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: <andrea.crotti.0@gmail.com>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
X-Spam-Status: OK 0.002
X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; '*args,': 0.07; 'overflow': 0.07; '**kwargs)': 0.09; '**kwargs):': 0.09; 'received:mail- lpp01m010-f46.google.com': 0.09; 'cc:addr:python-list': 0.10; 'def': 0.10; 'subject:not': 0.11; 'stack': 0.15; 'cache:': 0.16; 'decorators': 0.22; 'example': 0.23; 'this:': 0.23; 'cc:no real name:2**0': 0.24; 'second': 0.24; 'cc:2**1': 0.24; 'cc:addr:python.org': 0.25; 'header:In-Reply-To:1': 0.25; 'looks': 0.26; 'message-id:@mail.gmail.com': 0.27; 'skip:_ 10': 0.29; 'received:209.85.215.46': 0.30; 'received:google.com': 0.34; 'received:209.85': 0.35; 'but': 0.36; 'received:209': 0.37; 'subject:: ': 0.38; 'header:Received:5': 0.40; 'think': 0.40; 'first': 0.61; 'fibonacci': 0.91
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=+p7e13wCF/doEuoeBdHmsZXTzb08AS4J/KAZysEwRqA=; b=ql0Z6FAYSjYFMMX47DwYZe7YfSL34m5MtwpcK3ZN1stz0hT9uqs/csttTib7PzurtE iNpOhvRnCsfzaySoDsWK95pzmSvhs54V6xPZ0MNMDzYBfhXhVeq8A8fRHFx6cxhj4zGs 2zhHlfGXrF4fqxYv3ubuvHLv9mNpdKgtVJOWoYfgYV9BNbE5wtCx/w0UX1CBXatIc/+e Wrkoyz/cvDYNB2jQwRt4EvbwWnT2Bin3sDpgznfcVLgQo14SBoQiI0valVXLphTsGwfe zwKUiA7+WSgbH2iTulxKucWsUn+cD/8DgOFwXqYZJAfKd9NIB5Dy5l1ohojO38GDTWLf iESg==
MIME-Version: 1.0
In-Reply-To: <1017333532.1009581.1347628946603.JavaMail.root@sequans.com>
References: <XnsA0CE7D6F43F18duncanbooth@127.0.0.1> <1017333532.1009581.1347628946603.JavaMail.root@sequans.com>
Date: Fri, 14 Sep 2012 15:12:26 +0100
Subject: Re: Decorators not worth the effort
From: andrea crotti <andrea.crotti.0@gmail.com>
To: Jean-Michel Pichavant <jeanmichel@sequans.com>
Content-Type: text/plain; charset=ISO-8859-1
Cc: python-list@python.org, duncan booth <duncan.booth@suttoncourtenay.org.uk>
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.704.1347631954.27098.python-list@python.org>
Lines: 28
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1347631954 news.xs4all.nl 6940 [2001:888:2000:d::a6]:40994
X-Complaints-To: abuse@xs4all.nl
Xref: csiph.com comp.lang.python:29167

I think one very nice and simple example of how decorators can be used is this:

def memoize(f, cache={}, *args, **kwargs):
    def _memoize(*args, **kwargs):
        key = (args, str(kwargs))
        if not key in cache:
            cache[key] = f(*args, **kwargs)

        return cache[key]

    return _memoize

def fib(n):
    if n <= 1:
        return 1
    return fib(n-1) + fib(n-2)

@memoize
def fib_memoized(n):
    if n <= 1:
        return 1
    return fib_memoized(n-1) + fib_memoized(n-2)


The second fibonacci looks exactly the same but while the first is
very slow and would generate a stack overflow the second doesn't..

I might use this example for the presentation, before explaining what it is..