220 14875 article Path: news.gmane.org!not-for-mail From: =?UTF-8?Q?Germ=C3=A1n_Diago?= Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Safer C++: never allow implicitly uninitialized variables? Date: Sat, 6 Dec 2014 13:13:31 +0700 Lines: 128 Approved: news@gmane.org Message-ID: References: <4720a9a6-24d5-4488-a229-2bdf2433fa03@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=001a113d2eaee9df4b05098618f1 X-Trace: ger.gmane.org 1417846440 3670 80.91.229.3 (6 Dec 2014 06:14:00 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 6 Dec 2014 06:14:00 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDC2VXM4YYDRBIF5RKSAKGQEYU5A4VQ@isocpp.org Sat Dec 06 07:13:54 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yh0-f69.google.com ([209.85.213.69]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Xx8cr-0000AM-SL for gclcip-std-proposals@m.gmane.org; Sat, 06 Dec 2014 07:13:54 +0100 Original-Received: by mail-yh0-f69.google.com with SMTP id 29sf5375660yhl.8 for ; Fri, 05 Dec 2014 22:13:53 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:content-type:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe; bh=6FKWaNCZZcH3UhRSQprMdB8pfMQFj8HnxSUL3E3LNr4=; b=FZe4Ujbld9JGztCOoZWZz/c86rIqe25j6qYVSsUPnbTMq9yrPLgSelp7jdFCAZFzXn Sm5FBcjw2Jpj/ZEWbEJNfMmqmWN4Z0EXxLO9kgxGcAm49NjoktEY90Hu9giLF6nsU2iE cU++JRLXYtpZtGbE5H2OcXnCDOeWw51eEv1JAZp+uBALuG0XPwlSZum9mNHe7j9vf8ZI m4r2OltnjFBZwYKihJdxU4SE76XPKfE0eqjPgNrXf/B5+mYA6EquakdnIgqUBd8TAwNm C4PmUIq+iO48gLDqUs1qhclXoxCSM7JwXd+i2jXh2R6je9rf9GAh51Z12SF07UOwpr9f GCtA== X-Gm-Message-State: ALoCoQlCuXWCuw/R5vAYqpl7BrA5Z6bZyNA/YjmYJCl9kkURxffhkq2Xtt1Q0T2puPocyzf6Vxa3 X-Received: by 10.236.39.83 with SMTP id c59mr18041067yhb.45.1417846432772; Fri, 05 Dec 2014 22:13:52 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.182.196.10 with SMTP id ii10ls698090obc.48.gmail; Fri, 05 Dec 2014 22:13:51 -0800 (PST) X-Received: by 10.202.137.139 with SMTP id l133mr576390oid.123.1417846431928; Fri, 05 Dec 2014 22:13:51 -0800 (PST) Original-Received: from mail-oi0-x22f.google.com (mail-oi0-x22f.google.com. [2607:f8b0:4003:c06::22f]) by mx.google.com with ESMTPS id w4si21177078oia.101.2014.12.05.22.13.51 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 05 Dec 2014 22:13:51 -0800 (PST) Received-SPF: pass (google.com: domain of germandiago@gmail.com designates 2607:f8b0:4003:c06::22f as permitted sender) client-ip=2607:f8b0:4003:c06::22f; Original-Received: by mail-oi0-f47.google.com with SMTP id v63so1437191oia.34 for ; Fri, 05 Dec 2014 22:13:51 -0800 (PST) X-Received: by 10.202.216.11 with SMTP id p11mr633924oig.47.1417846431799; Fri, 05 Dec 2014 22:13:51 -0800 (PST) Original-Received: by 10.182.162.6 with HTTP; Fri, 5 Dec 2014 22:13:31 -0800 (PST) In-Reply-To: <4720a9a6-24d5-4488-a229-2bdf2433fa03@isocpp.org> X-Original-Sender: germandiago@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of germandiago@gmail.com designates 2607:f8b0:4003:c06::22f as permitted sender) smtp.mail=germandiago@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-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:14875 Archived-At: --001a113d2eaee9df4b05098618f1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable P.S.: sorry for the typos. 2014-12-06 13:10 GMT+07:00 Germ=C3=A1n Diago : > Hello everyone, > > I wonder if it would make sense to make variables in C++ automatically > value-initialized or there would be problems. > > Since we are making c++ safer and safer, would it make sense to do the > following? > > > int a; //value-initialized to 0 > > Later, some syntax like in D language could be provided: > > int a =3D void; > > > The rationale behind this change would be: > > - an uninitialized variable that is replaced by these new semantics does > not produce incorrect behaviour. > - makes the language safer to use. > > In the case where performance must be preserved, a compiler option with > the old semantics would be enough. > > Would this make any sense or I am missing manu points? It looks to me tha= t > this could be backwards-compatible > and the noly thing that could happen is a performance bug, which can be > solved replacing iniitialization or by a > compiler switch for large codebases. > > > > -- > > --- > 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/. > --=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/. --001a113d2eaee9df4b05098618f1 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
P.S.: sorry for the typos.

2014-12-06 13:10 GMT+07:00 Germ=C3=A1n Diag= o <germandiago@gmail.com>:
Hello everyone,

I wonder if it wou= ld make sense to make variables in C++ automatically value-initialized or t= here would be problems.

Since we are making c++ sa= fer and safer, would it make sense to do the following?


int a; //value-initialized to 0

Later, some syntax like in D language could be provided:

<= /div>
int a =3D void;


The ratio= nale behind this change would be:

- an uninitializ= ed variable that is replaced by these new semantics does not produce incorr= ect behaviour.
- makes the language safer to use.

<= /div>
In the case where performance must be preserved, a compiler optio= n with the old semantics would be enough.

Would th= is make any sense or I am missing manu points? It looks to me that this cou= ld be backwards-compatible
and the noly thing that could happen i= s a performance bug, which can be solved replacing iniitialization or by a<= /div>
compiler switch for large codebases.
=



--

---
You received this message because you are subscribed to the Google Groups &= quot;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/gro= up/std-proposals/.

--

---
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
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.
Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/<= /a>.
--001a113d2eaee9df4b05098618f1-- .