Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.python > #48878
| Path | csiph.com!newsfeed.hal-mli.net!feeder3.hal-mli.net!newsfeed.hal-mli.net!feeder2.hal-mli.net!newsfeed.xs4all.nl!newsfeed4.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail |
|---|---|
| Return-Path | <python@mrabarnett.plus.com> |
| X-Original-To | python-list@python.org |
| Delivered-To | python-list@mail.python.org |
| X-Spam-Status | OK 0.000 |
| X-Spam-Evidence | '*H*': 1.00; '*S*': 0.00; 'python,': 0.02; 'programmer': 0.03; 'argument': 0.05; 'interpreter': 0.05; '21,': 0.07; '[1,': 0.09; 'arguments': 0.09; 'arguments,': 0.09; 'falls': 0.09; 'friday,': 0.09; 'works.': 0.09; 'python': 0.11; 'def': 0.12; 'assume': 0.14; 'thread': 0.14; '[none,': 0.16; 'challenge?': 0.16; 'cliff': 0.16; 'conclusion:': 0.16; 'confuse': 0.16; 'demonstrable': 0.16; 'docs.': 0.16; 'exception:': 0.16; 'exception?': 0.16; 'fits': 0.16; 'from:addr:mrabarnett.plus.com': 0.16; 'from:addr:python': 0.16; 'from:name:mrab': 0.16; "he'll": 0.16; 'hell.': 0.16; 'ignoring': 0.16; 'message- id:@mrabarnett.plus.com': 0.16; 'mutable': 0.16; 'object()': 0.16; 'protecting': 0.16; 'received:84.93': 0.16; 'received:84.93.230': 0.16; 'which,': 0.16; 'exception': 0.16; 'fix': 0.17; 'wrote:': 0.18; 'differ': 0.19; "python's": 0.19; '>>>': 0.22; 'example': 0.22; 'programming': 0.22; 'import': 0.22; 'header:User-Agent:1': 0.23; 'passes': 0.24; 'fine': 0.24; 'guys': 0.24; 'script': 0.25; 'posts': 0.26; 'this:': 0.26; 'pass': 0.26; 'least': 0.26; 'world,': 0.26; 'header:In-Reply-To:1': 0.27; 'function': 0.29; 'resolution': 0.29; 'raise': 0.29; 'code': 0.31; 'existence': 0.31; 'proposing': 0.31; 'anyone': 0.31; 'probably': 0.32; '(most': 0.33; 'guess': 0.33; 'could': 0.34; 'something': 0.35; 'johnson': 0.35; 'received:84': 0.35; 'version': 0.36; 'responsible': 0.36; 'should': 0.36; 'january': 0.37; 'too': 0.37; 'clear': 0.37; 'e.g.': 0.38; 'handle': 0.38; 'to:addr:python- list': 0.38; 'little': 0.38; 'recent': 0.39; 'does': 0.39; 'to:addr:python.org': 0.39; 'how': 0.40; "you're": 0.61; 'real': 0.63; 'such': 0.63; 'soon': 0.63; 'happen': 0.63; 'holding': 0.65; 'world': 0.66; 'here': 0.66; 'header:Reply-To:1': 0.67; 'reads': 0.68; 'said:': 0.68; 'default': 0.69; 'presented': 0.69; 'reply- to:no real name:2**0': 0.71; 'enjoy': 0.71; 'buddies': 0.84; 'case?': 0.84; 'examples.': 0.84; 'rage.': 0.84; 'reply- to:addr:python.org': 0.84; 'subject:Value': 0.84; 'gift': 0.85; '2013,': 0.91; 'cast': 0.91; 'rick': 0.93; '2013': 0.98 |
| X-CM-Score | 0.00 |
| X-CNFS-Analysis | v=2.1 cv=RZapVTdv c=1 sm=1 tr=0 a=0nF1XD0wxitMEM03M9B4ZQ==:117 a=0nF1XD0wxitMEM03M9B4ZQ==:17 a=0Bzu9jTXAAAA:8 a=oyR3mlnJdzkA:10 a=ihvODaAuJD4A:10 a=OUOv7kDek9cA:10 a=8nJEP1OIZ-IA:10 a=EBOSESyhAAAA:8 a=8AHkEIZyAAAA:8 a=Mpz3XJYojt8A:10 a=hSlIY0N4lP3x9z7fEQcA:9 a=wPNLvfGTeEIA:10 |
| X-AUTH | mrabarnett:2500 |
| Date | Fri, 21 Jun 2013 20:25:49 +0100 |
| From | MRAB <python@mrabarnett.plus.com> |
| User-Agent | Mozilla/5.0 (Windows NT 5.1; rv:17.0) Gecko/20130509 Thunderbird/17.0.6 |
| MIME-Version | 1.0 |
| To | python-list@python.org |
| Subject | Re: Default Value |
| References | <7e6361d5-6619-4aaa-adda-8b5f01bde57f@googlegroups.com> <b3d90d37-896c-4c80-8f94-9e046453927c@googlegroups.com> <447dd1c6-1bb2-4276-a109-78d7a067b442@d8g2000pbe.googlegroups.com> <2e92b4c7-31be-40d2-a906-ab19f3630dfa@googlegroups.com> <mailman.3627.1371742717.3114.python-list@python.org> <baf4de3c-e4ff-42c0-8d65-2f6cf825735c@googlegroups.com> <51c477dd$0$29999$c3e8da3$5496439d@news.astraweb.com> <565a1c8f-6fd9-4bab-9834-076eaea527f8@googlegroups.com> <kq23at$i39$1@dont-email.me> <7e1ed740-df18-4978-b11d-8ca9c4b5bd04@googlegroups.com> |
| In-Reply-To | <7e1ed740-df18-4978-b11d-8ca9c4b5bd04@googlegroups.com> |
| Content-Type | text/plain; charset=ISO-8859-1; format=flowed |
| Content-Transfer-Encoding | 7bit |
| X-BeenThere | python-list@python.org |
| X-Mailman-Version | 2.1.15 |
| Precedence | list |
| Reply-To | python-list@python.org |
| List-Id | General discussion list for the Python programming language <python-list.python.org> |
| List-Unsubscribe | <http://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 | <http://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe> |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.3667.1371842756.3114.python-list@python.org> (permalink) |
| Lines | 88 |
| NNTP-Posting-Host | 2001:888:2000:d::a6 |
| X-Trace | 1371842756 news.xs4all.nl 15990 [2001:888:2000:d::a6]:34208 |
| X-Complaints-To | abuse@xs4all.nl |
| Xref | csiph.com comp.lang.python:48878 |
Show key headers only | View raw
On 21/06/2013 19:26, Rick Johnson wrote:
> On Friday, June 21, 2013 12:47:56 PM UTC-5, Rotwang wrote:
>> It isn't clear to me from your posts what exactly you're
>> proposing as an alternative to the way Python's default
>> argument binding works. In your version of Python, what
>> exactly would happen when I passed a mutable argument as a
>> default value in a def statement? E.g. this:
>>
>> >>> a = [1, 2, 3]
>> >>> a.append(a)
>> >>> b = object()
>> >>> def f(x = [None, b, [a, [4]]]):
>> ... pass # do something
>>
>> What would you like to see the interpreter do in this case?
>
> Ignoring that this is a completely contrived example that has
> no use in the real world, here are one of three methods by
> which i can handle this:
>
> ============================================================
> The Benevolent Approach:
> ============================================================
> I could cast a "virtual net" over my poor lemmings before
> they jump off the cliff by throwing an exception:
>
> Traceback (most recent screw-up last):
> Line BLAH in SCRIPT
> def f(x = [None, b, [a, [4]]]):
> ArgumentError: No mutable default arguments allowed!
>
What about this:
def f(x=Foo()):
pass # do something
Should it raise an exception? Only if a Foo instance is mutable? How do
you know whether such an instance is mutable?
> ============================================================
> The Apathetic Approach:
> ============================================================
> I could just assume that a programmer is responsible for the
> code he writes. If he passes mutables into a function as
> default arguments, and then mutates the mutable later, too
> bad, he'll understand the value of writing solid code after
> a few trips to exception Hell.
>
> ============================================================
> The Malevolent Approach (disguised as beneva-loon-icy):
> ============================================================
> I could use early binding to confuse the hell out of him and
> enjoy the laughs with all my ivory tower buddies as he falls
> into fits of confusion and rage. Then enjoy again when he
> reads the docs. Ahh, the gift that just keeps on giving!
>
How does the "Apathetic Approach" differ from the "Malevolent Approach"?
> ============================================================
> Conclusion:
> ============================================================
> As you can probably guess the malevolent approach has some
> nice fringe benefits.
>
> You know, out of all these post, not one of you guys has
> presented a valid use-case that will give validity to the
> existence of this PyWart -- at least not one that CANNOT be
> reproduced by using my fine examples. All you can muster is
> some weak argument about protecting the lemmings.
>
> Is anyone up the challenge?
> Does anyone here have any real chops?
>
> PS: I won't be holding my breath.
>
Speaking of which, on 11 January 2013, in the thread "PyWart: Import
resolution order", you were asked:
"""Got any demonstrable code for Python 4000 yet?"""
and you said:
"""I am working on it. Stay tuned. Rick is going to rock your little
programming world /very/ soon."""
How soon is "/very/ soon" (clearly longer than 5 months), and how did
you fix this "PyWart"?
Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Default Value Ahmed Abdulshafy <abdulshafy@gmail.com> - 2013-06-19 12:17 -0700
Re: Default Value Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2013-06-19 22:35 +0300
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-19 12:38 -0700
Re: Default Value rusi <rustompmody@gmail.com> - 2013-06-20 05:57 -0700
Re: Default Value Roy Smith <roy@panix.com> - 2013-06-20 09:19 -0400
Re: Default Value rusi <rustompmody@gmail.com> - 2013-06-20 06:31 -0700
Re: Default Value Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-21 00:17 +0000
Re: Default Value Roy Smith <roy@panix.com> - 2013-06-20 20:25 -0400
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-20 07:49 -0700
Re: Default Value Chris Angelico <rosuav@gmail.com> - 2013-06-21 01:38 +1000
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-20 11:05 -0700
Re: Default Value Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-21 00:57 +0000
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-20 20:16 -0700
Re: Default Value Chris Angelico <rosuav@gmail.com> - 2013-06-21 17:10 +1000
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-21 07:32 -0700
Re: Default Value Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-21 16:22 +0000
Re: Default Value Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-21 15:57 +0000
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-21 10:01 -0700
Re: Default Value Rotwang <sg552@hotmail.co.uk> - 2013-06-21 18:47 +0100
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-21 11:26 -0700
Re: Default Value Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-21 18:37 +0000
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-21 12:18 -0700
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-21 12:35 -0700
Re: Default Value Chris Angelico <rosuav@gmail.com> - 2013-06-22 05:07 +1000
Re: Default Value Neil Cerutti <neilc@norwich.edu> - 2013-06-21 19:20 +0000
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-21 13:27 -0700
Re: Default Value Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-22 01:31 +0000
Re: Default Value Chris Angelico <rosuav@gmail.com> - 2013-06-22 11:40 +1000
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-21 18:42 -0700
Re: Default Value MRAB <python@mrabarnett.plus.com> - 2013-06-22 03:04 +0100
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-21 19:32 -0700
Re: Default Value MRAB <python@mrabarnett.plus.com> - 2013-06-22 20:36 +0100
Re: Default Value Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-06-22 18:51 -0400
Re: Default Value rusi <rustompmody@gmail.com> - 2013-06-21 19:43 -0700
Re: Default Value Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-06-22 09:26 +0100
Re: Default Value MRAB <python@mrabarnett.plus.com> - 2013-06-21 20:25 +0100
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-21 13:44 -0700
Re: Default Value MRAB <python@mrabarnett.plus.com> - 2013-06-21 23:49 +0100
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-21 16:51 -0700
Re: Default Value MRAB <python@mrabarnett.plus.com> - 2013-06-22 02:54 +0100
Re: Default Value Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-22 01:15 +0000
Re: Default Value Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-21 19:27 -0600
Re: Default Value rusi <rustompmody@gmail.com> - 2013-06-21 19:32 -0700
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-21 19:55 -0700
Re: Default Value rusi <rustompmody@gmail.com> - 2013-06-21 23:23 -0700
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-22 08:07 -0700
Re: Default Value rusi <rustompmody@gmail.com> - 2013-06-22 08:31 -0700
Re: Default Value rusi <rustompmody@gmail.com> - 2013-06-22 09:11 -0700
Re: Default Value Grant Edwards <invalid@invalid.invalid> - 2013-06-24 14:22 +0000
Re: [SPAM] Re: Default Value MRAB <python@mrabarnett.plus.com> - 2013-06-24 16:22 +0100
Re: Default Value Chris Angelico <rosuav@gmail.com> - 2013-06-22 11:41 +1000
Re: Default Value Michael Torrie <torriem@gmail.com> - 2013-06-21 20:46 -0600
Re: Default Value Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2013-06-22 16:40 +0200
Re: Default Value Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-06-22 12:49 -0400
Re: Default Value Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-22 12:57 -0600
Re: Default Value Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-06-22 18:48 -0400
Re: Default Value Rotwang <sg552@hotmail.co.uk> - 2013-06-22 00:40 +0100
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-21 18:15 -0700
Re: Default Value Chris Angelico <rosuav@gmail.com> - 2013-06-22 11:37 +1000
Re: Default Value Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-21 19:42 -0600
Re: Default Value Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-21 19:38 -0600
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-21 19:40 -0700
Re: Default Value Rotwang <sg552@hotmail.co.uk> - 2013-06-22 03:01 +0100
Re: Default Value Chris Angelico <rosuav@gmail.com> - 2013-06-22 12:18 +1000
Re: Default Value Rotwang <sg552@hotmail.co.uk> - 2013-06-22 03:25 +0100
Re: Default Value Rotwang <sg552@hotmail.co.uk> - 2013-06-22 18:19 +0100
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-22 11:49 -0700
Re: Default Value Rotwang <sg552@hotmail.co.uk> - 2013-06-23 01:49 +0100
Re: Default Value rusi <rustompmody@gmail.com> - 2013-06-20 10:12 -0700
Re: Default Value Chris Angelico <rosuav@gmail.com> - 2013-06-21 03:19 +1000
Re: Default Value rusi <rustompmody@gmail.com> - 2013-06-20 10:30 -0700
Re: Default Value Ian Kelly <ian.g.kelly@gmail.com> - 2013-06-20 11:57 -0600
Re: Default Value rusi <rustompmody@gmail.com> - 2013-06-20 11:15 -0700
Re: Default Value Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-21 01:08 +0000
Re: Default Value Tim Chase <python.list@tim.thechases.com> - 2013-06-20 20:26 -0500
Re: Default Value Roy Smith <roy@panix.com> - 2013-06-20 21:40 -0400
Re: Default Value Tim Chase <python.list@tim.thechases.com> - 2013-06-20 21:02 -0500
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-20 11:07 -0700
Re: Default Value alex23 <wuwei23@gmail.com> - 2013-06-21 10:55 +1000
Re: Default Value 88888 Dihedral <dihedral88888@gmail.com> - 2013-06-20 19:18 -0700
Re: Default Value Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-21 02:26 +0000
Re: Default Value "Lefavor, Matthew (GSFC-582.0)[MICROTEL LLC]" <matthew.lefavor@nasa.gov> - 2013-06-20 17:28 -0500
Re: Default Value Rick Johnson <rantingrickjohnson@gmail.com> - 2013-06-21 08:17 -0700
Re: Default Value Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-21 01:28 +0000
Re: Default Value Gary Herron <gherron@digipen.edu> - 2013-06-19 12:57 -0700
Re: Default Value Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-20 01:17 +0000
csiph-web