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

Groups > comp.lang.python > #48978

Re: What is the semantics meaning of 'object'?

Path csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!news.albasani.net!newsfeed.fsmpi.rwth-aachen.de!news.unit0.net!news2.euro.net!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path <ian.g.kelly@gmail.com>
X-Original-To python-list@python.org
Delivered-To python-list@mail.python.org
X-Spam-Status OK 0.013
X-Spam-Evidence '*H*': 0.97; '*S*': 0.00; '(even': 0.05; 'differently': 0.07; 'method.': 0.07; 'suppose': 0.07; '22,': 0.09; 'methods,': 0.09; 'override': 0.09; 'python': 0.11; '__del__': 0.16; 'behave': 0.16; 'exceptions,': 0.16; 'garbage': 0.16; 'inconvenient': 0.16; 'magic': 0.16; 'new-style': 0.16; 'overridden': 0.16; 'overriding': 0.16; 'proxy,': 0.16; 'side.': 0.16; 'subject:object': 0.16; 'sat,': 0.16; ':-)': 0.16; 'do,': 0.16; 'wrote:': 0.18; 'proxy': 0.24; 'simpler': 0.24; 'regardless': 0.24; 'header:In-Reply-To:1': 0.27; 'generally': 0.29; "doesn't": 0.30; 'message-id:@mail.gmail.com': 0.30; "i'm": 0.30; 'about.': 0.31; "d'aprano": 0.31; 'steven': 0.31; 'probably': 0.32; 'implemented': 0.33; 'not.': 0.33; 'skip:_ 10': 0.34; 'subject:the': 0.34; 'could': 0.34; "can't": 0.35; 'classes': 0.35; 'something': 0.35; '(2)': 0.35; 'objects': 0.35; 'but': 0.35; 'received:google.com': 0.35; 'there': 0.35; 'really': 0.36; 'curious': 0.36; 'doing': 0.36; 'method': 0.36; 'should': 0.36; 'wrong': 0.37; 'two': 0.37; 'implement': 0.38; 'somebody': 0.38; 'to:addr:python-list': 0.38; 'pm,': 0.38; 'does': 0.39; 'bad': 0.39; 'sure': 0.39; 'to:addr:python.org': 0.39; 'ian': 0.60; 'manually': 0.60; 'skip:* 10': 0.61; "you're": 0.61; 'first': 0.61; 'such': 0.63; 'provide': 0.64; 'more': 0.64; 'due': 0.66; 'delegate': 0.68; 'default': 0.69; 'calls,': 0.84; 'delegated': 0.84; 'hardly': 0.84; 'regard.': 0.84; 'troublesome': 0.91; '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:from:date:message-id:subject:to :content-type; bh=asSm6z8rFzUhsYhJSr39qlIijllBCXXL0qiOsSCpScs=; b=YAVwaIEyq+XCFf6Lvi6+0leYzfOQrA6+odIyZSh5oVM6vRVx/lxeJJtxThyCUnXWg3 k9IDEuKPvVMIHAC2+otHSwZZAVPccauuKdC1f211mXDOCZzCMRbnDWAWYXe/LQcruRfR plPDLGdrzwM9zGbRq0wb+PaT27x3WBTsFKpr6MmBg44HcurgKnGMy74Z/HnE1nrAuVE9 LGQlj46Tmq14RuAdmmY4PF4cPl6972YIqEcG4yHyPMcZJfBOJGJ9NnFs3zNBhWy1JyMH 4kAPAvSxZs3qi6IwIEgV1wD0jZeiVjXd0+2lE8gkx0dCxHYrlxNg5L6DHBaYbcuh1kHu GjQg==
X-Received by 10.66.146.9 with SMTP id sy9mr23051917pab.16.1371966093727; Sat, 22 Jun 2013 22:41:33 -0700 (PDT)
MIME-Version 1.0
In-Reply-To <51c68638$0$29999$c3e8da3$5496439d@news.astraweb.com>
References <15ba0011-bbf1-42f7-b3ea-1c1d4b70e56b@googlegroups.com> <51c66962$0$29999$c3e8da3$5496439d@news.astraweb.com> <mailman.3724.1371961680.3114.python-list@python.org> <51c68638$0$29999$c3e8da3$5496439d@news.astraweb.com>
From Ian Kelly <ian.g.kelly@gmail.com>
Date Sat, 22 Jun 2013 23:40:53 -0600
Subject Re: What is the semantics meaning of 'object'?
To Python <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 <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.3725.1371967812.3114.python-list@python.org> (permalink)
Lines 46
NNTP-Posting-Host 2001:888:2000:d::a6
X-Trace 1371967812 news.xs4all.nl 15975 [2001:888:2000:d::a6]:34291
X-Complaints-To abuse@xs4all.nl
Xref csiph.com comp.lang.python:48978

Show key headers only | View raw

On Sat, Jun 22, 2013 at 11:23 PM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> On Sat, 22 Jun 2013 22:27:10 -0600, Ian Kelly wrote:
>> I actually consider that an up side.  Sure it's inconvenient that you
>> can't delegate all such methods at once just by overriding
>> __getattribute__, but it would be more troublesome to *accidentally*
>> implement such methods because you implemented __getattribute__.
>
> It's hard to see a case where that would be a bad thing.
>
> 1) If the proxied object doesn't include __dunder__ methods, then the
> proxy will just end up up calling the default object dunder methods,
> exactly as if they weren't proxied.
>
> 2) If the proxied object does include dunders, then you generally want
> the proxy to call them, with perhaps one or two exceptions, which need to
> be overridden regardless of whether they are dunders or not.

Proxying objects is not the only use of __getattribute__.

>> And
>> then there are methods that really should not be delegated in the first
>> place, like __del__.
>
> If you're using __del__, you're probably doing something wrong :-)
>
> I suppose that __del__ is a good counter-example, but (1) hardly any
> classes use __del__, and (2) for those that do, it's *way* simpler to
> manually override __del__ in the proxy than to manually delegate every
> dunder method you care about. There are typically a lot of dunder methods
> you care about.

If you manually override __del__ in the proxy, then as far as the
garbage collector is concerned, your proxy object has a __del__ method
(even if it does nothing), and so it will be treated differently from
an object without a __del__ method.

> It is not the case that dunder methods cannot be automatically proxied
> because somebody deliberately designed Python to work that way. It's an
> accidental side-effect of the way new-style classes resolve method calls,
> due to decisions made for other reasons having nothing to do with
> delegation.

Can you elaborate or provide a link?  I'm curious to know what other
reason there could be for magic methods to behave differently from
normal methods in this regard.

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

Thread

What is the semantics meaning of 'object'? Adam <jiang.adam@gmail.com> - 2013-06-22 19:58 -0700
  Re: What is the semantics meaning of 'object'? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-23 03:20 +0000
    Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-22 22:27 -0600
      Re: What is the semantics meaning of 'object'? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-23 05:23 +0000
        Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-22 23:40 -0600
          Re: What is the semantics meaning of 'object'? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-23 17:29 +0000
            Re: What is the semantics meaning of 'object'? Rotwang <sg552@hotmail.co.uk> - 2013-06-24 02:53 +0100
              Re: What is the semantics meaning of 'object'? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-24 06:31 +0000
                Re: What is the semantics meaning of 'object'? Rotwang <sg552@hotmail.co.uk> - 2013-06-24 16:00 +0100
                Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-24 11:23 -0600
    Re: What is the semantics meaning of 'object'? Adam Jiang <jiang.adam@gmail.com> - 2013-06-23 22:35 +0900
    Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-23 10:15 -0600
      Re: What is the semantics meaning of 'object'? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-23 16:35 +0000
        Re: What is the semantics meaning of 'object'? Roy Smith <roy@panix.com> - 2013-06-23 12:49 -0400
          Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-23 11:08 -0600
            Re: What is the semantics meaning of 'object'? Roy Smith <roy@panix.com> - 2013-06-23 14:14 -0400
          Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-23 11:18 -0600
            Re: What is the semantics meaning of 'object'? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-23 17:36 +0000
              Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-23 12:04 -0600
                Re: What is the semantics meaning of 'object'? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-23 18:50 +0000
                Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-23 13:09 -0600
                Re: What is the semantics meaning of 'object'? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-24 01:12 +0000
                Re: What is the semantics meaning of 'object'? Roy Smith <roy@panix.com> - 2013-06-23 15:24 -0400
                Re: What is the semantics meaning of 'object'? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-24 01:27 +0000
                Re: What is the semantics meaning of 'object'? Roy Smith <roy@panix.com> - 2013-06-23 21:38 -0400
                Re: What is the semantics meaning of 'object'? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-24 08:06 +0000
                Re: What is the semantics meaning of 'object'? Roy Smith <roy@panix.com> - 2013-06-24 08:41 -0400
                Re: What is the semantics meaning of 'object'? Mark Janssen <dreamingforward@gmail.com> - 2013-06-24 08:58 -0700
                Re: What is the semantics meaning of 'object'? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-24 23:51 +0000
                Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-24 11:26 -0600
                Re: What is the semantics meaning of 'object'? Ethan Furman <ethan@stoneleaf.us> - 2013-06-26 13:14 -0700
                Re: What is the semantics meaning of 'object'? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-26 23:54 +0000
                Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-26 19:03 -0600
                Re: What is the semantics meaning of 'object'? Ethan Furman <ethan@stoneleaf.us> - 2013-06-26 17:38 -0700
          Re: What is the semantics meaning of 'object'? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-23 18:46 +0000
            Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-23 13:05 -0600
            Re: What is the semantics meaning of 'object'? Ethan Furman <ethan@stoneleaf.us> - 2013-06-26 13:37 -0700
          Re: What is the semantics meaning of 'object'? Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-23 13:33 -0700
        Re: What is the semantics meaning of 'object'? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-23 21:33 +0200
        Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-25 11:44 -0600
        Re: What is the semantics meaning of 'object'? Mark Janssen <dreamingforward@gmail.com> - 2013-06-25 14:58 -0700
        Re: What is the semantics meaning of 'object'? Chris Angelico <rosuav@gmail.com> - 2013-06-26 08:17 +1000
        Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-25 16:21 -0600
        Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-25 16:25 -0600
        Re: What is the semantics meaning of 'object'? Mark Janssen <dreamingforward@gmail.com> - 2013-06-25 15:29 -0700
        Re: What is the semantics meaning of 'object'? Mark Janssen <dreamingforward@gmail.com> - 2013-06-25 15:27 -0700
        Re: What is the semantics meaning of 'object'? Mark Janssen <dreamingforward@gmail.com> - 2013-06-25 15:38 -0700
        Re: What is the semantics meaning of 'object'? Chris Angelico <rosuav@gmail.com> - 2013-06-26 08:39 +1000
        Re: What is the semantics meaning of 'object'? Chris Angelico <rosuav@gmail.com> - 2013-06-26 08:47 +1000
        Re: What is the semantics meaning of 'object'? Chris Angelico <rosuav@gmail.com> - 2013-06-26 08:57 +1000
          Re: What is the semantics meaning of 'object'? Rotwang <sg552@hotmail.co.uk> - 2013-06-26 16:16 +0100
            Re: What is the semantics meaning of 'object'? Chris Angelico <rosuav@gmail.com> - 2013-06-27 01:23 +1000
        Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-25 17:07 -0600
        Re: What is the semantics meaning of 'object'? Chris Angelico <rosuav@gmail.com> - 2013-06-26 09:08 +1000
        Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-25 17:10 -0600
        Re: What is the semantics meaning of 'object'? Mark Janssen <dreamingforward@gmail.com> - 2013-06-25 16:19 -0700
          Re: What is the semantics meaning of 'object'? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-26 08:36 +0000
          Re: What is the semantics meaning of 'object'? alex23 <wuwei23@gmail.com> - 2013-06-28 10:19 +1000
            Re: What is the semantics meaning of 'object'? Mark Janssen <dreamingforward@gmail.com> - 2013-06-28 11:55 -0700
        Re: What is the semantics meaning of 'object'? Mark Janssen <dreamingforward@gmail.com> - 2013-06-25 16:00 -0700
        Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-25 18:19 -0600
        Re: What is the semantics meaning of 'object'? Mark Janssen <dreamingforward@gmail.com> - 2013-06-25 18:07 -0700
        Re: What is the semantics meaning of 'object'? Chris Angelico <rosuav@gmail.com> - 2013-06-26 17:25 +1000
        Re: What is the semantics meaning of 'object'? Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-26 02:53 -0600
        Re: What is the semantics meaning of 'object'? Chris Angelico <rosuav@gmail.com> - 2013-06-26 09:54 +1000
        Re: What is the semantics meaning of 'object'? Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-26 12:56 +0200
      Re: What is the semantics meaning of 'object'? Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-23 13:12 -0700

csiph-web