220 20018 <927D718C-8C9F-488C-8260-4E327DD41E22@gmail.com> article Path: news.gmane.org!not-for-mail From: David Krauss Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Obtaining the number of arguments of a function Date: Wed, 26 Aug 2015 07:49:24 +0800 Lines: 97 Approved: news@gmane.org Message-ID: <927D718C-8C9F-488C-8260-4E327DD41E22@gmail.com> References: <0a8b46d3-4b38-4e1b-ad75-9d18b4697a97@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 (Mac OS X Mail 8.2 \(2098\)) Content-Type: multipart/alternative; boundary="Apple-Mail=_68552155-0FEC-4B5C-B48F-CCCBA3FD05F5" X-Trace: ger.gmane.org 1440546581 17072 80.91.229.3 (25 Aug 2015 23:49:41 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 25 Aug 2015 23:49:41 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCW25A7E3QCRBCX66OXAKGQEL6F64AA@isocpp.org Wed Aug 26 01:49:33 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-io0-f197.google.com ([209.85.223.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZUNy7-0007v1-S0 for gclcip-std-proposals@m.gmane.org; Wed, 26 Aug 2015 01:49:32 +0200 Original-Received: by iodt126 with SMTP id t126sf355455993iod.0 for ; Tue, 25 Aug 2015 16:49:31 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:content-type:message-id:mime-version :subject:date:references:to:in-reply-to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=vBoEnqSRhFo614eKbk1kub7oGQaKPuXTi6WcrArpjNY=; b=UAVkKoL8n9/FuZPWRBMeMqKAVEPK1KYowMItQJHv9PuTh3T5+rdf5ORC63kzXN37gW lK5RKYRMW0zIs+QFgvH4OteOlU+f/w1g3oYsOHgsEUrjYSlTzKhQCEVzFZeNRpbGD5/q atS32ztPGrpZ/3Uu1DepwlakEd0dLvwcwVcrmALW4CM+1+YA8/nULiJ468zgMzcttr48 ducLq6mZCdymUQ4ZzOIAmV2aJn7HL2HRZr0LswvI2OSozyNeJZLp6WuYBTAV6iCO8rkL gGKdNH720bIh+rc2JB3v788tTefTAXRfUrmeNg8QNkDf7RvB9l8SnQrHTR+DxTbc3W+A v4Cw== X-Gm-Message-State: ALoCoQn2G82ShHaN+SUaIaa++cQ2JPYzGv9WbWEsemkvG4lT9SMzW0lmKo9C/+i6QXMfZZl04imh X-Received: by 10.50.50.179 with SMTP id d19mr5527899igo.6.1440546570955; Tue, 25 Aug 2015 16:49:30 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.150.7 with SMTP id y7ls299977iod.90.gmail; Tue, 25 Aug 2015 16:49:30 -0700 (PDT) X-Received: by 10.66.122.207 with SMTP id lu15mr61948104pab.146.1440546570280; Tue, 25 Aug 2015 16:49:30 -0700 (PDT) Original-Received: from mail-pa0-x231.google.com (mail-pa0-x231.google.com. [2607:f8b0:400e:c03::231]) by mx.google.com with ESMTPS id fp17si11970494pdb.150.2015.08.25.16.49.30 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 25 Aug 2015 16:49:30 -0700 (PDT) Received-SPF: pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:400e:c03::231 as permitted sender) client-ip=2607:f8b0:400e:c03::231; Original-Received: by pacti10 with SMTP id ti10so66446834pac.0 for ; Tue, 25 Aug 2015 16:49:30 -0700 (PDT) X-Received: by 10.66.62.202 with SMTP id a10mr62190716pas.42.1440546570132; Tue, 25 Aug 2015 16:49:30 -0700 (PDT) Original-Received: from [172.20.10.2] ([121.54.44.91]) by smtp.gmail.com with ESMTPSA id bu10sm22461986pac.36.2015.08.25.16.49.28 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 25 Aug 2015 16:49:29 -0700 (PDT) In-Reply-To: <0a8b46d3-4b38-4e1b-ad75-9d18b4697a97@isocpp.org> X-Mailer: Apple Mail (2.2098) X-Original-Sender: potswa@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:400e:c03::231 as permitted sender) smtp.mailfrom=potswa@gmail.com; dkim=pass header.i=@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:20018 Archived-At: --Apple-Mail=_68552155-0FEC-4B5C-B48F-CCCBA3FD05F5 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 > On 2015=E2=80=9308=E2=80=9326, at 7:21 AM, Sean Middleditch wrote: >=20 > This is just one piece of boost function_traits (http://www.boost.org/doc= /libs/1_57_0/libs/type_traits/doc/html/boost_typetraits/reference/function_= traits.html) combined with the utility to convert various forms of function= pointer into the "function type" needed by function_traits (e.g. https://f= unctionalcpp.wordpress.com/2013/08/05/function-traits/) >=20 > Very useful for script binding and general runtime reflection systems, am= ong other things. Take a look at libraries like luabind or one of its umpte= en bazillion alternatives for examples of where it can be useful. >=20 > Suuuper common need in games at the very least, and I'm sure many other p= laces. >=20 > Would be nice to have function_traits in the standard. The standard should be self-consistent. All the features should support the= other features. If you=E2=80=99re only interested in function signature types of the form R= et(Arg1, <=E2=80=A6>, ArgN), then as the blog post says, the signatures eas= ily map to and from tuples. Perhaps there should be a facility for doing th= at mapping. But it shouldn=E2=80=99t be called function_traits because such= a name would suggest much broader functionality. --=20 ---=20 You received this message because you are subscribed to the Google Groups "= ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposa= ls/. --Apple-Mail=_68552155-0FEC-4B5C-B48F-CCCBA3FD05F5 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=UTF-8
On 2015=E2=80=9308= =E2=80=9326, at 7:21 AM, Sean Middleditch <sean.middleditch@gmail.com> wrote:
=
Thi= s is just one piece of boost function_traits (http://www.boost.org/doc/libs/1_57_0/libs/typ= e_traits/doc/html/boost_typetraits/reference/function_traits.html) comb= ined with the utility to convert various forms of function pointer into the= "function type" needed by function_traits (e.g. https://f= unctionalcpp.wordpress.com/2013/08/05/function-traits/)

Very useful for script binding a= nd general runtime reflection systems, among other things. Take a look at l= ibraries like luabind or one of its umpteen bazillion alternatives for exam= ples of where it can be useful.

<= div class=3D"">Suuuper common need in games at the very least, and I'm sure= many other places.

Would be nice to have function_traits in the standard.

The standard should be self= -consistent. All the features should support the other features.
=
If you=E2=80=99re only interested in function sig= nature types of the form Ret(Arg1, <= =E2=80=A6>, ArgN), then as the blog post says, the signatures eas= ily map to and from tuples. Perhaps there should be a facility for doing th= at mapping. But it shouldn=E2=80=99t be called function_traits because such a name would suggest much broader= functionality.

--

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Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/<= /a>.
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