220 33176 <74994441.Y8ukuuY6jn@tjmaciei-mobl1> article Path: news.gmane.org!.POSTED!not-for-mail From: Thiago Macieira Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Add a few missing things from the iterator library Date: Tue, 11 Jul 2017 23:27:43 -0700 Lines: 62 Approved: news@gmane.org Message-ID: <74994441.Y8ukuuY6jn@tjmaciei-mobl1> References: <6e2d133b-1c0a-49a9-ae2b-98d82d3a40d3@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Trace: blaine.gmane.org 1499840867 1434 195.159.176.226 (12 Jul 2017 06:27:47 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Wed, 12 Jul 2017 06:27:47 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCB4TK757YBRBYUCS7FQKGQEKDNL3VY@isocpp.org Wed Jul 12 08:27:43 2017 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wr0-f200.google.com ([209.85.128.200]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1dVB7e-00005J-SU for gclcip-std-proposals@m.gmane.org; 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[2a01:4f8:d13:f81:21c:14ff:fe01:12a3]) by mx.google.com with ESMTP id g204si1353396wma.58.2017.07.11.23.27.46 for ; Tue, 11 Jul 2017 23:27:46 -0700 (PDT) Received-SPF: pass (google.com: domain of thiago@macieira.org designates 2a01:4f8:d13:f81:21c:14ff:fe01:12a3 as permitted sender) client-ip=2a01:4f8:d13:f81:21c:14ff:fe01:12a3; Original-Received: from tjmaciei-mobl1.localnet (unknown [IPv6:2601:1c0:4501:5f9f:95eb:2c54:99bc:1ab]) by gondolin.macieira.info (Postfix) with ESMTPSA id 97B4411A817 for ; Tue, 11 Jul 2017 23:27:45 -0700 (PDT) In-Reply-To: X-Original-Sender: thiago@macieira.org X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of thiago@macieira.org designates 2a01:4f8:d13:f81:21c:14ff:fe01:12a3 as permitted sender) smtp.mailfrom=thiago@macieira.org 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:33176 Archived-At: On ter=C3=A7a-feira, 11 de julho de 2017 13:09:09 PDT Giovanni Funchal wrot= e: > Thanks Thiago, Nicol, those are some very good points and I now think lik= e > you that (3) was a bad idea, but I still think proposals (1) and (2) migh= t > make sense to propose as additions. Why? What value does it give? > > Just try: > This works: >=20 > void f(std::unordered_map::const_iterator) {} > void g(std::unordered_map::iterator it) > { > f(static_cast::const_iterator>(it)); > } Sorry, that is not what I meant. Let me rewrite: void f(std::unordered_map::const_iterator) {} template void g(ForwardIterator it) { f(std::make_const(it)); } void h() { std::unordered_map m; g(m.begin()); } Please write std::make_const such that the code above works. > Granted it is not trivial to implement std::make_const_iterator so that i= t > deduces the type to cast to, but I think disregarding implementation for > one second that this just points out how useful this feature would be if > g() needed a const_iterator for whatever reason, exactly because a > const_iterator is not a const iterator. Please give us a couple of those "whatever reasons". Let's say at least 5= =20 distinct use-cases. --=20 Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org Software Architect - Intel Open Source Technology Center --=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/74994441.Y8ukuuY6jn%40tjmaciei-mobl1. .