220 12731 <7e67bd2a-1a06-4ee7-8f21-8b2f8bfeeb84@isocpp.org> article Path: news.gmane.org!not-for-mail From: Matthew Fioravante Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Local variables that overstay their welcome Date: Mon, 8 Sep 2014 10:54:47 -0700 (PDT) Lines: 71 Approved: news@gmane.org Message-ID: <7e67bd2a-1a06-4ee7-8f21-8b2f8bfeeb84@isocpp.org> References: <778b6fbf-3b58-488c-9e51-32a05b95831e@isocpp.org> <94e564fc-f769-48d0-8a61-264f9c8f8480@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_765_1913358570.1410198888010" X-Trace: ger.gmane.org 1410198899 5288 80.91.229.3 (8 Sep 2014 17:54:59 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 8 Sep 2014 17:54:59 +0000 (UTC) Cc: rgumpertz@gmail.com To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDELF54RTIGRB2G2W6QAKGQEC3ZZKQI@isocpp.org Mon Sep 08 19:54:50 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pd0-f199.google.com ([209.85.192.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XR39O-0008KC-AC for gclcip-std-proposals@m.gmane.org; Mon, 08 Sep 2014 19:54:50 +0200 Original-Received: by mail-pd0-f199.google.com with SMTP id v10sf36117243pde.6 for ; Mon, 08 Sep 2014 10:54:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version:x-original-sender:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe:content-type; bh=tFJKj0dSlUzaRX9U1Uq5yRCLYSGjZk8WoudjdeN4mHI=; b=0aJ4300I/Kje7SCLffXTiq60MdYBbp9rD+48Ws0VXlb+UzT/3wFhFFWDpSvLL9jpTF QLF9ObTuzZQ9UuC40umIHbWiU5aSvCfHj95gl33lhDDgrgfN4f7694zfTEtKxIE5oza4 +IXsENGUpNXwyuNLI6kCRvkFPyHWB+6FcV/uZ+JeJSQmvnNWian+IHDXZVuRdzDJGara XRimjX/I3ZW/+MDRivH5uwySHpBBL/HZfIC8cTCcI280svOQKICwKV+pKYyrKIAOVUl8 KhziHh4koOccjyzD/Iwg+3mTS/eN2k7YVkMUwdUyae6E67PTF8iB5EVqfYBiVxwWntPB 3Pxg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:x-original-sender:reply-to :precedence:mailing-list:list-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe:content-type; bh=tFJKj0dSlUzaRX9U1Uq5yRCLYSGjZk8WoudjdeN4mHI=; b=QbqXhNil/1Q8XkD9Qs8M7hLAtmL7T+qljXnN9AATRpPnaroXEhrJPnyXIKIfPRHnZG jDVUMXpmDD7z7a0um7l+5rll2SRhArNRnWWTTVw/etDMrm5wTCtRcUKHwodILrlMTng3 uiyhRK3xkAnGr2dbyW4enS+s3IeGBEH8LSUU7tIPYP3JfsKJWhkINvOHR0gNvuqh0Y/U 8bMcbLarfEgDGDSIy4Abv15eb4j1CONoNHJURM/0H/PU3hfjAcvmDP37Jq5c8fyIVA0y /Ku1Xy8gsGfmsTOKdqRL0fCRBNZokT6R6jnB31gyhuoufJAhdG6wgIyWXRRvY6QFrnIa Qn8Q== X-Gm-Message-State: ALoCoQn9C8YKuY6yI69lzPbFurCdh5tqVhto0FsFHU+T/yGhklYVaoS6zoPA1BXTZtYvY0ejTxfx X-Received: by 10.66.162.162 with SMTP id yb2mr8410558pab.39.1410198889231; Mon, 08 Sep 2014 10:54:49 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.140.96.42 with SMTP id j39ls1805142qge.89.gmail; Mon, 08 Sep 2014 10:54:48 -0700 (PDT) X-Received: by 10.140.18.161 with SMTP id 30mr22362qgf.31.1410198888491; Mon, 08 Sep 2014 10:54:48 -0700 (PDT) In-Reply-To: <94e564fc-f769-48d0-8a61-264f9c8f8480@isocpp.org> X-Original-Sender: fmatthew5876@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:12731 Archived-At: ------=_Part_765_1913358570.1410198888010 Content-Type: text/plain; charset=UTF-8 On Sunday, September 7, 2014 6:31:13 PM UTC-4, rgum...@gmail.com wrote: > > It looks to me like this is one case of a more general desire: > (1) tell the compiler that a local variable should be treated as const > for the remainder of the containing block > That could easily be implemented using the current proposal: Foo x; //do non-const stuff with x const auto& xc = x; kill x; //do const operations on xc I think changing the type of x itself to be const in the middle of the block would be a very bad idea. It makes the code very hard to read if the type can change anywhere. Also it could have disastrous consequences for templates. -- --- 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_765_1913358570.1410198888010 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable


On Sunday, September 7, 2014 6:31:13 PM UTC-4, rgu= m...@gmail.com wrote:
It looks to me like this is one case of a mo= re general desire:
    (1) tell the compiler that a local= variable should be treated as const for the remainder of the containing bl= ock

That could easily be impleme= nted using the current proposal:

Foo x;
//do non-const stuff with= x
const auto& xc =3D x;
kill x;
//do const operations on xc
I think changing the type of x itself to be const in the middle of th= e block would be a very bad idea. It makes the code very hard to read if th= e type can change anywhere. Also it could have disastrous consequences for = templates.

 

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