Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #98495

Re: Question about math.pi is mutable

Path csiph.com!news.swapon.de!fu-berlin.de!uni-berlin.de!not-for-mail
From Ben Finney <ben+python@benfinney.id.au>
Newsgroups comp.lang.python
Subject Re: Question about math.pi is mutable
Date Mon, 09 Nov 2015 11:50:57 +1100
Lines 42
Message-ID <mailman.158.1447030266.16136.python-list@python.org> (permalink)
References <n1kshk$brb$1@dont-email.me> <87d1vlzy4p.fsf@elektro.pacujo.net> <878u69zxww.fsf@elektro.pacujo.net> <n1l3kd$5ma$1@dont-email.me> <563eba85$0$1611$c3e8da3$5496439d@news.astraweb.com> <n1n8mc$33l$1@dont-email.me> <87ziyowy83.fsf@elektro.pacujo.net> <n1nb0f$atn$1@dont-email.me> <mailman.135.1446998410.16136.python-list@python.org> <n1o25a$3s3$1@dont-email.me> <mailman.142.1447005691.16136.python-list@python.org> <n1o5sl$joc$1@dont-email.me> <mailman.152.1447024427.16136.python-list@python.org> <n1on71$san$1@dont-email.me> <8537wghwjb.fsf@benfinney.id.au> <CAPTjJmo=4p3DnvcLY_whdzaiy1t-sTyok20U9M0nQsNCg9_E=Q@mail.gmail.com> <85y4e8ggrj.fsf@benfinney.id.au> <CAPTjJmqaTQy397xgSjQsC2Bu8mxDQTvGsryp0e6nDk6Le688=A@mail.gmail.com>
Mime-Version 1.0
Content-Type text/plain; charset=utf-8
Content-Transfer-Encoding 8bit
X-Trace news.uni-berlin.de p02oUfrKrKaJAWZrZLivVA3t1hxYYmVphtzW9eFCqLUg==
Cancel-Lock sha1:abXUgqc9hdDzKVfZXJCCao8cNXw=
Return-Path <python-python-list@m.gmane.org>
X-Original-To python-list@python.org
Delivered-To python-list@mail.python.org
X-Spam-Status OK 0.001
X-Spam-Evidence '*H*': 1.00; '*S*': 0.00; 'compiler': 0.05; 'subject:Question': 0.05; 'sufficient': 0.05; 'attributes': 0.07; 'falls': 0.09; 'immutable': 0.09; 'name)': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'advocating': 0.16; 'assumptions': 0.16; 'received:80.91.229.3': 0.16; 'received:io': 0.16; 'received:plane.gmane.org': 0.16; 'received:psf.io': 0.16; 'uses,': 0.16; 'wrote:': 0.16; 'compilation': 0.18; "shouldn't": 0.18; 'tests': 0.18; '2015': 0.20; 'not,': 0.22; 'saying': 0.22; 'disable': 0.22; 'uses.': 0.22; 'am,': 0.23; 'code,': 0.23; 'decide': 0.23; 'mon,': 0.24; 'module': 0.25; 'testing': 0.25; 'header:User-Agent:1': 0.26; 'header:X-Complaints-To:1': 0.26; 'chris': 0.26; 'separate': 0.27; 'question': 0.27; '(my': 0.29; 'itself,': 0.29; 'path,': 0.29; "i'm": 0.30; 'code': 0.30; 'agreed': 0.31; 'run': 0.33; 'that,': 0.34; 'nov': 0.35; 'problem.': 0.35; 'but': 0.36; 'should': 0.36; 'needed': 0.36; 'depends': 0.36; 'to:addr:python-list': 0.36; 'subject:: ': 0.37; 'being': 0.37; 'received:org': 0.37; 'means': 0.39; 'test': 0.39; 'enough': 0.39; 'to:addr:python.org': 0.40; 'chance': 0.60; 'your': 0.60; 'back': 0.62; 'making': 0.62; 'between': 0.65; '\xe2\x80\x93': 0.72; '_o__)': 0.84; 'cripple': 0.84; 'distinguish': 0.84; 'optimisation': 0.84; 'received:125': 0.84; '\xe2\x80\x9cwe': 0.84; 'shadow': 0.91
X-Injected-Via-Gmane http://gmane.org/
X-Gmane-NNTP-Posting-Host jigong.madmonks.org
X-Public-Key-ID 0xAC128405
X-Public-Key-Fingerprint 517C F14B B2F3 98B0 CB35 4855 B8B2 4C06 AC12 8405
X-Public-Key-URL http://www.benfinney.id.au/contact/bfinney-pubkey.asc
X-Post-From Ben Finney <bignose+hates-spam@benfinney.id.au>
User-Agent Gnus/5.13 (Gnus v5.13) Emacs/24.4 (gnu/linux)
X-BeenThere python-list@python.org
X-Mailman-Version 2.1.20+
Precedence list
List-Id General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe <https://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive <http://mail.python.org/pipermail/python-list/>
List-Post <mailto:python-list@python.org>
List-Help <mailto:python-list-request@python.org?subject=help>
List-Subscribe <https://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Xref csiph.com comp.lang.python:98495

Show key headers only | View raw

Chris Angelico <rosuav@gmail.com> writes:

> On Mon, Nov 9, 2015 at 11:26 AM, Ben Finney <ben+python@benfinney.id.au> wrote:
> > Chris Angelico <rosuav@gmail.com> writes:
> >
> >> Testing/mocking is a completely separate consideration (eg you can
> >> inject a shadow for a built-in name)
> >
> > Not for the purpose of making compiler optimisations, as BartC is
> > advocating. […] since those optimisations would cripple perfectly
> > normal test code, that should be sufficient to quash the desire to
> > make them.
>
> But I distinguish between crippling *performance* and crippling
> *functionality*. If the compiler optimizations are defeated, so the
> test suite falls back on the slow path, that means your tests run
> slower. Unless you're testing the optimizer itself, this shouldn't be
> a problem.

You misunderstand me. I'm not saying the optimisations would be
crippled. I am saying that, in order to achieve those optimisations, the
*test code* would be crippled.

I am pointing out that the assumption necessary for the optimisation
BartC is advocating – the optimisation of module attributes to be
immutable after compilation – depends on crippling the *functionality*
needed for many uses, including test code uses.

Since the compiler should not be in the position of deciding whether
code is test code or not, it cannot use that criterion to decide whether
to enable or disable the optimisation.

So either the optimisation should never be enabled (my perference), or
test code will unwittingly be crippled by the assumptions needed for
that optimisation.

-- 
 \     “We are all agreed that your theory is crazy. The question that |
  `\      divides us is whether it is crazy enough to have a chance of |
_o__)            being correct.” —Niels Bohr (to Wolfgang Pauli), 1958 |
Ben Finney

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Question about math.pi is mutable "wangq@travelsky.com" <wangq@travelsky.com> - 2015-11-06 10:33 +0800
  Re: Question about math.pi is mutable Bartc <bc@freeuk.com> - 2015-11-06 12:30 +0000
    Re: Question about math.pi is mutable Lorenzo Sutton <lorenzofsutton@gmail.com> - 2015-11-06 17:12 +0100
      Re: Question about math.pi is mutable Bartc <bc@freeuk.com> - 2015-11-06 19:30 +0000
        Re: Question about math.pi is mutable Chris Angelico <rosuav@gmail.com> - 2015-11-07 06:40 +1100
          Re: Question about math.pi is mutable Christian Gollwitzer <auriocus@gmx.de> - 2015-11-06 20:59 +0100
          Re: Question about math.pi is mutable Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-11-06 23:19 +0100
            Re: Question about math.pi is mutable Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-11-07 00:48 +0100
            Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-07 13:00 +1100
        Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-07 14:43 +1100
          Re: Question about math.pi is mutable Bartc <bc@freeuk.com> - 2015-11-07 11:23 +0000
            Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-07 22:35 +1100
              Re: Question about math.pi is mutable Bartc <bc@freeuk.com> - 2015-11-07 11:57 +0000
                Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-07 23:15 +1100
                Re: Question about math.pi is mutable Bartc <bc@freeuk.com> - 2015-11-07 13:00 +0000
                Re: Question about math.pi is mutable Laura Creighton <lac@openend.se> - 2015-11-07 15:09 +0100
                Re: Question about math.pi is mutable Marko Rauhamaa <marko@pacujo.net> - 2015-11-07 16:23 +0200
                Re: Question about math.pi is mutable Marko Rauhamaa <marko@pacujo.net> - 2015-11-07 16:28 +0200
                Re: Question about math.pi is mutable Bartc <bc@freeuk.com> - 2015-11-07 15:01 +0000
                Re: Question about math.pi is mutable Marko Rauhamaa <marko@pacujo.net> - 2015-11-07 19:46 +0200
                Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-08 14:07 +1100
                Re: Question about math.pi is mutable Random832 <random832@fastmail.com> - 2015-11-08 01:29 -0500
                Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-08 13:59 +1100
                Re: Question about math.pi is mutable Bartc <bc@freeuk.com> - 2015-11-08 10:40 +0000
                Re: Question about math.pi is mutable Marko Rauhamaa <marko@pacujo.net> - 2015-11-08 13:02 +0200
                Re: Question about math.pi is mutable BartC <bc@freeuk.com> - 2015-11-08 11:19 +0000
                Re: Question about math.pi is mutable Marko Rauhamaa <marko@pacujo.net> - 2015-11-08 13:50 +0200
                Re: Question about math.pi is mutable BartC <bc@freeuk.com> - 2015-11-08 12:39 +0000
                Re: Question about math.pi is mutable Marko Rauhamaa <marko@pacujo.net> - 2015-11-08 14:43 +0200
                Re: Question about math.pi is mutable BartC <bc@freeuk.com> - 2015-11-08 13:42 +0000
                Re: Question about math.pi is mutable Marko Rauhamaa <marko@pacujo.net> - 2015-11-08 16:33 +0200
                Re: Question about math.pi is mutable Chris Angelico <rosuav@gmail.com> - 2015-11-09 02:11 +1100
                Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-09 11:58 +1100
                Re: Question about math.pi is mutable Chris Angelico <rosuav@gmail.com> - 2015-11-08 23:28 +1100
                Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-09 11:35 +1100
                Re: Question about math.pi is mutable Michael Torrie <torriem@gmail.com> - 2015-11-08 08:59 -0700
                Re: Question about math.pi is mutable BartC <bc@freeuk.com> - 2015-11-08 17:54 +0000
                Re: Question about math.pi is mutable Chris Angelico <rosuav@gmail.com> - 2015-11-09 05:01 +1100
                Re: Question about math.pi is mutable BartC <bc@freeuk.com> - 2015-11-08 18:58 +0000
                Re: Question about math.pi is mutable Ian Kelly <ian.g.kelly@gmail.com> - 2015-11-08 12:51 -0700
                Re: Question about math.pi is mutable Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-11-08 18:13 -0500
                Re: Question about math.pi is mutable BartC <bc@freeuk.com> - 2015-11-08 23:54 +0000
                Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-09 11:00 +1100
                Re: Question about math.pi is mutable BartC <bc@freeuk.com> - 2015-11-09 00:11 +0000
                Re: Question about math.pi is mutable Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2015-11-09 08:18 -0500
                Re: Question about math.pi is mutable Chris Angelico <rosuav@gmail.com> - 2015-11-09 11:04 +1100
                Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-09 11:26 +1100
                Re: Question about math.pi is mutable Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-11-09 21:29 +1300
                Re: Question about math.pi is mutable Chris Angelico <rosuav@gmail.com> - 2015-11-09 11:36 +1100
                Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-09 11:50 +1100
                Re: Question about math.pi is mutable Chris Angelico <rosuav@gmail.com> - 2015-11-09 11:56 +1100
                Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-09 12:04 +1100
                Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-09 22:22 +1100
                Re: Question about math.pi is mutable Random832 <random832@fastmail.com> - 2015-11-09 10:32 -0500
                Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-10 06:45 +1100
                Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-10 13:37 +1100
                Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-10 17:10 +1100
                Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-10 22:34 +1100
                Re: Question about math.pi is mutable BartC <bc@freeuk.com> - 2015-11-10 13:26 +0000
                Re: Question about math.pi is mutable Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-11-11 18:38 +1100
                Re: Question about math.pi is mutable Marko Rauhamaa <marko@pacujo.net> - 2015-11-11 10:30 +0200
                Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-11 22:20 +1100
                Re: Question about math.pi is mutable Terry Reedy <tjreedy@udel.edu> - 2015-11-10 03:30 -0500
                Re: Question about math.pi is mutable Laura Creighton <lac@openend.se> - 2015-11-10 11:33 +0100
                Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-10 23:14 +1100
                Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-11 12:10 +1100
                Re: Question about math.pi is mutable Laura Creighton <lac@openend.se> - 2015-11-09 21:07 +0100
                Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-10 10:21 +1100
                Re: Question about math.pi is mutable BartC <bc@freeuk.com> - 2015-11-09 16:54 +0000
                Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-10 06:52 +1100
                Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-09 08:00 +1100
                Re: Question about math.pi is mutable BartC <bc@freeuk.com> - 2015-11-08 22:35 +0000
                Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-09 09:54 +1100
                Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-09 13:23 +1100
                Re: Question about math.pi is mutable BartC <bc@freeuk.com> - 2015-11-09 12:22 +0000
                Re: Question about math.pi is mutable Chris Angelico <rosuav@gmail.com> - 2015-11-09 23:36 +1100
                Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-08 22:30 +1100
                Re: Question about math.pi is mutable BartC <bc@freeuk.com> - 2015-11-08 12:24 +0000
                Re: Question about math.pi is mutable Grant Edwards <invalid@invalid.invalid> - 2015-11-07 16:16 +0000
                Re: Question about math.pi is mutable Marko Rauhamaa <marko@pacujo.net> - 2015-11-07 20:00 +0200
                Re: Question about math.pi is mutable Grant Edwards <invalid@invalid.invalid> - 2015-11-08 03:31 +0000
                Re: Question about math.pi is mutable Marko Rauhamaa <marko@pacujo.net> - 2015-11-08 09:45 +0200
                Re: Question about math.pi is mutable Christian Gollwitzer <auriocus@gmx.de> - 2015-11-08 09:00 +0100
                Re: Question about math.pi is mutable Paul Rubin <no.email@nospam.invalid> - 2015-11-08 00:08 -0800
                Re: Question about math.pi is mutable Marko Rauhamaa <marko@pacujo.net> - 2015-11-08 11:49 +0200
                Re: Question about math.pi is mutable Grant Edwards <invalid@invalid.invalid> - 2015-11-09 14:49 +0000
                Re: Question about math.pi is mutable Bartc <bc@freeuk.com> - 2015-11-07 15:19 +0000
                Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-08 14:50 +1100
                Re: Question about math.pi is mutable Marko Rauhamaa <marko@pacujo.net> - 2015-11-08 11:44 +0200
                Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-08 22:11 +1100
                Re: Question about math.pi is mutable Marko Rauhamaa <marko@pacujo.net> - 2015-11-08 13:25 +0200
                Re: Question about math.pi is mutable BartC <bc@freeuk.com> - 2015-11-08 11:06 +0000
        Re: Question about math.pi is mutable Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-11-09 15:49 +0100
        Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-10 10:29 +1100
        Re: Question about math.pi is mutable Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-11-10 11:03 +0100
        Re: Question about math.pi is mutable Michael Torrie <torriem@gmail.com> - 2015-11-13 20:11 -0700
        Re: Question about math.pi is mutable Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2015-11-14 16:02 +0100
    Re: Question about math.pi is mutable Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-11-06 23:26 +0100
      Re: Question about math.pi is mutable Terry Reedy <tjreedy@udel.edu> - 2015-11-06 20:49 -0500
      Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-07 13:06 +1100
      Re: Question about math.pi is mutable Bartc <bc@freeuk.com> - 2015-11-07 23:02 +0000
        Re: Question about math.pi is mutable Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-11-07 23:27 +0000
        Re: Question about math.pi is mutable Ben Finney <ben+python@benfinney.id.au> - 2015-11-08 10:32 +1100
        Re: Question about math.pi is mutable Chris Angelico <rosuav@gmail.com> - 2015-11-08 10:52 +1100
          Re: Question about math.pi is mutable Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-11-12 21:40 +0100
            Re: Question about math.pi is mutable Steven D'Aprano <steve@pearwood.info> - 2015-11-13 09:04 +1100
              Re: Question about math.pi is mutable Denis McMahon <denismfmcmahon@gmail.com> - 2015-11-13 09:19 +0000
                Re: Question about math.pi is mutable Larry Hudson <orgnut@yahoo.com> - 2015-11-13 18:30 -0800
            Re: Question about math.pi is mutable BartC <bc@freeuk.com> - 2015-11-12 22:19 +0000
              Re: Question about math.pi is mutable Chris Angelico <rosuav@gmail.com> - 2015-11-13 09:52 +1100

csiph-web