220 32562 article Path: news.gmane.org!.POSTED!not-for-mail From: ma.kalbfuss@web.de Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: relaxing rules for ternary operator. Allow incompatible types. Date: Sun, 21 May 2017 13:54:51 -0700 (PDT) Lines: 110 Approved: news@gmane.org Message-ID: References: <1b5ee8eb-53df-4e98-af2f-829c7bc2e5b2@isocpp.org> <99350a9e-0c6b-468d-9761-f2b2b052275e@isocpp.org> <27694795.c6R7qxKFE5@tjmaciei-mobl1> <1678895.0nQhqNqFQE@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_2482_558607628.1495400092089" X-Trace: blaine.gmane.org 1495400096 11664 195.159.176.226 (21 May 2017 20:54:56 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 21 May 2017 20:54:56 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBC7YTI72XQOBBHH5Q7EQKGQEVRZUF7I@isocpp.org Sun May 21 22:54:50 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ua0-f198.google.com ([209.85.217.198]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dCXsH-0002qK-Kg for gclcip-std-proposals@m.gmane.org; Sun, 21 May 2017 22:54:50 +0200 Original-Received: by mail-ua0-f198.google.com with SMTP id w13sf28768995uaw.11 for ; Sun, 21 May 2017 13:54:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=H6N7w25Os0wcF5z4NOb1rD6YqueH/04Hc4NjjQv8jEM=; b=pToICQWVLcoPGDdx0snN3qI19gF6xXK/2CWm2EMUQXEUZzZzSgJPC/wHRVZHpXANOO AlpfumzqLbdSvTCLIljpy8Z2Db90wARtSsC4oFavB0/JJDnHGX8iYy0VzmPg7wKCtubV oxlrqwyfV3aWOgwRu++GrAve1el2HTwqhTtbYB4zYmI3zD1xfLir3nUUdfBemnYrnBp3 iBXL0pxO+V82le3rIerTXMDoFEBYaMwQHcKU/UTy2PcJVHFlKAY6m/8/GrlIsA6Fgxnx bt5ReX9wgMs1nQKjwB9w0bmGs2+J1Sv0KZgDdXHM8A6Q/3F7ITTJys71SpSCdbELgPzJ 4caw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:message-id:in-reply-to:references :subject:mime-version:x-original-sender:reply-to:precedence :mailing-list:list-id:x-spam-checked-in-group:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=H6N7w25Os0wcF5z4NOb1rD6YqueH/04Hc4NjjQv8jEM=; b=JADmv9b8eIKZhp9/5KBLocT8G2pBsKR7pnMoG0nCeOC041jRndQzABpRFmBTQvDfCt halvqZEGEqGO41co7++TOy62qMOE4k04Gk2pw4E3ITjl2FmieL4JVznDnZh9Gx7H8Q2y a/OpEwFVVmdaSgUxjQEA0xGntMkXJYyBoe6wj5P++jZKo8yODJXuqUpnBoNFOioZTJOu meqaWColP1v6bpjSolCgyBTKbH3S16EodaxWDeyqXktKF86REB2HsYv5Cfydy3ahZUE8 k80NYmYOXteZLMwd8A3/ySRzFr3yYiRdp1AIvl8Ka5+lcDbcvv/bRLzo2cs1o1woLpq6 YF/g== X-Gm-Message-State: AODbwcDZRRvxQQ6hActQgba4/xyylRbHAF8Gqky8kOvDK72Ye4Xg+/o3 XeLMDMSpzHoMowW+ X-Received: by 10.31.128.74 with SMTP id b71mr5681333vkd.16.1495400093580; Sun, 21 May 2017 13:54:53 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.68.164 with SMTP id v36ls2474826ote.28.gmail; Sun, 21 May 2017 13:54:52 -0700 (PDT) X-Received: by 10.157.45.79 with SMTP id v73mr419767ota.20.1495400092729; Sun, 21 May 2017 13:54:52 -0700 (PDT) In-Reply-To: <1678895.0nQhqNqFQE@tjmaciei-mobl1> X-Original-Sender: ma.kalbfuss@web.de Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: 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:32562 Archived-At: ------=_Part_2482_558607628.1495400092089 Content-Type: multipart/alternative; boundary="----=_Part_2483_121770391.1495400092089" ------=_Part_2483_121770391.1495400092089 Content-Type: text/plain; charset="UTF-8" Yeah, i realize that. This is something you have to consider if you're using templates extensively. This is not the right solution for everything. I think in most cases, you use one or at most two ternary operators in one place. For three or more ternary operators the runtime overhead is assumably the lesser of two evils. But even if it grows exponentially, the constants are pretty small. Normaly only a few instructions are involved. Am Sonntag, 21. Mai 2017 19:17:03 UTC+2 schrieb Thiago Macieira: > > On domingo, 21 de maio de 2017 10:08:16 PDT Thiago Macieira wrote: > > You do realise this grows exponentially, right? > > > > auto x = runtime_condition ? A{} : B{}; > > auto y = runtime_condition ? C{} : D{}; > > auto z = runtime_condition ? E{} : F{}; > > I mean different runtime conditions here. > > > x.f() + y.f() + z.f(); > > > > There are 8 different branches there to make the above work. > > > -- > Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org > Software Architect - Intel Open Source Technology Center > > -- 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/b75d4532-bb6e-4b66-8f9b-a2a94b679e96%40isocpp.org. ------=_Part_2483_121770391.1495400092089 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Yeah, i realize that. This is something you have to consid= er if you're using templates extensively. This is not the right solutio= n for everything. I think in most cases, you use one or at most two ternary= operators in one place. For three or more ternary operators the runtime ov= erhead is assumably the lesser of two evils. But even if it grows exponenti= ally, the constants are pretty small. Normaly only a few instructions are i= nvolved.

Am Sonntag, 21. Mai 2017 19:17:03 UTC+2 schrieb Thiago Maci= eira:
On domingo, 21 de maio de= 2017 10:08:16 PDT Thiago Macieira wrote:
> You do realise this grows exponentially, right?
>=20
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 auto x =3D runtime_condition ? A{} : B= {};
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 auto y =3D runtime_condition ? C{} : D= {};
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 auto z =3D runtime_condition ? E{} : F= {};

I mean different runtime conditions here.

> =C2=A0 =C2=A0 =C2=A0 =C2=A0 x.f() + y.f() + z.f();
>=20
> There are 8 different branches there to make the above work.


--=20
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
=C2=A0 =C2=A0Software Architect - Intel Open Source Technology Center

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