Path: csiph.com!newsfeed.hal-mli.net!feeder3.hal-mli.net!newsfeed.hal-mli.net!feeder1.hal-mli.net!newsfeed.xs4all.nl!newsfeed4.news.xs4all.nl!xs4all!newsgate.cistron.nl!newsgate.news.xs4all.nl!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; 'argument': 0.04; 'interpreter': 0.04; 'cpython': 0.05; 'arguments': 0.07; 'python': 0.09; '*args):': 0.09; 'arg': 0.09; 'commonly': 0.09; 'counting': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'runtime': 0.09; 'tuple': 0.09; 'def': 0.10; 'extensions': 0.13; 'from:addr:behnel.de': 0.16; 'from:addr:stefan_ml': 0.16; 'from:name:stefan behnel': 0.16; 'python."': 0.16; 'received:80.91.229.3': 0.16; 'received:dip0.t-ipconnect.de': 0.16; 'received:plane.gmane.org': 0.16; 'received:t-ipconnect.de': 0.16; 'certainly': 0.17; 'else,': 0.17; 'pointer': 0.17; 'stefan': 0.17; 'appropriate': 0.20; 'putting': 0.20; 'written': 0.20; "i've": 0.23; 'external': 0.24; 'header:In-Reply-To:1': 0.25; 'header:User-Agent:1': 0.26; 'common': 0.26; 'skip:m 30': 0.26; 'plain': 0.27; 'thoughts': 0.27; 'header:X-Complaints-To:1': 0.28; 'convert': 0.29; 'manual': 0.29; 'objects': 0.29; 'skip:_ 10': 0.29; 'class': 0.29; 'saves': 0.30; 'code': 0.31; 'to:addr:python- list': 0.33; 'another': 0.33; 'subject:?': 0.35; 'similar': 0.35; 'something': 0.35; 'received:org': 0.36; 'should': 0.36; 'skip:p 20': 0.36; 'quite': 0.37; 'subject:: ': 0.38; 'easier': 0.38; 'object': 0.38; 'things': 0.38; 'nothing': 0.38; 'instead': 0.39; 'to:addr:python.org': 0.39; 'header:Received:5': 0.40; 'email addr:gmail.com,': 0.65; 'received:87.139': 0.84; 'subject:necessary': 0.84 X-Injected-Via-Gmane: http://gmane.org/ To: python-list@python.org From: Stefan Behnel Subject: Re: Is PyArg_ParseTuple necessary to parse arguments? Date: Wed, 23 Jan 2013 08:50:23 +0100 References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Gmane-NNTP-Posting-Host: p578ba676.dip0.t-ipconnect.de User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 In-Reply-To: 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: 30 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1358927435 news.xs4all.nl 6985 [2001:888:2000:d::a6]:59207 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:37424 rahulgarg44@gmail.com, 22.01.2013 18:20: > Or can I just loop through the argument tuple manually by using something like PyTuple_GET_ITEM(args,i), then putting manual code to convert the objects to appropriate C type? > The use case is that I am interfacing Python with another interpreter and do not know the type and number of arguments till runtime :) Just in case you're not aware of it, C extensions are quite commonly written in Cython instead of C these days. I've used it for Lupa, for example, which embeds the Lua(JIT) runtime in CPython. That should be quite similar to what you're after. It certainly makes things a lot easier to write cdef class Wrapper: "Wraps an external object for usage in Python." cdef mylib.sometype* _wrapped_object # pointer to external 'thing' def __call__(self, *args): mapped_args = malloc(len(args)*...) # ... for i, arg in enumerate(args): map_value_to_external(arg, mapped_args[i]) # ... result = call_external(self._wrapped_object, mapped_args) return map_value_from_external(result) than to do these things in plain C. If nothing else, it saves you from having to put thoughts into reference counting and other common CPython C-API pitfalls. Stefan