Re: Everything is an object in python - object class and type class

From	Marko Rauhamaa <marko@pacujo.net>
Newsgroups	comp.lang.python
Subject	Re: Everything is an object in python - object class and type class
Date	2015-06-02 12:23 +0300
Organization	A noiseless patient Spider
Message-ID	<87zj4i79b5.fsf@elektro.pacujo.net> (permalink)
References	(1 earlier) <7f287dcf-8d52-4ab8-9768-88d1f75da269@googlegroups.com> <bb48ac94-c2ac-4874-9c95-7ac2280fd5bc@googlegroups.com> <556d574f$0$12905$c3e8da3$5496439d@news.astraweb.com> <3d06de71-a517-4cac-be12-a61813465735@googlegroups.com> <mailman.48.1433234251.13271.python-list@python.org>

Show all headers | View raw

Chris Angelico <rosuav@gmail.com>:

> On Tue, Jun 2, 2015 at 5:44 PM, Rustom Mody <rustompmody@gmail.com> wrote:
>> 1 ∈ all these
>> Are the '∈'s here same?  Similar?
>
> Yes, they are. Every one of them is asserting (or asking, depending on
> your point of view) whether or not the instance to its left is a
> member of the set to its right. The sets on the right are all
> different, but the set membership operation is identical.

That is the risk of taking classes into Python. People start to obsess
about membership and ontological relationships. I think you should use
the type() function only for troubleshooting and isinstance() virtually
never.

I think objects should be understood only through their operational
semantics, ie, their methods. It doesn't matter what an object is; what
matters is what it does. Don't test it, just call it.

Yeah, I'm preaching to the choir:

   Alex Martelli made an early (2000) use of the term in a message to
   the comp.lang.python newsgroup:

       In other words, don't check whether it IS-a duck: check whether
       it QUACKS-like-a duck, WALKS-like-a duck, etc, etc, depending on
       exactly what subset of duck-like behaviour you need to play your
       language-games with.

   <URL: http://en.wikipedia.org/wiki/Duck_typing>

Marko

PS I have written code that violates my stated rule. For example, an
argument could be a string or a list of strings for convenience.
However, this kind of testing should not be performed on anything
created with the "class" keyword. IOW, some types *are* more primitive
than others -- in our minds and in practical use.

Thread

Everything is an object in python - object class and type class Eddilbert Macharia <edd.cowan@gmail.com> - 2015-05-31 07:34 -0700
  Re: Everything is an object in python - object class and type class Marco Buttu <marco.buttu@gmail.com> - 2015-05-31 17:13 +0200
  Re: Everything is an object in python - object class and type class Terry Reedy <tjreedy@udel.edu> - 2015-05-31 11:37 -0400
  Re: Everything is an object in python - object class and type class Steven D'Aprano <steve@pearwood.info> - 2015-06-01 04:00 +1000
    Re: Everything is an object in python - object class and type class "Dr. Bigcock" <dreamingforward@gmail.com> - 2015-06-01 10:35 -0700
  Re: Everything is an object in python - object class and type class Eddilbert Macharia <edd.cowan@gmail.com> - 2015-05-31 17:29 -0700
    Re: Everything is an object in python - object class and type class Steven D'Aprano <steve@pearwood.info> - 2015-06-01 14:09 +1000
  Re: Everything is an object in python - object class and type class Eddilbert Macharia <edd.cowan@gmail.com> - 2015-05-31 20:09 -0700
    Re: Everything is an object in python - object class and type class Steven D'Aprano <steve@pearwood.info> - 2015-06-01 14:24 +1000
  Re: Everything is an object in python - object class and type class Eddilbert Macharia <edd.cowan@gmail.com> - 2015-06-01 05:03 -0700
    Re: Everything is an object in python - object class and type class BartC <bc@freeuk.com> - 2015-06-01 23:59 +0100
      Re: Everything is an object in python - object class and type class BartC <bc@freeuk.com> - 2015-06-02 11:45 +0100
        Re: Everything is an object in python - object class and type class Rustom Mody <rustompmody@gmail.com> - 2015-06-02 04:16 -0700
      Re: Everything is an object in python - object class and type class Ian Kelly <ian.g.kelly@gmail.com> - 2015-06-02 09:09 -0600
    Re: Everything is an object in python - object class and type class TheDoctor <dreamingforward@gmail.com> - 2015-06-01 17:24 -0700
      Re: Everything is an object in python - object class and type class Chris Angelico <rosuav@gmail.com> - 2015-06-02 10:32 +1000
        Re: Everything is an object in python - object class and type class TheDoctor <dreamingforward@gmail.com> - 2015-06-01 18:02 -0700
          Re: Everything is an object in python - object class and type class Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-06-02 16:30 +1000
        Re: Everything is an object in python - object class and type class TheDoctor <dreamingforward@gmail.com> - 2015-06-01 18:15 -0700
          Re: Everything is an object in python - object class and type class Chris Angelico <rosuav@gmail.com> - 2015-06-02 11:30 +1000
          Re: Everything is an object in python - object class and type class random832@fastmail.us - 2015-06-02 00:13 -0400
          Re: Everything is an object in python - object class and type class Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-06-02 16:23 +1000
      Re: Everything is an object in python - object class and type class Rustom Mody <rustompmody@gmail.com> - 2015-06-01 20:15 -0700
        Re: Everything is an object in python - object class and type class Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-02 04:46 +0100
        Re: Everything is an object in python - object class and type class TheDoctor <dreamingforward@gmail.com> - 2015-06-01 21:47 -0700
          Re: Everything is an object in python - object class and type class Rustom Mody <rustompmody@gmail.com> - 2015-06-01 22:01 -0700
            Religion [was Re: Everything is an object in python - object class and type class] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-06-02 16:04 +1000
              Re: Religion [was Re: Everything is an object in python - object class and type class] Rustom Mody <rustompmody@gmail.com> - 2015-06-01 23:17 -0700
              Re: Religion [was Re: Everything is an object in python - object class and type class] Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-02 07:20 +0100
      Re: Everything is an object in python - object class and type class random832@fastmail.us - 2015-06-02 00:08 -0400
        Re: Everything is an object in python - object class and type class TheDoctor <dreamingforward@gmail.com> - 2015-06-01 21:54 -0700
      Re: Everything is an object in python - object class and type class Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-06-02 17:12 +1000
        Re: Everything is an object in python - object class and type class Rustom Mody <rustompmody@gmail.com> - 2015-06-02 00:44 -0700
          Re: Everything is an object in python - object class and type class Chris Angelico <rosuav@gmail.com> - 2015-06-02 18:37 +1000
            Re: Everything is an object in python - object class and type class Rustom Mody <rustompmody@gmail.com> - 2015-06-02 02:18 -0700
            Re: Everything is an object in python - object class and type class Marko Rauhamaa <marko@pacujo.net> - 2015-06-02 12:23 +0300
  Re: Everything is an object in python - object class and type class vern.muhr@gmail.com - 2015-06-01 14:12 -0700
  Re: Everything is an object in python - object class and type class Eddilbert Macharia <edd.cowan@gmail.com> - 2015-06-02 03:36 -0700
    Re: Everything is an object in python - object class and type class Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-02 12:11 +0100
    Re: Everything is an object in python - object class and type class Steven D'Aprano <steve@pearwood.info> - 2015-06-02 21:27 +1000
      Re: Everything is an object in python - object class and type class Rustom Mody <rustompmody@gmail.com> - 2015-06-02 04:40 -0700
        Re: Everything is an object in python - object class and type class Steven D'Aprano <steve@pearwood.info> - 2015-06-03 01:08 +1000
          Re: Everything is an object in python - object class and type class Rustom Mody <rustompmody@gmail.com> - 2015-06-02 09:14 -0700
      Re: Everything is an object in python - object class and type class BartC <bc@freeuk.com> - 2015-06-02 13:49 +0100
        Re: Everything is an object in python - object class and type class Marko Rauhamaa <marko@pacujo.net> - 2015-06-02 16:13 +0300
        Re: Everything is an object in python - object class and type class Steven D'Aprano <steve@pearwood.info> - 2015-06-03 03:00 +1000
          Re: Everything is an object in python - object class and type class BartC <bc@freeuk.com> - 2015-06-02 18:59 +0100
            Re: Everything is an object in python - object class and type class random832@fastmail.us - 2015-06-02 14:07 -0400
            Re: Everything is an object in python - object class and type class Ned Batchelder <ned@nedbatchelder.com> - 2015-06-02 11:10 -0700
              Re: Everything is an object in python - object class and type class Ian Kelly <ian.g.kelly@gmail.com> - 2015-06-02 13:36 -0600
            Re: Everything is an object in python - object class and type class Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-02 18:10 +0000
            Re: Everything is an object in python - object class and type class "Dr. Bigcock" <dreamingforward@gmail.com> - 2015-06-02 11:22 -0700
              Re: Everything is an object in python - object class and type class Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-02 18:47 +0000
                Re: Everything is an object in python - object class and type class "Dr. Bigcock" <dreamingforward@gmail.com> - 2015-06-02 12:00 -0700
                Re: Everything is an object in python - object class and type class Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-06-02 19:31 +0000
                Re: Everything is an object in python - object class and type class Ian Kelly <ian.g.kelly@gmail.com> - 2015-06-02 13:50 -0600
                Re: Everything is an object in python - object class and type class Grant Edwards <invalid@invalid.invalid> - 2015-06-02 21:19 +0000
                Re: Everything is an object in python - object class and type class Marko Rauhamaa <marko@pacujo.net> - 2015-06-03 01:33 +0300
                Re: Everything is an object in python - object class and type class "Dr. Bigcock" <dreamingforward@gmail.com> - 2015-06-02 15:49 -0700
                Re: Everything is an object in python - object class and type class Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-06-03 18:13 +1000
                Re: Everything is an object in python - object class and type class "Dr. Bigcock" <dreamingforward@gmail.com> - 2015-06-03 21:38 -0700
                Re: Everything is an object in python - object class and type class Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-06-03 18:24 +1000
                Re: Everything is an object in python - object class and type class Marko Rauhamaa <marko@pacujo.net> - 2015-06-03 11:57 +0300
                Re: Everything is an object in python - object class and type class Ian Kelly <ian.g.kelly@gmail.com> - 2015-06-03 07:57 -0600
                Re: Everything is an object in python - object class and type class "Dr. Bigcock" <dreamingforward@gmail.com> - 2015-06-03 21:42 -0700
                Re: Everything is an object in python - object class and type class "Dr. Bigcock" <dreamingforward@gmail.com> - 2015-06-02 12:58 -0700
                Re: Everything is an object in python - object class and type class Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-02 22:47 +0100
                Re: Everything is an object in python - object class and type class Ian Kelly <ian.g.kelly@gmail.com> - 2015-06-02 18:49 -0600
                Re: Everything is an object in python - object class and type class Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-06-03 18:32 +1000
                Re: Everything is an object in python - object class and type class Ian Kelly <ian.g.kelly@gmail.com> - 2015-06-02 13:37 -0600
            Re: Everything is an object in python - object class and type class Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-06-03 18:08 +1000
          Re: Everything is an object in python - object class and type class "Dr. Bigcock" <dreamingforward@gmail.com> - 2015-06-02 11:00 -0700
      Re: Everything is an object in python - object class and type class Eddilbert Macharia <edd.cowan@gmail.com> - 2015-06-02 21:16 -0700
        Re: Everything is an object in python - object class and type class Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-03 06:23 +0100
        Re: Everything is an object in python - object class and type class BartC <bc@freeuk.com> - 2015-06-03 11:20 +0100
          Re: Everything is an object in python - object class and type class Chris Angelico <rosuav@gmail.com> - 2015-06-03 20:38 +1000
            Re: Everything is an object in python - object class and type class BartC <bc@freeuk.com> - 2015-06-03 12:08 +0100
              Re: Everything is an object in python - object class and type class Marko Rauhamaa <marko@pacujo.net> - 2015-06-03 15:08 +0300
                Re: Everything is an object in python - object class and type class BartC <bc@freeuk.com> - 2015-06-03 17:00 +0100
                Re: Everything is an object in python - object class and type class Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-03 17:29 +0100
                Re: Everything is an object in python - object class and type class BartC <bc@freeuk.com> - 2015-06-03 19:59 +0100
                Re: Everything is an object in python - object class and type class Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-03 21:58 +0100
                Re: Everything is an object in python - object class and type class BartC <bc@freeuk.com> - 2015-06-03 22:33 +0100
                Re: Everything is an object in python - object class and type class Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-06-03 22:49 +0100
                Re: Everything is an object in python - object class and type class BartC <bc@freeuk.com> - 2015-06-04 00:04 +0100
                Re: Everything is an object in python - object class and type class Laura Creighton <lac@openend.se> - 2015-06-04 12:06 +0200
                Re: Everything is an object in python - object class and type class BartC <bc@freeuk.com> - 2015-06-04 13:01 +0100
                Re: Everything is an object in python - object class and type class Laura Creighton <lac@openend.se> - 2015-06-04 15:39 +0200
                Re: Everything is an object in python - object class and type class "Dr. Bigcock" <dreamingforward@gmail.com> - 2015-06-03 21:50 -0700
                Re: Everything is an object in python - object class and type class Eddilbert Macharia <edd.cowan@gmail.com> - 2015-06-03 22:43 -0700
                Re: Everything is an object in python - object class and type class Michael Torrie <torriem@gmail.com> - 2015-06-03 10:36 -0600
                Re: Everything is an object in python - object class and type class BartC <bc@freeuk.com> - 2015-06-03 18:26 +0100
                Re: Everything is an object in python - object class and type class Steven D'Aprano <steve@pearwood.info> - 2015-06-05 00:11 +1000
                Re: Everything is an object in python - object class and type class Terry Reedy <tjreedy@udel.edu> - 2015-06-03 13:17 -0400
              Re: Everything is an object in python - object class and type class Chris Angelico <rosuav@gmail.com> - 2015-06-03 22:19 +1000
              Re: Everything is an object in python - object class and type class Marco Buttu <marco.buttu@gmail.com> - 2015-06-03 14:10 +0200
          Re: Everything is an object in python - object class and type class BartC <bc@freeuk.com> - 2015-06-03 12:13 +0100
          Re: Everything is an object in python - object class and type class Terry Reedy <tjreedy@udel.edu> - 2015-06-03 13:05 -0400
    Re: Everything is an object in python - object class and type class Terry Reedy <tjreedy@udel.edu> - 2015-06-02 12:23 -0400
  Re: Everything is an object in python - object class and type class Eddilbert Macharia <edd.cowan@gmail.com> - 2015-06-03 06:17 -0700

csiph-web