Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder1.news.weretis.net!feeder.erje.net!eu.feeder.erje.net!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail Return-Path: 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; 'args': 0.04; 'aahz': 0.05; 'modify': 0.05; "'')": 0.07; 'args)': 0.07; 'arguments': 0.07; 'decorator': 0.07; 'wrapper': 0.07; '*is*': 0.09; 'arg': 0.09; 'foo,': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'subject:using': 0.09; 'wraps': 0.09; 'def': 0.10; 'functools': 0.16; 'pov,': 0.16; 'received:80.91.229.3': 0.16; 'received:dip.t-dialin.net': 0.16; 'received:plane.gmane.org': 0.16; 'received:t-dialin.net': 0.16; 'simpler,': 0.16; 'tempted': 0.16; 'y):': 0.16; 'wrote:': 0.17; 'helper': 0.17; 'typical': 0.17; '>>>': 0.18; 'changes': 0.20; 'parameters': 0.20; 'import': 0.21; 'latter': 0.22; 'simpler': 0.22; 'allows': 0.25; 'header :User-Agent:1': 0.26; 'header:X-Complaints-To:1': 0.28; 'post': 0.28; '>>>>': 0.29; 'subject:all': 0.29; 'probably': 0.29; 'becomes': 0.30; 'function': 0.30; 'expect': 0.31; 'code': 0.31; 'maintained': 0.33; 'traceback': 0.33; 'to:addr:python-list': 0.33; 'produced': 0.33; 'subject:?': 0.35; 'there': 0.35; 'received:org': 0.36; 'but': 0.36; 'client': 0.36; 'subject:: ': 0.38; 'to:addr:python.org': 0.39; 'header:Received:5': 0.40; 'kind': 0.61; 'needing': 0.62; 'more': 0.63; 'subject:there': 0.65; 'overall': 0.66; 'obvious': 0.71; 'article': 0.78; 'complexity': 0.84; 'otten': 0.84; 'subject:before': 0.84 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Peter Otten <__peter__@web.de> Subject: Re: Is there a simpler way to modify all arguments in a function before using the arguments? Date: Sun, 11 Nov 2012 10:28:55 +0100 Organization: None References: <18134e77-9b02-4aec-afb0-794ed900d194@googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7Bit X-Gmane-NNTP-Posting-Host: p5084948f.dip.t-dialin.net User-Agent: KNode/4.7.3 X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 60 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1352626145 news.xs4all.nl 6969 [2001:888:2000:d::a6]:54330 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:33124 Aahz wrote: > In article , > Peter Otten <__peter__@web.de> wrote: >>Miki Tebeka wrote: >> >>>> Is there a simpler way to modify all arguments in a function before >>>> using the arguments? >>> >>> You can use a decorator: >>> >>> from functools import wraps >>> >>> def fix_args(fn): >>> @wraps(fn) >>> def wrapper(*args): >>> args = (arg.replace('_', '') for arg in args) >>> return fn(*args) >>> >>> return wrapper >>> >>> @fix_args >>> def foo(x, y): >>> print(x) >>> print(y) >> >>I was tempted to post that myself, but he said /simpler/ ;) > > From my POV, that *is* simpler. When you change the parameters for foo, > you don't need to change the arg pre-processing. Also allows code reuse, > probably any program needing this kind of processing once will need it > again. Typical changes would be @fix_args def bar(x, y=None): print(x) print(y) @fix_args def baz(file, x, y): print(s, file=file) Do you find it obvious what bar("a_b") bar("a_b", y="c_d") print? Do you find the traceback produced by the latter helpful? Moving complexity into a helper function often makes client code simpler because if the helper is well-tested and preferrably maintained by someone else the part that you have to deal with becomes simpler, but the overall complexity still increases. A fix_args() decorator is worthwhile only if you need it more than once or twice, and because it is hard to generalise I expect that yagni.