Path: csiph.com!usenet.pasdenom.info!aioe.org!news.stack.nl!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!post.news.xs4all.nl!not-for-mail
Return-Path: <jeanpierreda@gmail.com>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
X-Spam-Status: OK 0.007
X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'python,': 0.02; 'sfxlen:2': 0.11; 'cc:addr:python-list': 0.15; '"define",': 0.16; '"right"': 0.16; 'mathematics.': 0.16; 'reasonable.': 0.16; 'so.': 0.16; 'language': 0.17; 'operator': 0.18; 'def': 0.20; 'programming': 0.21; 'wrote:': 0.21; 'pascal': 0.22; 'stands': 0.22; 'header:In-Reply-To:1': 0.22; 'cc:no real name:2**0': 0.26; 'defined': 0.27; 'message-id:@mail.gmail.com': 0.27; 'cc:addr:python.org': 0.27; '25,': 0.29; 'assignment': 0.29; 'closer': 0.29; 'tim': 0.29; 'cc:2**0': 0.31; 'received:209.85': 0.32; 'received:google.com': 0.32; 'mathematical': 0.33; 'received:209.85.214': 0.35; 'received:209': 0.35; 'actually': 0.35; 'but': 0.36; 'common': 0.38; 'mar': 0.61; 'fact,': 0.63; '2012': 0.69; 'verb,': 0.84
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 :cc:content-type; bh=MWaaFcWLrHu7tGliO30SuP+xFNTezaWdn89ZwjTXVxY=; b=h3uyLLoMB5Nd9ymJHcK3hF92sVp9zqhM0B2N/H734xe+KYa8zlZRs1r6ZeCy0veNxW +yRV5rBui74W701unfj4yi1yLs8vtsVFEZO27BgDVknuCULQYrMrGViPVI5yrDr1LNSZ hMtQkjaD1RFyS5gAVzPcIQA2QUvwHbp+DCvm5PEvdocPsPCsIeXdvJeree+kCBM7JQGH ExqypuGvnovLnvjC5YHlSfgsF5Za8xCc48lmbhsxSjtqekwz2H3qM/4SohS9GmNP3lHg E1aPA8SPydg4jGku4hDYkAjU+r6VHwRM36PLLOWe3rJmCi3Xyb7iQtblKTt2whMiHhL3 IBug==
MIME-Version: 1.0
In-Reply-To: <4f6f36bf$0$1390$4fafbaef@reader2.news.tin.it>
References: <4f6d0060$0$6634$9b4e6d93@newsspool2.arcor-online.net> <mailman.948.1332551363.3037.python-list@python.org> <4f6f0d24$0$6561$9b4e6d93@newsspool4.arcor-online.net> <4F6F1792.1060709@tim.thechases.com> <CAPTjJmpnYxZkLGQ4Tksw-2aaG5KAgPwoUe0EP8_OW8MdsijPdA@mail.gmail.com> <mailman.968.1332683287.3037.python-list@python.org> <4f6f36bf$0$1390$4fafbaef@reader2.news.tin.it>
From: Devin Jeanpierre <jeanpierreda@gmail.com>
Date: Mon, 26 Mar 2012 04:52:13 -0400
Subject: Re: Documentation, assignment in expression.
To: Kiuhnm <kiuhnm03.4t.yahoo.it@mail.python.org>
Content-Type: text/plain; charset=UTF-8
Cc: python-list@python.org
X-BeenThere: python-list@python.org
X-Mailman-Version: 2.1.12
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.985.1332751983.3037.python-list@python.org>
Lines: 31
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1332751983 news.xs4all.nl 6860 [2001:888:2000:d::a6]:34940
X-Complaints-To: abuse@xs4all.nl
Xref: csiph.com comp.lang.python:22164

On Sun, Mar 25, 2012 at 11:16 AM, Kiuhnm
<kiuhnm03.4t.yahoo.it@mail.python.org> wrote:
> On 3/25/2012 15:48, Tim Chase wrote:
>>
>> The old curmudgeon in me likes the Pascal method of using "=" for
>> equality-testing, and ":=" for assignment which feels a little closer to
>> mathematical use of "=".
>
>
> Unfortunately, ":=" means "is defined as" in mathematics. The "right"
> operator would have been "<-".


"Is defined as" is actually pretty reasonable. "Define this to be
that" is a common way to speak about assignment. Its only difference
is the present tense. For example, in Python, "def" stands for
"define", but we can overwrite previous definitions::

    def f(x): return x
    def f(x): return 2
    f(3) == 2

In fact, in pretty every programming language that I know of with a
"define" assignment verb, this is so. For example, in Scheme, x is 2
at the end::

    (define x 1)
    (define x 2)
    x

-- Devin