220 31910 article Path: news.gmane.org!.POSTED!not-for-mail From: Vitali Lovich Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: This variable should not be named: an identifier (not) to remember Date: Thu, 30 Mar 2017 21:41:56 +0000 Lines: 151 Approved: news@gmane.org Message-ID: References: <985b9b2a-c734-45eb-95f4-db4dc0d309a1@isocpp.org> <2235919.4GAIbDEcRC@tjmaciei-mobl1> <3760122.IY8cFr858X@tjmaciei-mobl1> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=001a113cff84817262054bf990a2 X-Trace: blaine.gmane.org 1490910127 28464 195.159.176.226 (30 Mar 2017 21:42:07 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Thu, 30 Mar 2017 21:42:07 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCFIZX46Q4HRBL7X6XDAKGQER3LSCDY@isocpp.org Thu Mar 30 23:42:03 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-pg0-f70.google.com ([74.125.83.70]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1cthpS-0006sS-LT for gclcip-std-proposals@m.gmane.org; Thu, 30 Mar 2017 23:42:02 +0200 Original-Received: by mail-pg0-f70.google.com with SMTP id 81sf59230428pgh.3 for ; Thu, 30 Mar 2017 14:42:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=bO+VK19TYUcgHNmrBPXc+4yHDzy+HNZi9CHSCPGkAD8=; b=ZdIQ05hqzXc3LPS1WYxbRQtYF8CNWnIPxP4fiP7aoO9wXYGIRBX2jtL8Bq2Fh5awRU 0ams56mAYntPYayn9xkVRsG/41H8uWEl283d8ar19AlgpuO47onGG87SHFfVadGqY33p oU5c+0BUhVTEg0OTdsvqu0x0FOtFR2/r7XKKYkCWjFBzFwqfEHUV46HF2UoHxecojpTF h9GpQ5iAVufJ3x4oMp8RZNMyQOOflipPKbPir/k5ieSNMomT/Xqiuyza/Q7CimuYSeHa aGhWNyN+UyqmQcTU2WizwAXPoHWGGQgPNoVcRx5AZwY7+/HIh24Z0ogXIM21vX3P6wZz A5oQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=bO+VK19TYUcgHNmrBPXc+4yHDzy+HNZi9CHSCPGkAD8=; b=OzRynFlf7AD6yNAzxvKsfy12QpYjNCMK9byH7sSsl55x7ClrfSNANBmxESXTKrhYHD TkjhXwi1pI4IHWIGfbrcpxgFpBERAJgG+Ld3D+z4EGdGFk61Db4A1NWit5rXWya4RBMH a0RjRmCLZSxrmv5jpgzhVmj3QhKiHO9U7hisBjO2VO9KCv1acE993uMKSZ//TFzYBX+T XAV685iBkQz6yAF7VCNtRvtKamvUwq/8hDfzH9D49iLYDLAITjSqm4Ikht15SlfwsAT1 XTWUEKtk4v43piFkwC9CBj6711IGHfJ2ALTRBBE5gCZqHHKgO2a36rHZxvdUFflnotOf ct/g== X-Gm-Message-State: AFeK/H1nUVQfdX8aZWixT7OOP1legwTXlAOBfzczYtD+Rn9sWo3FmvO2wb1mS9VlNlmPAw== X-Received: by 10.99.185.21 with SMTP id z21mr727195pge.40.1490910128209; Thu, 30 Mar 2017 14:42:08 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.43.209 with SMTP id u75ls1266801ota.13.gmail; Thu, 30 Mar 2017 14:42:07 -0700 (PDT) X-Received: by 10.157.60.99 with SMTP id j32mr1362331ote.172.1490910127460; Thu, 30 Mar 2017 14:42:07 -0700 (PDT) Original-Received: from mail-oi0-x231.google.com (mail-oi0-x231.google.com. [2607:f8b0:4003:c06::231]) by mx.google.com with ESMTPS id g69si1700994otg.12.2017.03.30.14.42.07 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 30 Mar 2017 14:42:07 -0700 (PDT) Received-SPF: pass (google.com: domain of vlovich@gmail.com designates 2607:f8b0:4003:c06::231 as permitted sender) client-ip=2607:f8b0:4003:c06::231; Original-Received: by mail-oi0-x231.google.com with SMTP id o67so44196344oib.1 for ; Thu, 30 Mar 2017 14:42:07 -0700 (PDT) X-Received: by 10.157.45.54 with SMTP id v51mr1356935ota.220.1490910126893; Thu, 30 Mar 2017 14:42:06 -0700 (PDT) In-Reply-To: X-Original-Sender: vlovich@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of vlovich@gmail.com designates 2607:f8b0:4003:c06::231 as permitted sender) smtp.mailfrom=vlovich@gmail.com; dmarc=pass (p=NONE sp=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:31910 Archived-At: --001a113cff84817262054bf990a2 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Ah. But I forgot now that with structured binding there's a hidden local variable anyway for the tuple itself. I was thinking the compiler was smart and applied RVO to the individual elements directly. On Thu, Mar 30, 2017 at 2:40 PM Vitali Lovich wrote: > tuple, string_view> getstr() > > The 2nd argument is a view into the string owned by shared_ptr. > > The semantics of whether or not the string view points to owned memory > depends on the lifetime of the shared_ptr and my understanding of what yo= u > were saying is that the lifetime changes depending on whether the get() i= s > done or ignored. > > On Wed, Mar 29, 2017 at 9:12 PM Thiago Macieira > wrote: > > On quarta-feira, 29 de mar=C3=A7o de 2017 20:41:37 PDT Vitali Lovich wrot= e: > > > It does not, so it cannot have an observable effect. > > > > doesnt it? If a function returns a Shared_ptr of a string and string_vi= ew > > that references the string, if you do: > > Can you be more specific what this function returns? "A shared_ptr of a > string > and a string_view" does not make sense, since shared_ptr only takes one > template parameter. > > I'll analyse the rest when you post your reply. > > -- > 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/3760122.IY8c= Fr858X%40tjmaciei-mobl1 > . > > --=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/CAF8PYMi%2B6VjCUvVTTvVKOCg9xTxV8mS8CLz3VpLLpqVpK= YzzhA%40mail.gmail.com. --001a113cff84817262054bf990a2 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Ah. But I forgot now that with structured binding there's a hidden= local variable anyway for the tuple itself.=C2=A0 I was thinking the compi= ler was smart and applied RVO to the individual elements directly.

On Thu, Mar 30, 2017 at 2:40 PM Vital= i Lovich <vlovich@gmail.com>= wrote:
tu= ple<shared_ptr<string>, string_view> getstr()

The 2= nd argument is a view into the string owned by shared_ptr.

The s= emantics of whether or not the string view points to owned memory depends o= n the lifetime of the shared_ptr and my understanding of what you were sayi= ng is that the lifetime changes depending on whether the get() is done or i= gnored.

On Wed, Mar 29, 2017 at 9:= 12 PM Thiago Macieira <thiago@macieira.org> wrote:
On quarta-feira, = 29 de mar=C3=A7o de 2017 20:41:37 PDT Vitali Lovich wrote:
> > It does not, so it cannot have an observable effect.
>
> doesnt it? If a function returns a Shared_ptr of a string and string_v= iew
> that references the string, if you do:

Can you be more specific what this function returns? "A shared_ptr of = a string
and a string_view" does not make sense, since shared_ptr only takes on= e
template parameter.

I'll analyse the rest when you post your reply.

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

--
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. To view this discussion on the web visit https://groups.goo= gle.com/a/isocpp.org/d/msgid/std-proposals/3760122.IY8cFr858X%40tjmaciei-mo= bl1.

--
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.
To view this discussion on the web visit h= ttps://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CAF8PYMi%2B6VjC= UvVTTvVKOCg9xTxV8mS8CLz3VpLLpqVpKYzzhA%40mail.gmail.com.
--001a113cff84817262054bf990a2-- .