Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.python > #75665
| Path | csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!backfill.erje.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.xs4all.nl!newsfeed4a.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail |
|---|---|
| Return-Path | <ian.g.kelly@gmail.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; 'else:': 0.03; 'syntax': 0.04; 'elif': 0.05; 'class,': 0.07; 'method.': 0.07; 'callback': 0.09; 'classes.': 0.09; 'constructor': 0.09; 'data:': 0.09; 'front,': 0.09; 'function,': 0.09; 'method,': 0.09; 'url:blog': 0.10; 'python': 0.11; 'def': 0.12; 'mostly': 0.14; 'command)': 0.16; 'data)': 0.16; 'function;': 0.16; 'lambda': 0.16; 'lambda:': 0.16; 'limited)': 0.16; 'mine.': 0.16; 'specifying': 0.16; 'subject:object': 0.16; 'subject:simple': 0.16; 'subject:type': 0.16; 'java,': 0.16; 'language': 0.16; 'wrote:': 0.18; 'command': 0.22; '>>>': 0.22; 'aug': 0.22; "aren't": 0.24; 'class.': 0.26; 'this:': 0.26; 'header:In-Reply- To:1': 0.27; 'point': 0.28; 'function': 0.29; 'raise': 0.29; 'message-id:@mail.gmail.com': 0.30; "i'm": 0.30; 'anonymous': 0.31; "d'aprano": 0.31; 'skip:q 20': 0.31; 'steven': 0.31; 'class': 0.32; 'probably': 0.32; 'front': 0.32; 'interface': 0.32; 'implemented': 0.33; 'totally': 0.33; 'used,': 0.33; 'third': 0.33; 'actual': 0.34; 'skip:_ 10': 0.34; 'could': 0.34; 'classes': 0.35; 'case,': 0.35; 'received:google.com': 0.35; 'really': 0.36; 'scheme': 0.36; 'done': 0.36; 'url:org': 0.36; 'experience,': 0.37; 'project': 0.37; 'easily': 0.37; 'being': 0.38; 'implement': 0.38; 'to:addr:python-list': 0.38; 'pm,': 0.38; 'subject:" ': 0.39; 'to:addr:python.org': 0.39; 'enough': 0.39; 'back': 0.62; 'name': 0.63; 'url:p': 0.64; 'provide': 0.64; 'more': 0.64; 'linked': 0.65; 'talking': 0.65; 'here': 0.66; 'to,': 0.72; 'as:': 0.81; 'localized': 0.84; 'object:': 0.84; 'write:': 0.91 |
| DKIM-Signature | v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type; bh=nM2/PDdSLUzmyGNiRgOu63nl0lXRq+ImUq/ZEWjNh8w=; b=vLCRZtJGdjetTpM0pmh9t+9/ESNlUL0bdkSIezpX1Y6FwEWPlK+8YOuaQ5VJ8GccGs pu16yojcPzfvuYL9ql9PEjk2aaIPT+ZpIKYYXWnhyueBOTUTJA+md6SSmAex4C+Y76iB r0EEgxB3KV+Nr3cEZB6Db+0VH9spc/JkBuIg/JdZei2v/EhCv0ouS/rSRH2cjyhjOgLT jisGuZbBqnCCS2vMEXs9K7xWh3gVDASe2FY7b5HQg+eg/XHm+HRgFdeQnhw9pgPavSPz /yj9noZtP3roYW3voF36VweWZrX5Jg7yDR95kwJFXg8BHh5ld2yxswZmdS0ZXOPEu5b0 5oQQ== |
| X-Received | by 10.70.128.137 with SMTP id no9mr278833pdb.143.1407134533962; Sun, 03 Aug 2014 23:42:13 -0700 (PDT) |
| MIME-Version | 1.0 |
| In-Reply-To | <8738dclslo.fsf@elektro.pacujo.net> |
| References | <7ef67ccc-3fc3-47dd-b858-09ef3b57a497@googlegroups.com> <87r40zmkhr.fsf@elektro.pacujo.net> <53dd0717$0$29973$c3e8da3$5496439d@news.astraweb.com> <mailman.12548.1407009552.18130.python-list@python.org> <70e5f2f1-661f-40f2-bb7a-76e569c4d092@googlegroups.com> <CALwzidmZMReJL-XqOuxj5Q7mQhVA29itGZdmGCT3-6B7eyO_Sg@mail.gmail.com> <lrk7li$6nb$1@ger.gmane.org> <1407057464.64980.YahooMailNeo@web163806.mail.gq1.yahoo.com> <lrkvs1$6hk$1@ger.gmane.org> <1407063072.46317.YahooMailNeo@web163803.mail.gq1.yahoo.com> <mailman.12578.1407065042.18130.python-list@python.org> <87wqaplj8h.fsf@elektro.pacujo.net> <53ded02e$0$29980$c3e8da3$5496439d@news.astraweb.com> <8738dclslo.fsf@elektro.pacujo.net> |
| From | Ian Kelly <ian.g.kelly@gmail.com> |
| Date | Mon, 4 Aug 2014 00:41:32 -0600 |
| Subject | Re: Correct type for a simple "bag of attributes" namespace object |
| To | Python <python-list@python.org> |
| Content-Type | text/plain; charset=UTF-8 |
| X-BeenThere | python-list@python.org |
| X-Mailman-Version | 2.1.15 |
| 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> |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.12622.1407134543.18130.python-list@python.org> (permalink) |
| Lines | 99 |
| NNTP-Posting-Host | 2001:888:2000:d::a6 |
| X-Trace | 1407134543 news.xs4all.nl 2942 [2001:888:2000:d::a6]:49016 |
| X-Complaints-To | abuse@xs4all.nl |
| Xref | csiph.com comp.lang.python:75665 |
Show key headers only | View raw
On Sun, Aug 3, 2014 at 11:41 PM, Marko Rauhamaa <marko@pacujo.net> wrote:
> Steven D'Aprano <steve+comp.lang.python@pearwood.info>:
> And I'm talking about a third kind: object-based. It is in active
> (albeit limited) use in scheme: <URL: http://irreal.org/blog/?p=40>. I'm
> currently using the principle in a project of mine.
>
> In Java, you use anonymous classes for the same thing. In Python, you
> can think of the principle as one-time classes. So instead of writing:
In my experience, 99% of the time when anonymous classes are used,
they only contain one method. That's because they're not really being
used to implement some interface abstractly; they mostly exist to
provide a means of specifying a callback function in a language where
functions aren't first-class.
>
> class A:
> def __init__(self, x, y, z):
> self.x = x
> self.d = y * y + z * z
>
> def f(self):
> return self.x - self.d
>
> you write:
>
> def A(x, y, z):
> d = y * y + z * z
>
> class Anonymous:
> def f(self):
> return x - d
>
> return Anonymous()
And it's the same thing here. This isn't an interface. It's a
function, so just return a function and be done with it. And in the
rare event that you actually mean to implement more than one method,
then you have enough functionality localized that it's probably
worthwhile to just name it and make it an actual class.
> Now, if you always did this, you would notice that classes are
> unnecessary clutter and would call for syntax like this:
>
> def A(x, y, z):
> d = y * y + z * z
> return object:
> def f():
> return x - d
The presence of "object" here feels totally unnecessary to me. If the
point is to avoid having a class, then why create a class? In this
case you could easily just return a function. To take a more complex
case, say the Scheme make-queue constructor that you linked to, you
could still just return a function; the same could be implemented in
Python 3 as:
def make_queue():
front = []
back = []
def queue_command(command, data=None):
def exchange():
nonlocal front, back
front = back; front.reverse()
back = []
if command == 'push':
back.append(data)
elif command == 'pop':
if not front: exchange()
return front.pop()
elif command == 'peek':
if not front: exchange()
return front[-1]
elif command == 'show':
return str(list(reversed(front)) + back)
else:
raise ValueError('Illegal command to queue object ' + command)
queue_command.push = lambda data: queue_command('push', data)
queue_command.pop = lambda: queue_command('pop')
queue_command.peek = lambda: queue_command('peek')
return queue_command
>>> queue = make_queue()
>>> queue.push(1)
>>> queue.push(2)
>>> queue.pop()
1
>>> queue.push(3)
>>> queue.push(4)
>>> queue.pop()
2
>>> queue.peek()
3
>>> queue.pop()
3
>>> queue.pop()
4
Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
3 Suggestions to Make Python Easier For Children Mark Summerfield <list@qtrac.plus.com> - 2014-08-01 23:45 -0700
Re: 3 Suggestions to Make Python Easier For Children Marko Rauhamaa <marko@pacujo.net> - 2014-08-02 10:14 +0300
Re: 3 Suggestions to Make Python Easier For Children Mark Summerfield <list@qtrac.plus.com> - 2014-08-02 00:38 -0700
Re: 3 Suggestions to Make Python Easier For Children Marko Rauhamaa <marko@pacujo.net> - 2014-08-02 11:03 +0300
Re: 3 Suggestions to Make Python Easier For Children Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-03 02:00 +1000
Re: 3 Suggestions to Make Python Easier For Children Marko Rauhamaa <marko@pacujo.net> - 2014-08-02 20:07 +0300
Re: 3 Suggestions to Make Python Easier For Children Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-08-02 18:29 +0100
Re: 3 Suggestions to Make Python Easier For Children Marko Rauhamaa <marko@pacujo.net> - 2014-08-02 21:33 +0300
Re: 3 Suggestions to Make Python Easier For Children Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-03 01:43 +1000
Correct type for a simple “bag of attributes” namespace object (was: 3 Suggestions to Make Python Easier For Children) Ben Finney <ben+python@benfinney.id.au> - 2014-08-03 05:58 +1000
Re: Correct type for a simple "bag of attributes" namespace object (was: 3 Suggestions to Make Python Easier For Children) Mark Summerfield <list@qtrac.plus.com> - 2014-08-02 13:46 -0700
Re: Correct type for a simple "bag of attributes" namespace object (was: 3 Suggestions to Make Python Easier For Children) Chris Angelico <rosuav@gmail.com> - 2014-08-03 07:05 +1000
Re: Correct type for a simple "bag of attributes" namespace object Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-08-02 22:16 +0100
Re: Correct type for a simple "bag of attributes" namespace object Chris Angelico <rosuav@gmail.com> - 2014-08-03 07:24 +1000
Re: Correct type for a simple "bag of attributes" namespace object Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-08-02 22:23 +0100
Re: Correct type for a simple "bag of attributes" namespace object (was: 3 Suggestions to Make Python Easier For Children) Devin Jeanpierre <jeanpierreda@gmail.com> - 2014-08-02 16:18 -0700
Re: Correct type for a simple "bag of attributes" namespace object (was: 3 Suggestions to Make Python Easier For Children) Chris Angelico <rosuav@gmail.com> - 2014-08-03 09:27 +1000
Re: Correct type for a simple "bag of attributes" namespace object (was: 3 Suggestions to Make Python Easier For Children) Ian Kelly <ian.g.kelly@gmail.com> - 2014-08-02 18:59 -0600
Re: Correct type for a simple "bag of attributes" namespace object Terry Reedy <tjreedy@udel.edu> - 2014-08-02 22:40 -0400
Re: Correct type for a simple "bag of attributes" namespace object Terry Reedy <tjreedy@udel.edu> - 2014-08-02 22:43 -0400
Re: Correct type for a simple "bag of attributes" namespace object Albert-Jan Roskam <fomcl@yahoo.com> - 2014-08-03 02:17 -0700
Re: Correct type for a simple "bag of attributes" namespace object Peter Otten <__peter__@web.de> - 2014-08-03 11:37 +0200
Re: Correct type for a simple "bag of attributes" namespace object Albert-Jan Roskam <fomcl@yahoo.com> - 2014-08-03 03:51 -0700
Re: Correct type for a simple "bag of attributes" namespace object Albert-Jan Roskam <fomcl@yahoo.com> - 2014-08-03 04:14 -0700
Re: Correct type for a simple "bag of attributes" namespace object Peter Otten <__peter__@web.de> - 2014-08-03 13:23 +0200
Re: Correct type for a simple "bag of attributes" namespace object Marko Rauhamaa <marko@pacujo.net> - 2014-08-03 17:51 +0300
Re: Correct type for a simple "bag of attributes" namespace object Roy Smith <roy@panix.com> - 2014-08-03 11:09 -0400
Re: Correct type for a simple "bag of attributes" namespace object Marko Rauhamaa <marko@pacujo.net> - 2014-08-03 18:52 +0300
Re: Correct type for a simple "bag of attributes" namespace object Terry Reedy <tjreedy@udel.edu> - 2014-08-03 18:55 -0400
Re: Correct type for a simple "bag of attributes" namespace object Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-04 11:19 +1000
Re: Correct type for a simple "bag of attributes" namespace object Terry Reedy <tjreedy@udel.edu> - 2014-08-04 01:26 -0400
Re: Correct type for a simple "bag of attributes" namespace object Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-04 10:13 +1000
Re: Correct type for a simple "bag of attributes" namespace object Roy Smith <roy@panix.com> - 2014-08-03 20:59 -0400
Re: Correct type for a simple "bag of attributes" namespace object Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-08-04 13:00 +1200
Re: Correct type for a simple "bag of attributes" namespace object Marko Rauhamaa <marko@pacujo.net> - 2014-08-04 08:41 +0300
Re: Correct type for a simple "bag of attributes" namespace object Ian Kelly <ian.g.kelly@gmail.com> - 2014-08-04 00:41 -0600
Re: Correct type for a simple "bag of attributes" namespace object Marko Rauhamaa <marko@pacujo.net> - 2014-08-04 09:57 +0300
Re: Correct type for a simple "bag of attributes" namespace object Akira Li <4kir4.1i@gmail.com> - 2014-08-03 18:22 +0400
Re: Correct type for a simple “bag of attributes” namespace object Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-08-03 13:28 +0100
Re: Correct type for a simple “bag of attributes” namespace object Roy Smith <roy@panix.com> - 2014-08-03 08:40 -0400
Re: Correct type for a simple “bag of attributes” namespace object Chris Angelico <rosuav@gmail.com> - 2014-08-03 22:56 +1000
Re: Correct type for a simple “bag of attributes” namespace object Roy Smith <roy@panix.com> - 2014-08-03 09:25 -0400
Re: Correct type for a simple “bag of attributes” namespace object Chris Angelico <rosuav@gmail.com> - 2014-08-03 23:35 +1000
Re: Correct type for a simple “bag of attributes” namespace object Roy Smith <roy@panix.com> - 2014-08-03 10:36 -0400
Re: Correct type for a simple “bag of attributes” namespace object Chris Angelico <rosuav@gmail.com> - 2014-08-04 01:00 +1000
Re: Correct type for a simple “bag of attributes” namespace object Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-08-03 18:38 +0100
Re: Correct type for a simple “bag of attributes” namespace object Roy Smith <roy@panix.com> - 2014-08-03 13:44 -0400
Re: 3 Suggestions to Make Python Easier For Children Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-08-02 08:46 +0100
Re: 3 Suggestions to Make Python Easier For Children Mark Summerfield <list@qtrac.plus.com> - 2014-08-02 01:03 -0700
Re: 3 Suggestions to Make Python Easier For Children Terry Reedy <tjreedy@udel.edu> - 2014-08-02 19:14 -0400
Re: 3 Suggestions to Make Python Easier For Children Terry Reedy <tjreedy@udel.edu> - 2014-08-02 19:12 -0400
Re: 3 Suggestions to Make Python Easier For Children Brian Blais <bblais@gmail.com> - 2014-08-05 07:36 -0400
Re: 3 Suggestions to Make Python Easier For Children Marko Rauhamaa <marko@pacujo.net> - 2014-08-05 15:04 +0300
Re: 3 Suggestions to Make Python Easier For Children Skip Montanaro <skip@pobox.com> - 2014-08-05 07:31 -0500
Re: 3 Suggestions to Make Python Easier For Children Marko Rauhamaa <marko@pacujo.net> - 2014-08-05 16:19 +0300
Re: 3 Suggestions to Make Python Easier For Children MRAB <python@mrabarnett.plus.com> - 2014-08-05 15:11 +0100
Re: 3 Suggestions to Make Python Easier For Children Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-06 02:14 +1000
Re: 3 Suggestions to Make Python Easier For Children Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-08-05 22:43 +1000
Re: 3 Suggestions to Make Python Easier For Children Chris Angelico <rosuav@gmail.com> - 2014-08-05 23:08 +1000
Re: 3 Suggestions to Make Python Easier For Children Chris Angelico <rosuav@gmail.com> - 2014-08-05 23:00 +1000
csiph-web