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Re: OT: This Swift thing

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Date Fri, 6 Jun 2014 13:27:27 +1000
Subject Re: OT: This Swift thing
From Chris Angelico <rosuav@gmail.com>
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On Fri, Jun 6, 2014 at 1:16 PM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> On Fri, 06 Jun 2014 09:21:26 +1000, Chris Angelico wrote:
>
>> On Fri, Jun 6, 2014 at 9:02 AM, Sturla Molden <sturla.molden@gmail.com>
>> wrote:
>>> You cannot spoof the type of an object in Python.
>>
>> Not without fiddling around. Python 3.4 on win32:
> [...]
>>>>> x = Foo()
>>>>> x.spam()
>> <__main__.Foo object at 0x0169AB10> spams
>>>>> x.__class__ = Bar
>>>>> x.spam()
>> <__main__.Bar object at 0x0169AB10> eats spam
>>
>> The thing has the same id (as shown in its repr), but has changed class.
>
> That's not spoofing types. That is a language feature: within limits,
> instances can change their type. It has been around for a long, long
> time, back to Python 1.5 or older, and it has real-world use-cases:
>
> http://code.activestate.com/recipes/68429-ring-buffer/

True, it's not *spoofing*, in the same way that this C code is:

float x = 3.14159;
int y = *(int *)&x;

And I'm aware that it's a language feature (why else would it be
specifically limited with a clear exception when you try to assign
something you can't?). So's the C-level fiddling, albeit for different
reasons and in different ways. Anyway, I was broadly agreeing -
Python's type system is "objects have types", rather than "stuff is in
memory and data types are just how you look at it". It just happens to
be possible to fiddle if you want to :)

ChrisA

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Thread

OT: This Swift thing Sturla Molden <sturla.molden@gmail.com> - 2014-06-03 17:28 +0000
  Re: OT: This Swift thing Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-06-05 10:14 +0200
    Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-05 18:38 +1000
      Re: OT: This Swift thing Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-06-05 11:42 +0200
        Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-05 22:48 +1000
          Re: OT: This Swift thing Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-06-05 22:27 +0200
            Re: OT: This Swift thing Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-06-05 22:28 +0100
            Re: OT: This Swift thing Sturla Molden <sturla.molden@gmail.com> - 2014-06-05 23:03 +0000
              Re: OT: This Swift thing Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-06-06 13:21 +0200
                Re: OT: This Swift thing Sturla Molden <sturla.molden@gmail.com> - 2014-06-07 01:54 +0000
                Re: OT: This Swift thing Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-06-07 10:20 +0200
                Re: OT: This Swift thing Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-06-07 09:32 +0100
                Re: OT: This Swift thing Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-06-07 11:54 +0200
                Re: OT: This Swift thing Johannes Bauer <dfnsonfsduifb@gmx.de> - 2014-06-15 10:55 +0200
                Re: OT: This Swift thing Roy Smith <roy@panix.com> - 2014-06-07 08:52 -0400
                Re: OT: This Swift thing Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-06-07 11:13 -0400
                Re: OT: This Swift thing Roy Smith <roy@panix.com> - 2014-06-07 11:54 -0400
                Re: OT: This Swift thing Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-06-07 17:10 -0400
                Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-07 23:32 +0000
            Re: OT: This Swift thing Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-06-06 00:41 +0100
            Re: OT: This Swift thing Sturla Molden <sturla.molden@gmail.com> - 2014-06-06 01:54 +0200
              Re: OT: This Swift thing Roy Smith <roy@panix.com> - 2014-06-05 20:13 -0400
                Re: OT: This Swift thing Sturla Molden <sturla.molden@gmail.com> - 2014-06-06 02:35 +0200
              Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-06 05:45 +0000
              Re: OT: This Swift thing Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-06-06 13:39 +0200
                Re: OT: This Swift thing Sturla Molden <sturla.molden@gmail.com> - 2014-06-07 01:54 +0000
            Re: OT: This Swift thing Sturla Molden <sturla.molden@gmail.com> - 2014-06-06 02:03 +0200
    Re: OT: This Swift thing wxjmfauth@gmail.com - 2014-06-05 02:09 -0700
    Re: OT: This Swift thing Sturla Molden <sturla.molden@gmail.com> - 2014-06-05 16:10 +0200
      Re: OT: This Swift thing Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-06-05 22:07 +0200
        Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-06 06:18 +1000
          Re: OT: This Swift thing Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-06-05 23:12 +0200
            Re: OT: This Swift thing Sturla Molden <sturla.molden@gmail.com> - 2014-06-05 23:02 +0000
        Re: OT: This Swift thing Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-06-05 22:23 +0100
          Re: OT: This Swift thing Marko Rauhamaa <marko@pacujo.net> - 2014-06-06 00:53 +0300
            Re: OT: This Swift thing Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-06-05 23:13 +0100
              Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-06 02:52 +0000
            Re: OT: This Swift thing Johannes Bauer <dfnsonfsduifb@gmx.de> - 2014-06-15 11:33 +0200
              Re: OT: This Swift thing Marko Rauhamaa <marko@pacujo.net> - 2014-06-15 16:10 +0300
        Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-06 07:36 +1000
          Re: OT: This Swift thing Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-06-06 13:20 +0200
            Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-06 22:23 +1000
            Re: OT: This Swift thing Christian Gollwitzer <auriocus@gmx.de> - 2014-06-07 09:30 +0200
        Re: OT: This Swift thing Terry Reedy <tjreedy@udel.edu> - 2014-06-05 18:18 -0400
          Re: OT: This Swift thing Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-06-06 13:11 +0200
            Re: OT: This Swift thing Terry Reedy <tjreedy@udel.edu> - 2014-06-06 13:06 -0400
            Re: OT: This Swift thing alex23 <wuwei23@gmail.com> - 2014-06-10 15:32 +1000
        Re: OT: This Swift thing Sturla Molden <sturla.molden@gmail.com> - 2014-06-05 23:02 +0000
        Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-05 23:08 +0000
        Re: OT: This Swift thing Sturla Molden <sturla.molden@gmail.com> - 2014-06-05 23:08 +0000
        Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-06 09:21 +1000
          Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-06 03:16 +0000
            Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-06 13:27 +1000
    Re: OT: This Swift thing Michael Torrie <torriem@gmail.com> - 2014-06-05 08:33 -0600
    Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-06 01:44 +1000
    Re: OT: This Swift thing Sturla Molden <sturla.molden@gmail.com> - 2014-06-05 18:09 +0200
    Re: OT: This Swift thing Michael Torrie <torriem@gmail.com> - 2014-06-05 11:18 -0600
      Re: OT: This Swift thing Mark H Harris <harrismh777@gmail.com> - 2014-06-05 13:49 -0500
    Re: OT: This Swift thing Travis Griggs <travisgriggs@gmail.com> - 2014-06-05 23:28 -0700
      Re: OT: This Swift thing Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-06-06 10:25 +0200
    Re: OT: This Swift thing Michael Torrie <torriem@gmail.com> - 2014-06-06 20:41 -0600
      Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-07 04:57 +0000
        Re: OT: This Swift thing Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-06-07 11:23 -0400
          Re: OT: This Swift thing Roy Smith <roy@panix.com> - 2014-06-07 11:51 -0400
            Re: OT: This Swift thing Marko Rauhamaa <marko@pacujo.net> - 2014-06-07 19:18 +0300
              Re: OT: This Swift thing MRAB <python@mrabarnett.plus.com> - 2014-06-08 15:10 +0100
        Re: OT: This Swift thing Michael Torrie <torriem@gmail.com> - 2014-06-07 11:37 -0600
          Re: OT: This Swift thing Roy Smith <roy@panix.com> - 2014-06-07 14:11 -0400
            Re: OT: This Swift thing Michael Torrie <torriem@gmail.com> - 2014-06-07 13:00 -0600
              Re: OT: This Swift thing Roy Smith <roy@panix.com> - 2014-06-07 15:11 -0400
            Re: OT: This Swift thing Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-06-07 17:59 -0400
              Re: OT: This Swift thing Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-06-08 13:25 +1200
            Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-07 23:38 +0000
              Re: OT: This Swift thing Roy Smith <roy@panix.com> - 2014-06-07 20:09 -0400
                Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-08 10:37 +1000
                Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-08 03:50 +0000
                Re: OT: This Swift thing Roy Smith <roy@panix.com> - 2014-06-08 10:51 -0400
                Re: OT: This Swift thing Gene Heskett <gheskett@wdtv.com> - 2014-06-08 11:21 -0400
                Re: OT: This Swift thing Roy Smith <roy@panix.com> - 2014-06-08 12:09 -0400
                Re: OT: This Swift thing Gene Heskett <gheskett@wdtv.com> - 2014-06-08 13:14 -0400
                Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-09 03:25 +1000
                Re: OT: This Swift thing Sturla Molden <sturla.molden@gmail.com> - 2014-06-08 18:09 +0000
                Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-09 04:16 +1000
                Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-09 01:44 +0000
                Re: OT: This Swift thing Rustom Mody <rustompmody@gmail.com> - 2014-06-08 19:24 -0700
                Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-09 04:20 +0000
                Re: OT: This Swift thing Rustom Mody <rustompmody@gmail.com> - 2014-06-08 23:32 -0700
                Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-09 09:27 +0000
                Re: OT: This Swift thing Rustom Mody <rustompmody@gmail.com> - 2014-06-09 04:51 -0700
                Re: OT: This Swift thing Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-06-11 19:41 +1200
                Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-11 13:44 +0000
                Re: OT: This Swift thing Rustom Mody <rustompmody@gmail.com> - 2014-06-11 08:28 -0700
                Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-12 02:08 +0000
                Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-12 12:16 +1000
                Re: OT: This Swift thing Steven D'Aprano <steve@pearwood.info> - 2014-06-12 09:06 +0000
                Re: OT: This Swift thing alister <alister.nospam.ware@ntlworld.com> - 2014-06-12 09:34 +0000
                Re: OT: This Swift thing Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-06-12 23:32 +1200
                Re: OT: This Swift thing Anssi Saari <as@sci.fi> - 2014-06-16 13:57 +0300
                Re: OT: This Swift thing Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-06-17 10:12 +1200
                Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-17 08:34 +1000
                Re: OT: This Swift thing alister <alister.nospam.ware@ntlworld.com> - 2014-06-17 11:16 +0000
                Re: OT: This Swift thing Bob Martin <bob.martin@excite.com> - 2014-06-18 07:41 +0100
                Re: OT: This Swift thing Rustom Mody <rustompmody@gmail.com> - 2014-06-12 05:54 -0700
                Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-12 17:04 +0000
                Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-13 03:18 +1000
                Re: OT: This Swift thing Rustom Mody <rustompmody@gmail.com> - 2014-06-12 18:59 -0700
                Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-13 03:26 +0000
                Re: OT: This Swift thing Gene Heskett <gheskett@wdtv.com> - 2014-06-12 14:43 -0400
                Re: OT: This Swift thing albert@spenarnc.xs4all.nl (Albert van der Horst) - 2014-06-27 23:21 +0000
                Re: OT: This Swift thing Joshua Landau <joshua@landau.ws> - 2014-06-15 02:51 +0100
                Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-15 03:33 +0000
                Re: OT: This Swift thing Gene Heskett <gheskett@wdtv.com> - 2014-06-09 10:11 -0400
                Re: OT: This Swift thing Marko Rauhamaa <marko@pacujo.net> - 2014-06-09 17:27 +0300
                Re: OT: This Swift thing Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-06-11 18:56 +1200
                Re: OT: This Swift thing Roy Smith <roy@panix.com> - 2014-06-09 09:14 -0400
                Re: OT: This Swift thing Michael Torrie <torriem@gmail.com> - 2014-06-09 07:56 -0600
                Re: OT: This Swift thing Marko Rauhamaa <marko@pacujo.net> - 2014-06-09 17:30 +0300
                Re: OT: This Swift thing Rustom Mody <rustompmody@gmail.com> - 2014-06-08 19:35 -0700
                Re: OT: This Swift thing Chris Angelico <rosuav@gmail.com> - 2014-06-09 12:23 +1000
                Re: OT: This Swift thing Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-06-11 19:50 +1200
                Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-11 12:34 +0000
                Re: OT: This Swift thing Roy Smith <roy@panix.com> - 2014-06-11 08:48 -0400
                Re: OT: This Swift thing Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-06-11 20:17 -0400
                Re: OT: This Swift thing Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-06-12 01:25 +0000
                Re: OT: This Swift thing Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-06-12 14:11 +1200
                Re: OT: This Swift thing Gene Heskett <gheskett@wdtv.com> - 2014-06-11 23:06 -0400
                Re: OT: This Swift thing Roy Smith <roy@panix.com> - 2014-06-13 08:55 -0400
                Re: OT: This Swift thing Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-06-09 21:51 -0400
                Re: OT: This Swift thing Carlos Anselmo Dias <carlos@premium-sponsor.com> - 2014-06-08 18:56 +0100
                Re: OT: This Swift thing Sturla Molden <sturla.molden@gmail.com> - 2014-06-08 23:34 +0000
                Re: OT: This Swift thing Rustom Mody <rustompmody@gmail.com> - 2014-06-08 19:32 -0700
          Re: OT: This Swift thing Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-06-08 13:09 +1200

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