-02-05 06:09 -0800
                Re: copy on write "OKB (not okblacke)" <brenNOSPAMbarn@NObrenSPAMbarn.net> - 2012-02-03 16:15 +0000
      Re: copy on write Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2012-02-02 11:42 +0100
    Re: copy on write Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-01-13 08:50 -0500
      Re: copy on write Grant Edwards <invalid@invalid.invalid> - 2012-01-13 15:13 +0000
        Re: copy on write Devin Jeanpierre <jeanpierreda@gmail.com> - 2012-01-13 11:48 -0500
          Re: copy on write Neil Cerutti <neilc@norwich.edu> - 2012-01-13 16:54 +0000
            Re: copy on write Grant Edwards <invalid@invalid.invalid> - 2012-01-13 18:15 +0000
              Re: copy on write Chris Angelico <rosuav@gmail.com> - 2012-01-14 05:26 +1100
                Re: copy on write Grant Edwards <invalid@invalid.invalid> - 2012-01-13 19:30 +0000
                Re: copy on write Neil Cerutti <neilc@norwich.edu> - 2012-01-13 20:11 +0000
            Re: copy on write Evan Driscoll <edriscoll@wisc.edu> - 2012-01-13 13:24 -0600
              Re: copy on write Neil Cerutti <neilc@norwich.edu> - 2012-01-13 21:20 +0000
                Re: copy on write Evan Driscoll <edriscoll@wisc.edu> - 2012-01-13 16:48 -0600
                Re: copy on write 88888 Dihedral <dihedral88888@googlemail.com> - 2012-02-02 05:33 -0800
                Re: copy on write Evan Driscoll <edriscoll@wisc.edu> - 2012-02-02 15:20 -0600
                Re: copy on write 88888 Dihedral <dihedral88888@googlemail.com> - 2012-02-02 05:33 -0800
                Re: copy on write 88888 Dihedral <dihedral88888@googlemail.com> - 2012-02-03 14:16 -0800
                Re: copy on write 88888 Dihedral <dihedral88888@googlemail.com> - 2012-02-03 14:16 -0800
          Re: copy on write Rick Johnson <rantingrickjohnson@gmail.com> - 2012-02-01 19:51 -0800
            Re: copy on write Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-02-02 05:31 +0000

csiph-web