Re: can't add variables to instances of built-in classes

From	Ethan Furman <ethan@stoneleaf.us>
Newsgroups	comp.lang.python
Subject	Re: can't add variables to instances of built-in classes
Date	2016-07-18 06:10 -0700
Message-ID	<mailman.74.1468847389.2307.python-list@python.org> (permalink)
References	<4f796d95-0e87-4610-a0a8-1eff07c60ace@googlegroups.com> <nmfqrg$ea7$1@ger.gmane.org> <mailman.63.1468755660.2307.python-list@python.org> <b24bede0-be29-4c45-856e-90e6a63c99d0@googlegroups.com> <578CD530.5090702@stoneleaf.us>

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On 07/17/2016 04:50 AM, Wilson Ong wrote:

>> Use this feature sparingly, only when you know that there are going to be
>> many (millions rather than thousands) of Test instances.
>
> Why use it sparingly? Is it for extensibility? What if I'm pretty sure that
>  my class is going to have exactly these attributes only?

One of the very nice things about Python is being able to fiddle with objects, both
for debugging and for extending.  One of the ways that's accomplished is by adding
attributes to instances, but when __slots__ is defined that ability is lost, which
can make using/debugging those types of objects harder.

__slots__ is a memory optimization, and like most optimazations you shouldn't use
it until you know you need it.

--
~Ethan~

Thread

can't add variables to instances of built-in classes Kent Tong <kent.tong.mo@gmail.com> - 2016-07-17 03:57 -0700
  Re: can't add variables to instances of built-in classes Peter Otten <__peter__@web.de> - 2016-07-17 13:40 +0200
    Re: can't add variables to instances of built-in classes Wilson Ong <wilsonokw@gmail.com> - 2016-07-17 04:50 -0700
      Re: can't add variables to instances of built-in classes Chris Angelico <rosuav@gmail.com> - 2016-07-17 22:02 +1000
      Re: can't add variables to instances of built-in classes Steven D'Aprano <steve@pearwood.info> - 2016-07-18 01:04 +1000
        Re: can't add variables to instances of built-in classes Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-17 20:00 -0700
          Re: can't add variables to instances of built-in classes Peter Otten <__peter__@web.de> - 2016-07-18 09:38 +0200
            Re: can't add variables to instances of built-in classes Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-18 14:48 -0700
              Re: can't add variables to instances of built-in classes breamoreboy@gmail.com - 2016-07-18 16:12 -0700
                Re: can't add variables to instances of built-in classes Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-18 19:53 -0700
                Re: can't add variables to instances of built-in classes breamoreboy@gmail.com - 2016-07-19 14:24 -0700
                Re: can't add variables to instances of built-in classes Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-19 16:58 -0700
                Re: can't add variables to instances of built-in classes Chris Angelico <rosuav@gmail.com> - 2016-07-20 16:19 +1000
                Re: can't add variables to instances of built-in classes Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-19 23:45 -0700
                Re: can't add variables to instances of built-in classes Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-07-20 17:22 +1000
                Re: can't add variables to instances of built-in classes Peter Otten <__peter__@web.de> - 2016-07-20 09:26 +0200
                Re: can't add variables to instances of built-in classes Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-20 01:50 -0700
                Re: can't add variables to instances of built-in classes Peter Otten <__peter__@web.de> - 2016-07-20 11:15 +0200
                Re: can't add variables to instances of built-in classes Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-20 15:11 -0700
                Re: can't add variables to instances of built-in classes Chris Angelico <rosuav@gmail.com> - 2016-07-21 12:29 +1000
                Re: can't add variables to instances of built-in classes Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-08-03 19:34 -0700
                Re: can't add variables to instances of built-in classes Chris Angelico <rosuav@gmail.com> - 2016-08-04 13:00 +1000
                Re: can't add variables to instances of built-in classes Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-08-04 16:57 -0700
                Re: can't add variables to instances of built-in classes Steven D'Aprano <steve@pearwood.info> - 2016-07-21 12:48 +1000
                Re: can't add variables to instances of built-in classes Steven D'Aprano <steve@pearwood.info> - 2016-07-20 22:10 +1000
                Re: can't add variables to instances of built-in classes Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-20 14:48 -0700
                Re: can't add variables to instances of built-in classes breamoreboy@gmail.com - 2016-07-20 18:04 -0700
                Re: can't add variables to instances of built-in classes Peter Otten <__peter__@web.de> - 2016-07-21 08:59 +0200
              Re: can't add variables to instances of built-in classes Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-07-20 02:10 -0700
      Re: can't add variables to instances of built-in classes Ethan Furman <ethan@stoneleaf.us> - 2016-07-18 06:10 -0700
  Re: can't add variables to instances of built-in classes Kent Tong <kent.tong.mo@gmail.com> - 2016-07-17 04:53 -0700

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