220 32506 article Path: news.gmane.org!.POSTED!not-for-mail From: Zhihao Yuan Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Allow Structured Binding Outside of Variable Declaration Date: Tue, 16 May 2017 17:56:26 -0500 Lines: 98 Approved: news@gmane.org Message-ID: References: <10b21241-b683-44d5-82ce-90681b2643a4@isocpp.org> <08ff73f1-6989-393e-ee4e-8158af2e7bed@honermann.net> <20170516164245.GA16348@fukushima.lysator.liu.se> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="94eb2c14f94cdceb57054fac144d" X-Trace: blaine.gmane.org 1494975389 25647 195.159.176.226 (16 May 2017 22:56:29 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 16 May 2017 22:56:29 +0000 (UTC) To: "std-proposals@isocpp.org" Original-X-From: std-proposals+bncBCSKRWMD4EHBBHEH53EAKGQEADQQHZA@isocpp.org Wed May 17 00:56:24 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ua0-f198.google.com ([209.85.217.198]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dAlOB-0006Vg-Hz for gclcip-std-proposals@m.gmane.org; Wed, 17 May 2017 00:56:23 +0200 Original-Received: by mail-ua0-f198.google.com with SMTP id 39sf56353265uag.8 for ; Tue, 16 May 2017 15:56:29 -0700 (PDT) ARC-Seal: i=2; a=rsa-sha256; t=1494975389; cv=pass; d=google.com; s=arc-20160816; b=Sy8DGgscL4g+cAoNrl2GK63w+vVJrl4NzuCqzi2RcKBTGminqT8pfL9GRAyPGQGqeK kd8Kx3+03G9FHQuSwSQW7VZYNXz9vkLSOpsRpZYJjerlJvRDSzgGc/8nIv7C1ZpEbKr0 g3iI4wrnqymUtRiiFtud8I/l6vkpGfPqGSAAZWTlrusRUm9fncCcC63F/QwgHdQeYEUo Mgj0ewY5nocH0mjK9smkjXH1AyrMpPEI/il2VT9cJakNrljkX972mH6KDP0e4jOJPd2j NjQ0JJF6vQGbYYaAgvD95j3VpIDq9wsWOPtO3C48xRAC1EW86uvMXS7PyBO3NYMVA38t f7+Q== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-unsubscribe:list-subscribe:list-archive:list-help:list-post :list-id:mailing-list:precedence:reply-to:to:subject:message-id:date :from:references:in-reply-to:mime-version:sender :arc-authentication-results:arc-message-signature :arc-authentication-results; bh=rtW6N+LV4X0Z8rptfVe8dI2WZMyNObsfbzgEG6HhhxE=; b=pP9IzHkIBuTfLPRtukzyG4UOo/KW3u/wXCVcxx2ecP8yVC5GEDdNX318RSPANfuCdk xp/xSjzAmUU2fJCs+uQnKeDX71iJm14eZamtxYgLqd00qP6tz/7VBQvCBto7CTrZmYVL 7tCJ+BznlubG+fzAHdn8EqdBHYRx0yj9WzvqYYSGlvuvWeDdbrNTsUln34Lo7q5vgiaX 1UmNP0vRhk0ZcH8miNYa8DjwDJ5rW9PqhWnbUSL0b4YTkgOy3unYqSckOm8dzcxApY6C uWodm8GH9hL166LWqibNgCqS9pWCQ7xRnYXy7VCvEckmvFmlFQtwsybBfNQQOC97VRe6 hvAA== ARC-Authentication-Results: i=2; mx.google.com; dkim=pass header.i=@miator.net; spf=pass (google.com: domain of bounce+3f9131.69110-std-proposals=isocpp.org@miator.net designates 184.173.153.196 as permitted sender) smtp.mailfrom=bounce+3f9131.69110-std-proposals=isocpp.org@miator.net X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:mime-version:in-reply-to:references: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=rtW6N+LV4X0Z8rptfVe8dI2WZMyNObsfbzgEG6HhhxE=; b=pEOILQF82z1jkry/pySZVOlXe0NRd3fQGrYJmaHiFbvU/irkEl4fAzgEWNvR3zK/jt RZHlOQW25qlr8S8y/tDU2EKXteH/WTX3X9eyq8fUEY9ZNA036k3cCo3EboEd0mDmo+53 GzS6UtxKjrDC+S27pmLBsnWA9QFDC2DPFRcFpTzBUQbJFQQbYl+2Bwi0WbXptXJ88cO/ UVryuVyq3Qz5AbkNP/uQUlIsv7CbJQgN5rPo7J/WQkGzdVPZInUsvCjL/SuVxvapsUwg IQ06ULChH5hF1lcCIl51YegXDjOUrWsv8KPVrqEe5ErH0OTdEPOXnpazPpEui3/lPWKv xtGw== X-Gm-Message-State: AODbwcA9q2MhDk9CQkAMA+gRktsuW5iHIEs+5C+kLZ9Ce/65mk2vFypi o1AQADZXchwxMq17 X-Received: by 10.176.24.77 with SMTP id j13mr147941uag.9.1494975389039; Tue, 16 May 2017 15:56:29 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.157.37.235 with SMTP id q98ls2544031ota.49.gmail; Tue, 16 May 2017 15:56:28 -0700 (PDT) X-Received: by 10.55.221.70 with SMTP id n67mr383871qki.234.1494975388148; Tue, 16 May 2017 15:56:28 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1494975388; cv=none; d=google.com; s=arc-20160816; b=ohmcJ1wI4iysHsD5XTAMQY0IVSJTd0MbU9b1vbY7AHcuPN5J9vtFbRNXVYIoAqM9bv yy07G+E58vXh7sizm48cxNVfWY0bSEsrj8V0tT09Zmt/Bi1cN+TYeHgjsllOMeOVTOW2 LneKGjN9aaCH4iPsKI4DAWdXzsMoCCsgFMTqUtozgr52vvlTsnw5AZ9Is/UxML7C2vtx afv55uonZ693taWRHKuQWDGGKv9UBpivukU8ynVfhHTt0i6u2NHLk6N44zvQvkTQe3NQ iR68uYMc3ExGAuCeJ7jodW5hv5zbcMysi+Av4VpnJ5Tw8c8vAaMUGUwE6wueKNR6I2ro Xr7g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=to:subject:message-id:date:from:references:in-reply-to:mime-version :sender:domainkey-signature:dkim-signature :arc-authentication-results; bh=m5uuJRQgEJGMqAmY6H8LPcmv25ZkTfqFE5y+cik3XLE=; b=wS7iI1xzqJwL4FBVU9p3YgwBFoZ2R/4lhxd9B4Rb37yQW4X0iWi/kLN1iVJpI3316o J4U2Es2dfjRcXqPQt+fT7QpHBRB2Ml7+bgXW8W2pnBN+mbLOqd8fj8x1n1FZa/cMuz8X 32hib7Qy8+pTycNLj/2PBF3q/fYqZuvlo+1iT3GydVeaRV7yV5F53sDdjt5e4a6LnqGP QCKVnHTF80lDjeDlYYxI+V7ccZW+AFaqg4KdjSz+njoDLXXlZrBhhxhvi5h0QYahcO3v 5BlWFFCRQ/Ee8Gm+pqJjuPlPvj4dYlPb6FzXaGIF6EU0N/wMRPP0DUrf3v9Lpv944blx SdJA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@miator.net; spf=pass (google.com: domain of bounce+3f9131.69110-std-proposals=isocpp.org@miator.net designates 184.173.153.196 as permitted sender) smtp.mailfrom=bounce+3f9131.69110-std-proposals=isocpp.org@miator.net Original-Received: from mail-s68.mailgun.info (mail-s68.mailgun.info. [184.173.153.196]) by mx.google.com with UTF8SMTPS id m41si210416qtc.237.2017.05.16.15.56.28 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 16 May 2017 15:56:28 -0700 (PDT) Received-SPF: pass (google.com: domain of bounce+3f9131.69110-std-proposals=isocpp.org@miator.net designates 184.173.153.196 as permitted sender) client-ip=184.173.153.196; Original-Sender: zy@miator.net X-Mailgun-Sending-Ip: 184.173.153.196 X-Mailgun-Sid: WyI3MTBkYiIsICJzdGQtcHJvcG9zYWxzQGlzb2NwcC5vcmciLCAiNjkxMTAiXQ== Original-Received: from mail-pf0-f176.google.com (mail-pf0-f176.google.com [209.85.192.176]) by mxa.mailgun.org with ESMTP id 591b839b.7fda240d1130-smtp-out-n02; Tue, 16 May 2017 22:56:27 -0000 (UTC) Original-Received: by mail-pf0-f176.google.com with SMTP id n23so82432799pfb.2 for ; Tue, 16 May 2017 15:56:27 -0700 (PDT) X-Received: by 10.99.109.73 with SMTP id i70mr426594pgc.62.1494975386543; Tue, 16 May 2017 15:56:26 -0700 (PDT) Original-Received: by 10.100.151.71 with HTTP; Tue, 16 May 2017 15:56:26 -0700 (PDT) In-Reply-To: X-Gmail-Original-Message-ID: X-Original-Sender: zy@miator.net X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@miator.net; spf=pass (google.com: domain of bounce+3f9131.69110-std-proposals=isocpp.org@miator.net designates 184.173.153.196 as permitted sender) smtp.mailfrom=bounce+3f9131.69110-std-proposals=isocpp.org@miator.net 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:32506 Archived-At: --94eb2c14f94cdceb57054fac144d Content-Type: text/plain; charset="UTF-8" On Tue, May 16, 2017 at 5:49 PM, Ville Voutilainen < ville.voutilainen@gmail.com> wrote: > >> > for (TupleLike [x, y] : something) { ... } > >> > > >> > Where TupleLike is a concept. > >> > >> How does that help me specify the concrete types of the bindings? > > > > > > It does type-check, as same as you putting > > > > static_assert(is_same_v); > > > > in the loop. > > > > But it doesn't change the type object of the > > underlying object, or the type of the bindings. > > I need to use some weird concept to check that the type of x is A? If constrained-type-specifier is accepted as-is, I bet people will have more creative ways to overuse it. However, if that can restore our energy spent on inventing new syntax, maybe I can give a "meh"... -- Zhihao Yuan, ID lichray The best way to predict the future is to invent it. _______________________________________________ -- 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/CAGsORuCq3%2BKhQjp7ARb8fvjaROAEEFP45geKENkPg3C_trmT%3Dg%40mail.gmail.com. --94eb2c14f94cdceb57054fac144d Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

On Tue, May 16, 2017 at 5:49 PM, Ville Voutilainen <ville.voutilainen@gmail.com> wrote:
>> >=C2=A0 =C2=A0for (TupleLike<A, B> [x= , y] : something) { ... }
>> >
>> > Where TupleLike is a concept.
>>
>> How does that help me specify the concrete types of the bindings?<= br> >
>
> It does type-check, as same as you putting
>
>=C2=A0 =C2=A0static_assert(is_same_v<decltype(x), A>);
>
> in the loop.
>
> But it doesn't change the type object of the
> underlying object, or the type of the bindings.

I need to use some weird concept to check that the type of x is A?

If constrained-type-specifier is accepted as-is,= I bet
people will have more creative ways to overuse it.
However, if that can restore our energy spent on
inventing new sy= ntax, maybe I can give a "meh"...

--
Zhihao Yuan, ID lichray
The best way to= predict the future is to invent it.
______________________________= _________________

--
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 https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CAGsORuCq3%2B= KhQjp7ARb8fvjaROAEEFP45geKENkPg3C_trmT%3Dg%40mail.gmail.com.
--94eb2c14f94cdceb57054fac144d-- .