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Re: An object is an instance (or not)?

From Gregory Ewing <greg.ewing@canterbury.ac.nz>
Newsgroups comp.lang.python
Subject Re: An object is an instance (or not)?
Date 2015-01-28 20:21 +1300
Message-ID <cirgvaFtgueU1@mid.individual.net> (permalink)
References <MPG.2f320f923eedd5a69896a1@nntp.aioe.org> <80a9f882-6b13-45a7-b514-8c47b3a4c37d@googlegroups.com> <MPG.2f321c24a502d2bb9896a3@nntp.aioe.org>

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Mario Figueiredo wrote:
> That error message has me start that thread arguing that the error is 
> misleading because the Sub object does have the __bases__ attribute. 
> It's the Sub instance object that does not have it.
> 
> Some of the answers that were given argued that in Python object = 
> instance.

No, they pointed out that *in that particular sentence* the
word "object" was being used in a way that's more or less
synonymous with "instance".

But that doesn't mean the two words are perfectly
interchangeable in all English sentences. Sometimes one
is better than the other.

I prefer to use the word "instance" when I'm talking about
an instance *of* something, e.g. "an instance of Foo" or
"a Foo instance". If I'm not mentioning a class, I just
use the word "object".

So I would argue that "Sub instance has no attribute..."
is a marginally clearer way to word that message.

Which means, I think, that I'm more or less agreeing with
you, but *not* because of objects not always being instances
in Python. On the contrary, it's precisely because all
objects *are* instances that using the word "instance"
on its own in place of "object" is pointless -- it
doesn't convey any extra information.

-- 
Greg

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Thread

An object is an instance (or not)? Mario Figueiredo <marfig@gmail.com> - 2015-01-27 21:12 +0100
  Re: An object is an instance (or not)? Ethan Furman <ethan@stoneleaf.us> - 2015-01-27 12:36 -0800
  Re: An object is an instance (or not)? André Roberge <andre.roberge@gmail.com> - 2015-01-27 12:50 -0800
    Re: An object is an instance (or not)? Mario Figueiredo <marfig@gmail.com> - 2015-01-27 22:06 +0100
      Re: An object is an instance (or not)? André Roberge <andre.roberge@gmail.com> - 2015-01-27 13:38 -0800
        Re: An object is an instance (or not)? Mario Figueiredo <marfig@gmail.com> - 2015-01-27 22:43 +0100
          Re: An object is an instance (or not)? André Roberge <andre.roberge@gmail.com> - 2015-01-27 13:49 -0800
            Re: An object is an instance (or not)? Mario Figueiredo <marfig@gmail.com> - 2015-01-27 22:58 +0100
              Re: An object is an instance (or not)? Ben Finney <ben+python@benfinney.id.au> - 2015-01-28 09:32 +1100
                Re: An object is an instance (or not)? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-28 18:55 +1100
                Re: An object is an instance (or not)? Ben Finney <ben+python@benfinney.id.au> - 2015-01-28 22:20 +1100
              Re: An object is an instance (or not)? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-01-27 23:12 +0000
                Re: An object is an instance (or not)? Mario Figueiredo <marfig@gmail.com> - 2015-01-28 01:52 +0100
                Re: An object is an instance (or not)? Marko Rauhamaa <marko@pacujo.net> - 2015-01-28 07:25 +0200
                Re: An object is an instance (or not)? Rustom Mody <rustompmody@gmail.com> - 2015-01-27 21:53 -0800
                Re: An object is an instance (or not)? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-01-28 05:57 +0000
                Re: An object is an instance (or not)? Mario Figueiredo <marfig@gmail.com> - 2015-01-28 11:48 +0100
      Re: An object is an instance (or not)? random832@fastmail.us - 2015-01-28 00:37 -0500
        Re: An object is an instance (or not)? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-28 19:45 +1100
      Re: An object is an instance (or not)? Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-01-27 21:43 -0800
      Re: An object is an instance (or not)? random832@fastmail.us - 2015-01-28 01:01 -0500
        Re: An object is an instance (or not)? Rustom Mody <rustompmody@gmail.com> - 2015-01-27 22:22 -0800
          Re: An object is an instance (or not)? Ben Finney <ben+python@benfinney.id.au> - 2015-01-28 18:03 +1100
        Re: An object is an instance (or not)? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-28 19:48 +1100
      Re: An object is an instance (or not)? Ben Finney <ben+python@benfinney.id.au> - 2015-01-28 17:59 +1100
      Re: An object is an instance (or not)? Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-01-28 20:21 +1300
      Re: An object is an instance (or not)? Ben Finney <ben+python@benfinney.id.au> - 2015-01-28 18:48 +1100
      Re: An object is an instance (or not)? random832@fastmail.us - 2015-01-28 12:08 -0500
        Re: An object is an instance (or not)? Rustom Mody <rustompmody@gmail.com> - 2015-01-28 18:29 -0800
  Re: An object is an instance (or not)? Ned Batchelder <ned@nedbatchelder.com> - 2015-01-27 18:22 -0500
    Re: An object is an instance (or not)? Mario Figueiredo <marfig@gmail.com> - 2015-01-28 01:17 +0100
      Re: An object is an instance (or not)? Chris Angelico <rosuav@gmail.com> - 2015-01-28 11:30 +1100
        Re: An object is an instance (or not)? Mario Figueiredo <marfig@gmail.com> - 2015-01-28 01:35 +0100
          Re: An object is an instance (or not)? alex23 <wuwei23@gmail.com> - 2015-01-28 14:44 +1000
          Re: An object is an instance (or not)? Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-01-28 23:33 +1300
            Re: An object is an instance (or not)? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-28 22:52 +1100
              Re: An object is an instance (or not)? Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-01-29 19:22 +1300
                Re: An object is an instance (or not)? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-29 18:16 +1100
                Re: An object is an instance (or not)? Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-29 08:48 -0700
                Re: An object is an instance (or not)? Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-01-30 22:07 +1300
                Re: An object is an instance (or not)? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-31 10:45 +1100
      Re: An object is an instance (or not)? Ned Batchelder <ned@nedbatchelder.com> - 2015-01-27 21:21 -0500
        Re: An object is an instance (or not)? Rustom Mody <rustompmody@gmail.com> - 2015-01-27 18:52 -0800
        Re: An object is an instance (or not)? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-28 20:16 +1100
          Re: An object is an instance (or not)? Chris Angelico <rosuav@gmail.com> - 2015-01-28 21:01 +1100
            Re: An object is an instance (or not)? Rick Johnson <rantingrickjohnson@gmail.com> - 2015-01-29 14:22 -0800
      Re: An object is an instance (or not)? Ian Kelly <ian.g.kelly@gmail.com> - 2015-01-27 19:15 -0700
      Re: An object is an instance (or not)? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-28 20:28 +1100
      Re: An object is an instance (or not)? Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-01-28 23:33 +1300
    Re: An object is an instance (or not)? Grant Edwards <invalid@invalid.invalid> - 2015-01-28 00:23 +0000
  Re: An object is an instance (or not)? Ben Finney <ben+python@benfinney.id.au> - 2015-01-28 10:39 +1100
    Re: An object is an instance (or not)? Mario Figueiredo <marfig@gmail.com> - 2015-01-28 01:24 +0100
      Re: An object is an instance (or not)? Ben Finney <ben+python@benfinney.id.au> - 2015-01-28 12:00 +1100
        Re: An object is an instance (or not)? Mario Figueiredo <marfig@gmail.com> - 2015-01-28 02:14 +0100
      Re: An object is an instance (or not)? alex23 <wuwei23@gmail.com> - 2015-01-28 14:47 +1000
        Re: An object is an instance (or not)? Rustom Mody <rustompmody@gmail.com> - 2015-01-27 21:23 -0800
        Re: An object is an instance (or not)? random832@fastmail.us - 2015-01-28 00:44 -0500
          Re: An object is an instance (or not)? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-28 20:21 +1100
      Re: An object is an instance (or not)? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-28 20:17 +1100
    Re: An object is an instance (or not)? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-01-28 20:09 +1100
  Re: An object is an instance (or not)? Chris Angelico <rosuav@gmail.com> - 2015-01-28 10:42 +1100
    Re: An object is an instance (or not)? Mario Figueiredo <marfig@gmail.com> - 2015-01-28 01:31 +0100
  Re: An object is an instance (or not)? Rustom Mody <rustompmody@gmail.com> - 2015-01-27 18:11 -0800

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