Re: Explanation of list reference

References	(11 earlier) <c699d08e-fd66-4aa2-a2b1-d936d7825be5@googlegroups.com> <mailman.6951.1392432144.18130.python-list@python.org> <6e96ba97-8ad0-4dad-9d11-b27bf9b237d0@googlegroups.com> <mailman.6955.1392435220.18130.python-list@python.org> <cf89a78f-3d3a-4df5-9a9a-c0bda8359d8b@googlegroups.com>
Date	2014-02-15 15:37 +1100
Subject	Re: Explanation of list reference
From	Chris Angelico <rosuav@gmail.com>
Newsgroups	comp.lang.python
Message-ID	<mailman.6958.1392439042.18130.python-list@python.org> (permalink)

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On Sat, Feb 15, 2014 at 3:24 PM, Rustom Mody <rustompmody@gmail.com> wrote:
>> I could have three six-sided dice, all made from the same
>> mould, and yet each one is a separate object. If I hold all three in
>> my hand and toss them onto the table, can I recognize which one is
>> which? No, they're identical. Are they distinct objects? Yes.
>
> In the case of physical objects like dice there is a fairly
> unquestionable framing that makes identity straightforward --
> 4-dimensional space-time coordiantes. If the space-time coordinates of
> 2 objects are all equal then the objects are identical, else not.

Not once you roll them, which is why I specifically used dice. This
exact situation comes up in roleplaying games - suppose you want to
get a random number from 0 to 999 (or 1 to 1000, by declaring that a
result of 0 is interpreted as 1000). The most common way to do this is
to roll 10-sided dice for the digits; you can either roll one d10
three times, or three dice all at once. In the latter case, you
somehow need to pre-declare which one is the hundreds digit, which is
the tens, and which is the units, which means you need some way to
distinguish the three dice after you roll them (as you can't recognize
by position). This is why dice exist in a variety of colors [1].
Indistinguishable yet distinct dice... and it's actually possible to
merge all three into a single object (which is what happens when you
roll one three times instead of rolling three once), just as Python is
allowed to do.

By the way, if you get into quantum physics, you can't depend on three
dimensions of space and one of time to distinguish objects. You also
need spin. And I think you also need insanity, because you'll be given
it on arrival if you don't have enough.

ChrisA

[1] Well, that and to look cool. I don't know that any system other
than FATAL requires you to roll d1,000,000 on six dice, so three
colors would normally be sufficient. But it's fun to have the full
spectrum.

Thread

Explanation of list reference dave em <daveandem2000@gmail.com> - 2014-02-14 10:08 -0800
  Re: Explanation of list reference Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2014-02-14 20:26 +0200
    Re: Explanation of list reference dave em <daveandem2000@gmail.com> - 2014-02-14 10:54 -0800
      Re: Explanation of list reference Denis McMahon <denismfmcmahon@gmail.com> - 2014-02-14 19:20 +0000
      Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-14 21:56 +0200
        Re: Explanation of list reference Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-14 13:17 -0700
          Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-14 22:58 +0200
            Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 08:16 +1100
              Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-14 23:43 +0200
                Re: Explanation of list reference Ned Batchelder <ned@nedbatchelder.com> - 2014-02-14 19:00 -0500
                Re: Explanation of list reference dave em <daveandem2000@gmail.com> - 2014-02-14 16:26 -0800
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-15 06:07 +0000
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-15 11:00 +0200
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 11:57 +1100
                Re: Explanation of list reference Rustom Mody <rustompmody@gmail.com> - 2014-02-14 17:55 -0800
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 13:08 +1100
                Re: Explanation of list reference Rustom Mody <rustompmody@gmail.com> - 2014-02-14 18:34 -0800
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 13:42 +1100
                Re: Explanation of list reference Rustom Mody <rustompmody@gmail.com> - 2014-02-14 19:14 -0800
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 14:33 +1100
                Re: Explanation of list reference Rustom Mody <rustompmody@gmail.com> - 2014-02-14 20:24 -0800
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 15:37 +1100
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-15 06:54 +0000
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 18:19 +1100
                Re: Explanation of list reference Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-14 22:20 -0700
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-15 07:03 +0000
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 16:31 +1100
                Re: Explanation of list reference Rustom Mody <rustompmody@gmail.com> - 2014-02-14 22:07 -0800
                Re: Explanation of list reference Ben Finney <ben+python@benfinney.id.au> - 2014-02-15 17:19 +1100
                Re: Explanation of list reference Rustom Mody <rustompmody@gmail.com> - 2014-02-14 22:31 -0800
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 17:23 +1100
                Re: Explanation of list reference Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-15 01:08 -0700
                Re: Explanation of list reference Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-02-15 12:42 +0000
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-15 15:44 +0200
                Re: Explanation of list reference Rustom Mody <rustompmody@gmail.com> - 2014-02-16 06:00 -0800
                Re: Explanation of list reference Ned Batchelder <ned@nedbatchelder.com> - 2014-02-16 11:29 -0500
                Re: Explanation of list reference Rustom Mody <rustompmody@gmail.com> - 2014-02-16 08:50 -0800
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-16 20:01 +0200
                Re: Explanation of list reference Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-02-16 18:36 +0000
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-17 05:52 +0000
                Re: Explanation of list reference Terry Reedy <tjreedy@udel.edu> - 2014-02-15 15:40 -0500
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-16 02:27 +0000
                Re: Explanation of list reference Grant Edwards <invalid@invalid.invalid> - 2014-02-15 19:02 +0000
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-15 06:44 +0000
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 18:05 +1100
                Re: Explanation of list reference Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-02-16 00:29 +1300
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-15 06:15 +0000
                Re: Explanation of list reference Rustom Mody <rustompmody@gmail.com> - 2014-02-14 22:24 -0800
                Re: Explanation of list reference Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-02-16 00:32 +1300
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 22:37 +1100
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-15 11:10 +0200
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-15 10:31 +0000
                Re: Explanation of list reference Christian Gollwitzer <auriocus@gmx.de> - 2014-02-15 10:44 +0100
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-15 12:10 +0200
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-15 10:53 +0000
                Re: Explanation of list reference Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-02-17 11:40 +1300
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-17 05:57 +0000
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 22:21 +1100
                Re: Explanation of list reference Alister <alister.ware@ntlworld.com> - 2014-02-16 19:16 +0000
                Re: Explanation of list reference Ben Finney <ben+python@benfinney.id.au> - 2014-02-15 15:20 +1100
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-15 11:31 +0200
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-15 12:13 +0200
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-15 11:17 +0000
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-15 14:07 +0200
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-15 14:41 +0000
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-15 18:29 +0200
                Re: Explanation of list reference Roy Smith <roy@panix.com> - 2014-02-15 12:02 -0500
                Re: Explanation of list reference Rustom Mody <rustompmody@gmail.com> - 2014-02-15 09:30 -0800
                Re: Explanation of list reference Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-15 11:37 -0700
                Re: Explanation of list reference Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-15 11:45 -0700
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-15 19:05 +0000
                Re: Explanation of list reference Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-15 10:11 -0700
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-15 22:20 +0200
                Re: Explanation of list reference Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-15 14:20 -0700
                Re: Explanation of list reference Rustom Mody <rustompmody@gmail.com> - 2014-02-15 09:47 -0800
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-15 19:17 +0000
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-15 23:01 +0200
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-16 02:25 +0000
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-16 13:18 +0200
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 22:31 +1100
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-15 10:40 +0000
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 22:17 +1100
            Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-14 23:20 +0200
            Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-16 10:08 +0200
              Re: Explanation of list reference Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-16 01:28 -0700
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-16 12:52 +0200
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-16 22:24 +1100
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-16 12:04 +0000
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-16 18:17 +0200
              Re: Explanation of list reference Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2014-02-16 10:35 +0200
              Re: Explanation of list reference Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-16 01:35 -0700
              Re: Explanation of list reference Alan Bawden <alan@scooby-doo.csail.mit.edu> - 2014-02-16 03:38 -0500
              Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-16 08:40 +0000
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-16 21:18 +1100
              Re: Explanation of list reference Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-02-16 12:10 -0500
        Re: Explanation of list reference Ned Batchelder <ned@nedbatchelder.com> - 2014-02-14 15:45 -0500
      Re: Explanation of list reference Ian Kelly <ian.g.kelly@gmail.com> - 2014-02-14 13:12 -0700
      Re: Explanation of list reference Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2014-02-14 22:36 +0200
        Re: Explanation of list reference Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-02-16 01:03 +1300
        Re: Explanation of list reference Ben Finney <ben+python@benfinney.id.au> - 2014-02-15 23:21 +1100
  Re: Explanation of list reference Ned Batchelder <ned@nedbatchelder.com> - 2014-02-14 13:42 -0500
  Re: Explanation of list reference Ryan Gonzalez <rymg19@gmail.com> - 2014-02-14 12:31 -0600
    Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-15 05:36 +0000
      Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 17:07 +1100
        Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-15 06:48 +0000
          Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 17:57 +1100
            Re: Explanation of list reference Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-02-16 01:18 +1300
              Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-15 23:24 +1100
                Re: Explanation of list reference Marko Rauhamaa <marko@pacujo.net> - 2014-02-15 15:25 +0200
                Re: Explanation of list reference Ben Finney <ben+python@benfinney.id.au> - 2014-02-16 00:59 +1100
                Re: Explanation of list reference Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-02-17 11:54 +1300
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-17 10:02 +1100
                Re: Explanation of list reference Roy Smith <roy@panix.com> - 2014-02-16 18:46 -0500
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-17 12:26 +1100
                Re: Explanation of list reference Ben Finney <ben+python@benfinney.id.au> - 2014-02-17 10:05 +1100
                Re: Explanation of list reference Roy Smith <roy@panix.com> - 2014-02-16 18:43 -0500
                Re: Explanation of list reference Ben Finney <ben+python@benfinney.id.au> - 2014-02-17 11:04 +1100
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-17 06:31 +0000
                Re: Explanation of list reference Rustom Mody <rustompmody@gmail.com> - 2014-02-17 05:43 -0800
                Re: Explanation of list reference Ned Batchelder <ned@nedbatchelder.com> - 2014-02-16 20:43 -0500
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-17 12:59 +1100
                Re: Explanation of list reference Roy Smith <roy@panix.com> - 2014-02-16 22:28 -0500
                Re: Explanation of list reference Ben Finney <ben+python@benfinney.id.au> - 2014-02-17 14:52 +1100
                Re: Explanation of list reference Rustom Mody <rustompmody@gmail.com> - 2014-02-16 20:35 -0800
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-17 08:03 +0000
                Re: Explanation of list reference Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-02-17 06:21 +0000
                Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-17 18:11 +1100
                Re: Explanation of list reference Rotwang <sg552@hotmail.co.uk> - 2014-02-17 18:24 +0000
          Re: Explanation of list reference Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-02-15 14:30 -0500
  Re: Explanation of list reference Terry Reedy <tjreedy@udel.edu> - 2014-02-14 16:37 -0500
  Re: Explanation of list reference pecore@pascolo.net - 2014-02-14 23:34 +0100
  Re: Explanation of list reference Christian Gollwitzer <auriocus@gmx.de> - 2014-02-15 10:38 +0100
  Re: Explanation of list reference Ben Finney <ben+python@benfinney.id.au> - 2014-02-16 01:20 +1100
  Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-16 01:26 +1100
  Re: Explanation of list reference Joshua Landau <joshua@landau.ws> - 2014-02-15 20:44 +0000
  Re: Explanation of list reference Chris Angelico <rosuav@gmail.com> - 2014-02-16 09:27 +1100

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