220 31496 <26e2c972-3c64-4f62-a856-e7490621958e@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: Dan Raviv Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: overloading by constexpr (round 2?) Date: Tue, 7 Mar 2017 10:01:01 -0800 (PST) Lines: 149 Approved: news@gmane.org Message-ID: <26e2c972-3c64-4f62-a856-e7490621958e@isocpp.org> References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_891_2045239084.1488909661211" X-Trace: blaine.gmane.org 1488909669 4796 195.159.176.226 (7 Mar 2017 18:01:09 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 7 Mar 2017 18:01:09 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBC5YJREBWAGRBXPK7PCQKGQE5A5M25I@isocpp.org Tue Mar 07 19:01:05 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ua0-f200.google.com ([209.85.217.200]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1clJPw-0000RR-NJ for gclcip-std-proposals@m.gmane.org; Tue, 07 Mar 2017 19:01:00 +0100 Original-Received: by mail-ua0-f200.google.com with SMTP id 62sf18633594uas.1 for ; Tue, 07 Mar 2017 10:01:07 -0800 (PST) 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=rCyiTHeHaxWCRDyFk4SdveoTgj+BYloFq1BmujzfmgA=; b=e0fyXBYuuxwcJ3RsvCQ/iIIJA03ntlf4BbIyHDANtTw9OeMHsOoerY29/1M73Fq9dn Gu6kx1H2vgkcQUOwUwOBHQkbB/KNvruTV0WCvBzzXDJWeEz/Yg77X4/RYZevWk1k3V34 rQ1Lge3DPtp5hagtZthiUHuWcEihGTCCCGZHdUZHh63eBXQlDNYFeXjXb+B4mbWeNISr 03r8kGnmkHnWbIqqt/jQBZM9IbrhH9Ng4qwI71GCMsnND/cD+rCm/vt70Uwu5TUn5NGo I4FmfedgCmOf6cHlFaVictw18MfSlNLy5vPzbmzE/o/KJI1tYtQa6/g+LyVLg8Puauxv aOWQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; 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=rCyiTHeHaxWCRDyFk4SdveoTgj+BYloFq1BmujzfmgA=; b=sAfgrJ+zgJCO7fqilKbMWVfyBDGYrgS3dBwNaATznnKm/ovroscx/asSzoTzdclSx3 ET7YQDWBJ1hh95QkfC/syrXRaBN+WF9OsDlnRy5fMoR4xT4VLVMo/t+BilVuHbzEkFTr QZrlW/GmXo7yM4+o4qO3sEidQjgkb03R1MqF5huz2oQ4HeCu9JOrWAFJU/m/m17EA6kp en5LjkvCKhk9VYHKMIYuPFi9oIeiTC7oC9oTgtKBhfTXrjRJs4VJ6UMqhghl+EKsOqf2 Uq0LGy6PwWB+EekVw3e+h6GvBHzRwBsyG+4brhSes80ePJoIScD+gdjdusNMpxzG13q8 +QuQ== 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=rCyiTHeHaxWCRDyFk4SdveoTgj+BYloFq1BmujzfmgA=; b=cv/g87yCcpF3TmiT36BePaIKjxCo3uyq1yXTGzl+yZ0xClrBGHvOYJ815mq+jNquw+ Ljpqnp1ep5c7/qHY1pSE/XJ/vnCPVyRk/KX8xKCO5K+ntI2OCtp/rawGjFrHoZT/KIwu aQjNlW9NWHYWs7dzxBuWIiSyPCzG9rJynPS0S+zAz9axVStIjPuYU9XIKyk+eKozFd+r saIOoP+6KfQ119Gn60Mk71x1eyEhfrlzafK5ub8bA0XSnpMZZju0chXDWn49dyPADxr2 a5xvm/oOIAPK8VvtpnUwN+vkYzsaWxA+TPUc6j3Hy3kaGI/52Fa4JciKYK0A4nj9eGmq JQiQ== X-Gm-Message-State: AMke39nootljgFIJ8pv8pBWIbfCZSm9NFBQ72rnflRKlfO8pWkWWXYVI1buX27hJJvPyKA== X-Received: by 10.31.41.17 with SMTP id p17mr108513vkp.19.1488909662726; Tue, 07 Mar 2017 10:01:02 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.44.99 with SMTP id f90ls1197227otb.24.gmail; Tue, 07 Mar 2017 10:01:01 -0800 (PST) X-Received: by 10.157.32.3 with SMTP id n3mr301645ota.1.1488909661723; Tue, 07 Mar 2017 10:01:01 -0800 (PST) In-Reply-To: X-Original-Sender: dan.raviv@gmail.com 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:31496 Archived-At: ------=_Part_891_2045239084.1488909661211 Content-Type: multipart/alternative; boundary="----=_Part_892_959834260.1488909661212" ------=_Part_892_959834260.1488909661212 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable +1 It would remove one roadblock to making basic STL math/algorithm functions= =20 constexpr, since one argument against it is that a non-constexpr=20 implementation might allow for better runtime (when these functions indeed= =20 run at runtime). On Monday, March 6, 2017 at 8:15:54 PM UTC+2, dgutson wrote: > > I'm proposing the ability to provide two versions of a function,=20 > overloaded by the constexpr specifier: one constexpr version and another= =20 > non-constexpr version, and let the compiler use the appropriate one=20 > according to the context. > > A slightly similar subject has been discussed before ( > https://groups.google.com/a/isocpp.org/d/topic/std-proposals/oxijwTY-ft4/= discussion=20 > ). > Additionally, people seems to be interested in detecting constexpr-ness= =20 > (e.g.=20 > http://stackoverflow.com/questions/15232758/detecting-constexpr-with-sfin= ae)=20 > to achieve the same "manually". > > I'm talking about to make this simpler: > > constexpr int f() > { > return 1; > } > > int f() > { > return 2; > } > > constexpr auto a =3D f(); // a =3D 1 > auto fun =3D std::function(f); > int b =3D fun(); // b =3D 2 > > If there is some interest, I can star working in a gcc fork as a prototyp= e. > > BRgds, > > Daniel. > > > --=20 > Who=E2=80=99s got the sweetest disposition? > One guess, that=E2=80=99s who? > Who=E2=80=99d never, ever start an argument? > Who never shows a bit of temperament? > Who's never wrong but always right? > Who'd never dream of starting a fight? > Who get stuck with all the bad luck?=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. To view this discussion on the web visit https://groups.google.com/a/isocpp= ..org/d/msgid/std-proposals/26e2c972-3c64-4f62-a856-e7490621958e%40isocpp.or= g. ------=_Part_892_959834260.1488909661212 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
+1
It would remove one roadblock to making basic STL m= ath/algorithm functions constexpr, since one argument against it is that a = non-constexpr implementation might allow for better runtime (when these fun= ctions indeed run at runtime).

On Monday, March 6, 2017 at 8:= 15:54 PM UTC+2, dgutson wrote:
=
I'm proposing the ability to provide two ver= sions of a function,=20 overloaded by the constexpr specifier: one constexpr version and another non-constexpr version, and let the compiler use the appropriate one=20 according to the context.

A slightly similar subjec= t has been discussed before (https://groups.google.co= m/a/isocpp.org/d/topic/std-proposals/oxijwTY-ft4/discussion<= /a> ).
I'm talking about to make this simpler:
=
constexpr int f()
{
=C2=A0=C2=A0=C2=A0 return 1;<= br>
}

int f()
{
=C2=A0=C2=A0= =C2=A0 return 2;
}

constexpr auto a =3D f()= ;=C2=A0=C2=A0=C2=A0 // a =3D 1
auto fun =3D std::function<= int(void)>(f);
int b =3D fun();=C2=A0=C2=A0 // b =3D 2
=
If there is some interest, I can star working in a gcc = fork as a prototype.

BRgds,

=C2=A0=C2= =A0=C2=A0 Daniel.


--
Who=E2=80=99s got the s= weetest disposition?
One guess, that=E2=80=99s who?
Who=E2=80=99d nev= er, ever start an argument?
Who never shows a bit of temperament?
Who= 's never wrong but always right?
Who'd never dream of starting a= fight?
Who get stuck with all the bad luck?

--
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To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposa= ls+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/26e2c972-3c64-4f62-a856-e7490621958e= %40isocpp.org.
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