220 26313 <55892254-d646-4cc3-b10c-a0f0a5eb665c@isocpp.org> article Path: news.gmane.org!not-for-mail From: Giovanni Piero Deretta Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: statement folding on variadic templates parameters pack Date: Mon, 13 Jun 2016 02:33:25 -0700 (PDT) Lines: 83 Approved: news@gmane.org Message-ID: <55892254-d646-4cc3-b10c-a0f0a5eb665c@isocpp.org> References: <1e3daa7c-e10a-4589-8118-26f47bc1a0df@isocpp.org> <2d8458f8-27b2-464f-a16e-fc866ccfd2cd@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_131_1998868029.1465810405949" X-Trace: ger.gmane.org 1465810412 9202 80.91.229.3 (13 Jun 2016 09:33:32 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 13 Jun 2016 09:33:32 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDEP3I7TGEIOP67ZXICRUBBT6Z7F2@isocpp.org Mon Jun 13 11:33:32 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qk0-f197.google.com ([209.85.220.197]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1bCOFN-0000HJ-4Q for gclcip-std-proposals@m.gmane.org; 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Mon, 13 Jun 2016 02:33:28 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.107.34.142 with SMTP id i136ls1519717ioi.55.gmail; Mon, 13 Jun 2016 02:33:27 -0700 (PDT) X-Received: by 10.36.68.65 with SMTP id o62mr218387ita.0.1465810407154; Mon, 13 Jun 2016 02:33:27 -0700 (PDT) In-Reply-To: X-Original-Sender: gpderetta@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:26313 Archived-At: ------=_Part_131_1998868029.1465810405949 Content-Type: multipart/alternative; boundary="----=_Part_132_383559435.1465810405949" ------=_Part_132_383559435.1465810405949 Content-Type: text/plain; charset=UTF-8 On Sunday, June 12, 2016 at 11:25:50 AM UTC+1, Ville Voutilainen wrote: > > On 12 June 2016 at 13:23, > wrote: > > This code should be fast as manually written switch, it would be trivial > for > > compiler to create jump table to have best performance. > > > I'm sure the open-source compilers will happily accept an extension > patch that shows how trivial it is. > For what is worth, you can abuse GCC statement expressions plus variadics to get variadic expansion of switch statements. Although 'case' in statement expressions is explicitly documented not to be supported, it does work in practice (nothing I would use in production of course). So, while I wouldn't call it trivial, it seems to me that it souldn't be too hard to implement the extension in GCC, and you could even consider statement expressions as existing practice. -- gpd -- 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 email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/55892254-d646-4cc3-b10c-a0f0a5eb665c%40isocpp.org. ------=_Part_132_383559435.1465810405949 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On Sunday, June 12, 2016 at 11:25:50 AM UTC+1, Ville Vouti= lainen wrote:
On 12 June 2016 a= t 13:23, =C2=A0<inkwizyt...@gmail.com> wrote:
> This code should be fast as manually written switch, it would be t= rivial for
> compiler to create jump table to have best performance.


I'm sure the open-source compilers will happily accept an extension
patch that shows how trivial it is.

For what is worth, you can abuse GCC statement ex= pressions plus variadics to get variadic expansion of switch statements. Al= though 'case' in statement expressions is explicitly documented not= to be supported, it does work in practice (nothing I would use in producti= on of course).

So, while I wouldn't call it trivial, it seems to= me that it souldn't be too hard to implement the extension in GCC, and= you could even consider statement expressions as existing practice.
-- gpd

--
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To post to this group, send email to std-proposals@isocpp.org.
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