Path: csiph.com!x330-a1.tempe.blueboxinc.net!newsfeed.hal-mli.net!feeder1.hal-mli.net!weretis.net!feeder1.news.weretis.net!feeder.erje.net!newsfeed.xs4all.nl!newsfeed5.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 0.001 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; '(although': 0.05; 'args': 0.07; 'subject:two': 0.07; 'python': 0.08; 'subject:parameters': 0.09; 'pm,': 0.10; 'def': 0.12; 'received:209.85.214.174': 0.14; 'received:mail-iw0-f174.google.com': 0.14; 'wrote:': 0.14; 'overrides': 0.16; 'rohdewald': 0.16; 'scope.': 0.16; 'subject:function': 0.16; 'wolfgang': 0.16; 'obviously': 0.17; 'tue,': 0.17; 'language': 0.18; 'wrap': 0.19; 'header:In-Reply- To:1': 0.21; 'modify': 0.22; 'function': 0.25; 'object': 0.26; 'message-id:@mail.gmail.com': 0.28; 'received:209.85.214': 0.28; '(you': 0.29; 'effect': 0.29; 'explicitly': 0.29; 'class': 0.29; 'changes': 0.30; 'seem': 0.32; 'done': 0.32; 'to:addr:python- list': 0.33; 'too': 0.33; 'things': 0.33; '...': 0.34; 'daniel': 0.34; 'function.': 0.35; 'or,': 0.37; 'received:google.com': 0.37; 'change': 0.37; 'received:209.85': 0.37; '(to': 0.37; 'ways': 0.37; 'but': 0.38; 'subject:: ': 0.38; 'some': 0.38; 'subject: (': 0.39; 'received:209': 0.39; 'to:addr:python.org': 0.39; 'really': 0.40; 'best': 0.60; '31,': 0.65 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type; bh=1+jKP9y9iiRbg6zZBaZi2oVv7pWKSoRX/6XAyURso38=; b=xL89MfsQlxSyxgyJHYjNSfdqab6Ry/nmvOLioI2zj2hgjTFX7yuDUZdQLVF2EKuDYV ZP3Q1IcCxNNBIqRfHKV/MmgvrfU1KwHexxatQm3koViyTgKM23VTbqm5rH2QM9YrZTw2 PMhUCplFVWhNo3Gu2A+vl19pJ5gdr4GeVhGKU= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=l/a1/1UVytiFk1I8508W4SpwpczdX8o1dgZ0uuDPQHN3onL90fPXv/UmERnPcph1Dw DMAHPtnLqpCHYKuZo0GDlt3COcVHZbaGa/KOx9XEbzEF2UzZvfnFrN21Sxsd0RQZbsFg kK7tzZSYdnTE+ZuSJwUl2y8cm7AAaN2mdCkCE= MIME-Version: 1.0 In-Reply-To: <201105310713.24842.wolfgang@rohdewald.de> References: <201105310713.24842.wolfgang@rohdewald.de> Date: Tue, 31 May 2011 16:36:33 +1100 Subject: Re: scope of function parameters (take two) From: Daniel Kluev To: python-list@python.org Content-Type: text/plain; charset=ISO-8859-1 X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.12 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: 26 NNTP-Posting-Host: 82.94.164.166 X-Trace: 1306820196 news.xs4all.nl 49182 [::ffff:82.94.164.166]:53952 X-Complaints-To: abuse@xs4all.nl Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:6708 On Tue, May 31, 2011 at 4:13 PM, Wolfgang Rohdewald wrote: > what you really seem to want is that a function by default > cannot have any side effects (you have a side effect if a > function changes things outside of its local scope). But > that would be a very different language than python This can be done in Python (to some degree), like this @copy_args def somefunc(a, b, c): ... where copy_args would explicitly call deepcopy() on all args passed to the function. Or, to save some performance, wrap them in some CopyOnEdit proxy (although this is tricky, as getattr/getitem can modify object too if class overrides them). Obviously it would not save you from functions which use global/globals() or some other ways to change state outside their scope. -- With best regards, Daniel Kluev