Re: "eval vs operator.methodcaller" - which is better?

Path	csiph.com!usenet.pasdenom.info!news.albasani.net!newsfeed.freenet.ag!news2.euro.net!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path	<rosuav@gmail.com>
X-Original-To	python-list@python.org
Delivered-To	python-list@mail.python.org
X-Spam-Status	OK 0.005
X-Spam-Evidence	'H': 0.99; 'S': 0.00; 'operator': 0.03; 'function,': 0.07; 'raises': 0.07; 'python': 0.09; '(the': 0.15; '24,': 0.16; '33,': 0.16; '42,': 0.16; 'from:addr:rosuav': 0.16; 'from:name:chris angelico': 0.16; 'operators.': 0.16; 'subject:which': 0.16; 'wrote:': 0.17; '>>>': 0.18; 'module': 0.19; 'versions': 0.20; 'specifically': 0.24; 'header:In-Reply- To:1': 0.25; 'am,': 0.27; 'question': 0.27; 'mind.': 0.27; 'message-id:@mail.gmail.com': 0.27; 'smart': 0.29; 'generally': 0.32; 'to:addr:python-list': 0.33; 'another': 0.33; 'received:google.com': 0.34; 'done': 0.34; 'needed': 0.35; 'subject:?': 0.35; 'received:209.85': 0.35; 'but': 0.36; 'functional': 0.36; 'thank': 0.36; 'received:209': 0.37; 'skip:l 20': 0.38; 'skip:o 20': 0.38; 'to:addr:python.org': 0.39; 'most': 0.61; 'you.': 0.61; 'unnecessary': 0.65; '2013': 0.84; 'subject:better': 0.84
DKIM-Signature	v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:content-type; bh=w4OcR0+dtGbJ6xPQDN4GB4O+t6PspWMxuwPfnPGbL2Y=; b=ZM9woWkKwfTd/TYiJun+gmi9rcCKXkuuMK69EP2t8HOxHqhp6d+UB0cZVLim0+pQYj ErOywnd3w/HuLDDJIpTzD6B5MfZCb4Fl3Uh938CozJR7uKwL2UKbPCwlzF5dP8a4jeFH 9tDxBwVOwM0zT9jQRHef5yJ1oVqPJysOdOprWJ/XMwFe4xg289Qp+YDwlv59KUS4DPka wk51K/LgWC88z9HoHyMVWJkKTJMxM58m5cAG9tfZaqk+ZrjkfPX53TQwCpL0ZP2Kixjy 22ojFwjNbf9Oc9CjKNs6FF9wpnlsIFs27dtvdvsurxdhF+BxJFDLkrQiYRbA+6ebGPCq E4+Q==
MIME-Version	1.0
X-Received	by 10.52.67.164 with SMTP id o4mr16906406vdt.42.1363615383539; Mon, 18 Mar 2013 07:03:03 -0700 (PDT)
In-Reply-To	<CAFtnWG99JCUEvfhMFTMo5=bSbRw3Y80yqZH-as0RRCUUcSGiJQ@mail.gmail.com>
References	<CAFtnWG-8dndo6KYrmKvgsbiB5YkfBOgbPLrzHXauuOygvGbHtw@mail.gmail.com> <CAPTjJmpDpqKfwx056VmR8umpX5aUPZsxNTVzGmXUkW_P_-ttYQ@mail.gmail.com> <CAFtnWG99JCUEvfhMFTMo5=bSbRw3Y80yqZH-as0RRCUUcSGiJQ@mail.gmail.com>
Date	Tue, 19 Mar 2013 01:03:03 +1100
Subject	Re: "eval vs operator.methodcaller" - which is better?
From	Chris Angelico <rosuav@gmail.com>
To	python-list@python.org
Content-Type	text/plain; charset=ISO-8859-1
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.3448.1363615385.2939.python-list@python.org> (permalink)
Lines	20
NNTP-Posting-Host	2001:888:2000:d::a6
X-Trace	1363615385 news.xs4all.nl 6961 [2001:888:2000:d::a6]:45818
X-Complaints-To	abuse@xs4all.nl
Xref	csiph.com comp.lang.python:41418

Show key headers only | View raw

On Tue, Mar 19, 2013 at 12:58 AM, Laxmikant Chitare
<laxmikant.general@gmail.com> wrote:
> Aha, that was smart Chris. Thank you.
>
> But this raises another question in my mind. What is the use case for
> operator.methodcaller ?

Most of the operator module is functional versions of what can be done
elsewhere with operators. They're not generally needed unless you
specifically need a function, such as for a map() call:

>>> a=[1,2,3,4,5]
>>> b=[50,40,30,20,10]
>>> list(map(operator.add,a,b))
[51, 42, 33, 24, 15]

(The list() call is unnecessary in Python 2, but means this will also
work in Python 3.)

ChrisA

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

Thread

Re: "eval vs operator.methodcaller" - which is better? Chris Angelico <rosuav@gmail.com> - 2013-03-19 01:03 +1100

csiph-web