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

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	2013-06-22 23:40 -0600
Subject	Re: What is the semantics meaning of 'object'?
Newsgroups	comp.lang.python
Message-ID	<mailman.3725.1371967812.3114.python-list@python.org> (permalink)

Show all headers | 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.

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