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Re: OT: This Swift thing

References <mailman.10637.1401816526.18130.python-list@python.org> <8738fjkc2w.fsf@dpt-info.u-strasbg.fr> <mailman.10735.1401977435.18130.python-list@python.org> <87tx7zi0i1.fsf@dpt-info.u-strasbg.fr> <lmqn53$4ei$1@ger.gmane.org>
Date 2014-06-06 07:36 +1000
Subject Re: OT: This Swift thing
From Chris Angelico <rosuav@gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.10772.1402004202.18130.python-list@python.org> (permalink)

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On Fri, Jun 6, 2014 at 7:23 AM, Mark Lawrence <breamoreboy@yahoo.co.uk> wrote:
> On 05/06/2014 21:07, Alain Ketterlin wrote:
>>
>> Sturla Molden <sturla.molden@gmail.com> writes:
>>
>>> On 05/06/14 10:14, Alain Ketterlin wrote:
>>>
>>>> Type safety.
>>>
>>> Perhaps. Python has strong type safety.
>>
>> Come on.
>
> I don't understand that comment, please explain.

"Type safety" means many different things to different people. What
Python has is untyped variables, and hierarchically typed objects.
It's impossible to accidentally treat an integer as a float, and have
junk data [1]. It's impossible to accidentally call a base class's
method when you ought to have called the overriding method in the
subclass, which is a risk in C++ [2]. If you mistakenly pass a list to
a function that was expecting an integer, that function will *know*
that it got a list, because objects in Python are rigidly typed.

But some languages stipulate the types that a variable can take, and
that's something Python doesn't do. If you want to say that this
function argument must be an integer, you have to explicitly check it
inside the function. (And the Pythonic thing to do is to *not* check
it, but that's a separate point.) This is something that function
annotations can be used for, but I'm not seeing a huge thrust to make
use of them everywhere. Why not? I suspect because the need for it
just isn't as great as some people think.

ChrisA

[1] Note that in some circumstances, you can (deliberately) fiddle
with an object's type. But you can't just reinterpret the bits in
memory, the way you can in C, by casting a pointer and dereferencing
it. Hence, it's impossible to *accidentally* muck this up.
[2] Again, you can muck things up, by explicitly pulling up a function
from the base class, rather than using method lookup on the object.
But again, you can't do it accidentally.

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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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