Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!news.mixmin.net!weretis.net!feeder4.news.weretis.net!ecngs!feeder2.ecngs.de!newsfeed.freenet.ag!news2.euro.net!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path: <chris@rebertia.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; 'modify': 0.05; 'skip:` 10': 0.05; 'defines': 0.07; 'executed': 0.07; 'wrapped': 0.07; 'received:mail-vb0-f46.google.com': 0.09; 'subject:()': 0.09; 'cc:addr:python-list': 0.10; 'def': 0.10; '[2,': 0.16; 'class;': 0.16; 'in-place': 0.16; 'oct': 0.16; 'shell:': 0.16; 'subject:array': 0.16; 'mon,': 0.16; 'wrote:': 0.17; 'skip:` 20': 0.17; 'received:209.85.212.46': 0.18; 'skip:_ 20': 0.22; 'cc:2**0': 0.23; 'class.': 0.23; 'needed.': 0.23; 'cc:no real name:2**0': 0.24; 'cc:addr:python.org': 0.25; 'header:In-Reply- To:1': 0.25; 'am,': 0.27; 'plain': 0.27; 'andrew': 0.27; 'message- id:@mail.gmail.com': 0.27; "doesn't": 0.28; 'received:209.85.212': 0.28; 'all.': 0.28; 'chris': 0.28; '>>>>': 0.29; 'wrap': 0.29; 'class': 0.29; 'lists': 0.31; 'code': 0.31; 'print': 0.32; 'received:google.com': 0.34; 'lists.': 0.35; 'expected': 0.35; 'pm,': 0.35; 'received:209.85': 0.35; 'test': 0.36; 'october': 0.37; 'item': 0.37; 'received:209': 0.37; 'subject:: ': 0.38; 'header:Received:5': 0.40; 'your': 0.60; 'behavior': 0.64; 'sender:addr:chris': 0.84; '\xe2\x80\xa6': 0.84
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rebertia.com; s=google; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; bh=7j5q/n8SS+b7Km2NSLHaqhhDzrFS1CPV0ModdFTTX24=; b=JX4O4s6Lv7SxtbhVAqejgEyPAQNBmReiMucj5PDWpuBzORzR3j2wBe6uSm9QKSBCFJ A+BctQuO0g7A2uXxu14iqBdR6mCDF1BNhtfyrlLm6rJGZZOCuEit0sGYK9Wqr+9CZYUx xl365L79wCqmOho8posRBYdpQKMaakbr2jjrI=
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding:x-gm-message-state; bh=7j5q/n8SS+b7Km2NSLHaqhhDzrFS1CPV0ModdFTTX24=; b=ePpL29pJEMIoYBcfrV/j7akSr7vX6GpArAdSXV4G+TBo8X+si6Q8izIijZ+OywweRA 8STemPqsaSdg7wvMF8wKoNnH9HaILgpRoVU1vdXmoWrDIP3YHMZV4i/cYIECLI9yHDCy 3UCD+hmJsi65pJ8UbXxjSPT+GYQaPyRgCa7/10QF9K2N61sgdSHnwzvUMnNl5x9URBaA jRtzzA6v7Spk/AlbD+1AnTW6Oa2igaPj9NdcxcexFnYapNjvmBZOVUmilSI5TCWh4NF8 8n/xDb2TLgNL2CIzrvGsD4nyj4aZqmkI4UHDMSqAfVYti2qAk1k9TN6weT+nN99C/MyS HKqQ==
MIME-Version: 1.0
Sender: chris@rebertia.com
In-Reply-To: <b50501de-b204-4e47-b907-0a249281b3d1@googlegroups.com>
References: <6998a955-7b34-4f4f-b8d6-62d1028f7561@googlegroups.com> <mailman.2986.1351482209.27098.python-list@python.org> <bb922c4b-08b5-4e93-9452-5306b2d953a9@googlegroups.com> <0215c39b-47f3-46c5-9173-598f0136a881@g7g2000pbi.googlegroups.com> <b50501de-b204-4e47-b907-0a249281b3d1@googlegroups.com>
Date: Mon, 29 Oct 2012 01:37:47 -0700
X-Google-Sender-Auth: skyDZnyyOSxzRZW4cbq1AikFJrI
Subject: Re: Negative array indicies and slice()
From: Chris Rebert <clp2@rebertia.com>
To: andrewr3mail@gmail.com
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
X-Gm-Message-State: ALoCoQkM7XG7l16uFPi/s+NPkOIklw/vCQwsDSN1s+TE2d3gdzoDvmkNdPYIyG7OOrZDuGQwgdm0
Cc: python-list@python.org
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: <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.2999.1351499869.27098.python-list@python.org>
Lines: 38
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1351499869 news.xs4all.nl 6942 [2001:888:2000:d::a6]:41632
X-Complaints-To: abuse@xs4all.nl
Xref: csiph.com comp.lang.python:32351

On Mon, Oct 29, 2012 at 1:24 AM,  <andrewr3mail@gmail.com> wrote:
> On Sunday, October 28, 2012 9:44:56 PM UTC-7, alex23 wrote:
>> On Oct 29, 2:09 pm, Andrew <andrewr3m...@gmail.com> wrote:
<snip>
>>     class RangedSlicer(list):
<snip>
>> Then wrap your lists with your RangedSlicer class as needed.
>
> Hmmm...
>
> I began a test in an interactive shell:
>>>> class RangedSlicer(list):
> ...     def __getitem__(self,item):
> ...             print item
> =E2=80=A6

This just defines a class; it doesn't modify in-place the normal
behavior of plain lists. You have to actually *use* the class.

>>>> a=3D[1,2,3,4,5]

You never wrapped `a` in a RangedSlicer or otherwise made use of RangedSlic=
er!
You wanted:
a =3D RangedSlicer([1,2,3,4,5])

>>>> a.__getitem__( slice(1,5) )
> [2, 3, 4, 5]
>
> Very odd...  I would have expected [1,2,3,4]

"[2, 3, 4, 5]" is the return value from `a.__getitem__( slice(1,5) )`
(or, equivalently, from `[1,2,3,4,5][1:5]`). It is not the result of
"print item"; that line of code is never executed since you never used
the RangedSlicer class at all.

Regards,
Chris