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Re: Assignment Versus Equality

Path csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From Chris Angelico <rosuav@gmail.com>
Newsgroups comp.lang.python
Subject Re: Assignment Versus Equality
Date Wed, 29 Jun 2016 15:07:03 +1000
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On Wed, Jun 29, 2016 at 2:51 PM, Lawrence D’Oliveiro
<lawrencedo99@gmail.com> wrote:
> On Wednesday, June 29, 2016 at 4:20:24 PM UTC+12, Chris Angelico wrote:
>>> https://www.jwz.org/blog/2010/10/every-day-i-learn-something-new-and-stupid/
>>
>> """It would also be reasonable to assume that any sane language
>> runtime would have integers transparently degrade to BIGNUMs, making
>> the choice of accuracy over speed, but of course that almost never
>> happens..."""
>>
>> Python 2 did this, but Python 3 doesn't.
>
> Huh?
>
>     ldo@theon:~> python3
>     Python 3.5.1+ (default, Jun 10 2016, 09:03:40)
>     [GCC 5.4.0 20160603] on linux
>     Type "help", "copyright", "credits" or "license" for more information.
>     >>> 2 ** 64
>     18446744073709551616
>     >>> type(2 ** 64)
>     <class 'int'>

The transparent shift from machine-word to bignum is what no longer
exists. Both Py2 and Py3 will store large integers as bignums; Py2 has
two separate data types (int and long), with ints generally
outperforming longs, but Py3 simply has one (called int, but
functionally like Py2's long), and does everything with bignums.
There's no longer a boundary - instead, everything gets the "bignum
tax". How steep is that tax? I'm not sure, but microbenchmarking shows
that there definitely is one. How bad is it in real-world code? No
idea.

ChrisA

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Thread

Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-26 00:36 -0700
  Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-26 11:48 +0100
    Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-26 23:21 +1000
      Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-26 07:26 -0700
        Re: Assignment Versus Equality Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-06-26 11:31 -0400
      Re: Assignment Versus Equality Christopher Reimer <christopher_reimer@icloud.com> - 2016-06-26 11:47 -0700
      Re: Assignment Versus Equality Michael Torrie <torriem@gmail.com> - 2016-06-26 15:28 -0600
      Re: Assignment Versus Equality Bob Gailer <bgailer@gmail.com> - 2016-06-27 08:22 -0400
        Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-27 05:48 -0700
          Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-27 23:28 +1000
            Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-27 16:58 +0300
            Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-27 07:23 -0700
              Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-28 11:05 +1000
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-27 21:31 -0700
                Re: Assignment Versus Equality Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-28 15:42 +1000
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-28 16:04 +1000
                Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-28 09:12 +0300
                Re: Assignment Versus Equality Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-06-28 11:04 +0300
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-27 23:09 -0700
                Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-28 00:12 -0700
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-28 17:26 +1000
                Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-28 01:49 -0700
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-28 20:34 +1000
                Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-28 17:42 -0700
                Re: Assignment Versus Equality Random832 <random832@fastmail.com> - 2016-06-28 10:13 -0400
                Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-28 19:39 +0300
                Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-28 19:41 +0300
                Re: Assignment Versus Equality Random832 <random832@fastmail.com> - 2016-06-28 13:19 -0400
                Re: Assignment Versus Equality Ian Kelly <ian.g.kelly@gmail.com> - 2016-06-28 12:27 -0600
                Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-28 22:40 +0300
                Re: Assignment Versus Equality Gene Heskett <gheskett@shentel.net> - 2016-06-28 16:59 -0400
                Re: Assignment Versus Equality Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-30 12:29 +1200
                Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-30 12:50 +1000
                Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-30 09:22 +0300
                Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-29 12:27 +1000
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-28 20:52 -0700
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-28 21:03 -0700
                Re: Assignment Versus Equality Random832 <random832@fastmail.com> - 2016-06-29 00:52 -0400
              Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-27 18:14 -0700
            Re: Assignment Versus Equality Gene Heskett <gheskett@shentel.net> - 2016-06-27 11:21 -0400
          Re: Assignment Versus Equality Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-06-27 20:04 -0400
    Re: Assignment Versus Equality Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-06-26 11:21 -0400
      Re: Assignment Versus Equality Cousin Stanley <HooDunnit@didly42KahZidly.net> - 2016-06-26 08:47 -0700
        Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-26 16:56 +0100
          Re: Assignment Versus Equality Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-27 11:38 +1200
          Re: Assignment Versus Equality Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-06-27 07:30 -0400
            Re: Assignment Versus Equality Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-28 18:17 +1200
          Re: Assignment Versus Equality Grant Edwards <grant.b.edwards@gmail.com> - 2016-06-27 13:59 +0000
            Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-27 17:09 +0300
              Re: Assignment Versus Equality sohcahtoa82@gmail.com - 2016-06-27 17:33 -0700
                Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-28 07:25 +0300
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-27 23:54 -0700
            Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-27 07:10 -0700
              Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-29 12:35 +1000
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-29 14:19 +1000
                Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-28 21:51 -0700
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-29 15:07 +1000
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-28 22:55 -0700
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-29 16:26 +1000
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-28 23:33 -0700
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-28 23:37 -0700
                Re: Assignment Versus Equality Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-29 15:26 +1000
                Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-28 22:51 -0700
                Re: Assignment Versus Equality Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-06-29 16:45 +1000
                Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-29 01:07 -0700
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-29 18:09 +1000
                Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-29 22:36 +1000
                Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-29 14:24 +0100
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-29 23:35 +1000
                Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-29 15:47 +0100
                Re: Assignment Versus Equality Chris Angelico <rosuav@gmail.com> - 2016-06-29 23:34 +1000
                Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-29 10:49 +0100
                Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-29 02:56 -0700
                Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-29 11:10 +0100
                Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-29 03:24 -0700
            Re: Assignment Versus Equality Alain Ketterlin <alain@universite-de-strasbourg.fr.invalid> - 2016-06-27 16:48 +0200
              Re: Assignment Versus Equality Rustom Mody <rustompmody@gmail.com> - 2016-06-27 22:00 -0700
            Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-28 11:34 +1000
          Re: Assignment Versus Equality MRAB <python@mrabarnett.plus.com> - 2016-06-27 16:27 +0100
            Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-27 14:56 -0700
            Re: Assignment Versus Equality Lawrence D’Oliveiro <lawrencedo99@gmail.com> - 2016-06-27 15:45 -0700
              Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-28 00:08 +0100
                Re: Assignment Versus Equality Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2016-06-27 20:11 -0400
                Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-28 11:35 +0100
                Re: Assignment Versus Equality Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-28 18:59 +1200
            Re: Assignment Versus Equality Steven D'Aprano <steve@pearwood.info> - 2016-06-28 11:28 +1000
          Re: Assignment Versus Equality Grant Edwards <grant.b.edwards@gmail.com> - 2016-06-27 15:42 +0000
      Re: Assignment Versus Equality Marko Rauhamaa <marko@pacujo.net> - 2016-06-26 19:11 +0300
    Re: Assignment Versus Equality MRAB <python@mrabarnett.plus.com> - 2016-06-26 16:41 +0100
      Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-26 17:08 +0100
    Re: Assignment Versus Equality Christopher Reimer <christopher_reimer@icloud.com> - 2016-06-26 11:53 -0700
      Re: Assignment Versus Equality Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-27 11:41 +1200
    Re: Assignment Versus Equality Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-27 11:22 +1200
      Re: Assignment Versus Equality BartC <bc@freeuk.com> - 2016-06-27 00:39 +0100
        Re: Assignment Versus Equality Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-06-28 18:15 +1200

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