220 5150 <2567b6ad-e4c3-4b4e-b0e9-ed0b3705687c@isocpp.org> article Path: news.gmane.org!not-for-mail From: Nicol Bolas Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: constexpr data member Date: Wed, 19 Jun 2013 18:24:01 -0700 (PDT) Lines: 97 Approved: news@gmane.org Message-ID: <2567b6ad-e4c3-4b4e-b0e9-ed0b3705687c@isocpp.org> References: <300a19dd-8a82-4788-9802-45170480b30a@isocpp.org> <63d90b03-5605-476d-b40b-7ebcee0d3354@isocpp.org> <0df105c5-7019-4674-83ac-1b071964210b@isocpp.org> <9a4c139d-b08f-4dab-b5a3-9ff9d3139061@isocpp.org> <1ef2b6fd-21f7-4492-a778-03952dd1720d@isocpp.org> <9a534f6b-4d07-4aa7-a164-4f713a3dd9ac@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_4726_23067070.1371691441158" X-Trace: ger.gmane.org 1371691448 10193 80.91.229.3 (20 Jun 2013 01:24:08 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 20 Jun 2013 01:24:08 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCEKFTV6ZUMBBMVTRGHAKGQEITHOVTA@isocpp.org Thu Jun 20 03:24:07 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ie0-f200.google.com ([209.85.223.200]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UpTba-0007dJ-7M for gclcip-std-proposals@m.gmane.org; Thu, 20 Jun 2013 03:24:06 +0200 Original-Received: by mail-ie0-f200.google.com with SMTP id x12sf27631886ief.7 for ; Wed, 19 Jun 2013 18:24:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-beenthere:date:from:to:message-id:in-reply-to:references:subject :mime-version:x-original-sender:reply-to:precedence:mailing-list :list-id:x-google-group-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe:content-type; bh=YTkXdKMkejsPo/JctVuTas8yLLtkJiJ7BaWfMo9xFFk=; b=PArEDoV6A9ZJdSYUOk0BH6iTAIH4qevGQY1giMePfRN4HOOiTmshVTaCcuvCeVNuSw i/qQfoG124PMLS43L9wDbjriH/qY1pTF7Ycf1Psy/70Rv+ZSq2K1J3zZ8ivO0+Ra+kwb L0t0tn7Fg6AuvOQFDNCyHVMjiYTtI0OdLn7FiE4unn0wAJr27VsrMoQtSb8vopUA/fq3 0+iMtIkkA315KgeY0u0z0bUS0l+Ju1wJvBMDpIxzN8tRF1Mllyxku5+Kwx7CT1jwp4z2 4piwB6l5rnWCM6gUNc8yLfmHkyWVrgQA4ztpdLejSp+SrGRwM13cYlfNhh01YMmOTxTU EKrg== X-Received: by 10.42.161.71 with SMTP id s7mr3893863icx.18.1371691444601; Wed, 19 Jun 2013 18:24:04 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.93.104 with SMTP id ct8ls80461igb.18.gmail; Wed, 19 Jun 2013 18:24:02 -0700 (PDT) X-Received: by 10.50.45.35 with SMTP id j3mr277737igm.3.1371691442270; Wed, 19 Jun 2013 18:24:02 -0700 (PDT) In-Reply-To: X-Original-Sender: jmckesson@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:5150 Archived-At: ------=_Part_4726_23067070.1371691441158 Content-Type: text/plain; charset=ISO-8859-1 On Wednesday, June 19, 2013 5:39:20 PM UTC-7, Zhihao Yuan wrote: > > On Wed, Jun 19, 2013 at 8:19 PM, Nicol Bolas > > wrote: > > The fact that the variable happens to be a constant doesn't change the > fact > > that it's still a variable. It represents an object; just an immutable > one. > > No, that's const, not constexpr. constexpr has the interfaces of an > object, like, can be taken address, but they can be regarded and > used as real constant. You can think of it as whatever you like; as far as the Standard for Programming Language C++ is concerned, it's a variable. It looks like a variable. It acts like a variable. It reacts in every way like a regular old variable as far as C++ is concerned. It has *storage* with a particular size, alignment, and memory location. They can be of pointer and reference types. And so forth. It is not a literal or macro or other kind of thing that just disappears into the aether after compilation. Yes, there are differences, but there are differences between a mutable variable and a `const` variable too. Yet they're both still *variables*. Just like `constexpr` variables are. We shouldn't make changes to the standard based on what someone wants to think of something as. We should make them based on what something is. And if you want to make a variable member-static, whether mutable, `const`, or `constexpr`, we already have syntax for that. -- --- 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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/. ------=_Part_4726_23067070.1371691441158 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On Wednesday, June 19, 2013 5:39:20 PM UTC-7, Zhihao Yuan wrote:On Wed, Jun 19, 2013 at 8:19 PM, Nicol Bo= las <jmck...@gmail.com> wrote:
> The fact that the variable happens to be a constant doesn't change= the fact
> that it's still a variable. It represents an object; just an immut= able one.

No, that's const, not constexpr.  constexpr has the interfaces of = an
object, like, can be taken address, but they can be regarded and
used as real constant.

You can think of it a= s whatever you like; as far as the Standard for Programming Language C++ is= concerned, it's a variable. It looks like a variable. It acts like a varia= ble. It reacts in every=20 way like a regular old variable as far as C++ is concerned. It has stora= ge with a particular size, alignment, and memory location. They can be = of pointer and reference types. And so forth.

It is not a literal or= macro or other kind of thing that just disappears into the aether after co= mpilation.

Yes, there are differences, but there are differences bet= ween a mutable variable and a `const` variable too. Yet they're both still = variables. Just like `constexpr` variables are.

We shouldn't = make changes to the standard based on what someone wants to think of someth= ing as. We should make them based on what something is. And if you want to = make a variable member-static, whether mutable, `const`, or `constexpr`, we= already have syntax for that.

--
 
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