220 21312 article Path: news.gmane.org!not-for-mail From: Sean Middleditch Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: missing hash_code result in P0029 Date: Mon, 5 Oct 2015 13:18:17 -0700 Lines: 33 Approved: news@gmane.org Message-ID: References: <1572715.jJmjmrJA0J@tjmaciei-mobl4> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1444076301 26739 80.91.229.3 (5 Oct 2015 20:18:21 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 5 Oct 2015 20:18:21 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCDODCNR2QPRBCVWZOYAKGQEFSKJKOY@isocpp.org Mon Oct 05 22:18:20 2015 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-la0-f72.google.com ([209.85.215.72]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZjCDD-0006E6-MY for gclcip-std-proposals@m.gmane.org; Mon, 05 Oct 2015 22:18:19 +0200 Original-Received: by lana8 with SMTP id a8sf42078022lan.1 for ; Mon, 05 Oct 2015 13:18:19 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:sender:in-reply-to:references:date :message-id:subject:from:to:content-type: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=VEAao/LSf+v+7KBMRLyJBpAEFgeipMXTQxWu7CG+j7U=; b=BD6ngbjocEfIFeOyb/1nFd4NstpLOd36ogm6U89m9+q7Eh/Y9budA4VgYMXMO5pPk/ rM0VzSIa2xCrwzKSYWmF29UJA0cCl6I6XeIhGMgxy3KARCV/Pkg1LHWm36kDD4q5SP6R y/5/6tdqgR95kAUj/7WwXnT2P50pANhIlgW3P9q0sd4g2SDrCQckLYva+DvLd4DxS/TB rl0LF1JuS+CUkJS/4Z6xOyyhYAZXqLDHpMC+VOdp+qDo2pZ9bPp656uGU9cDOIPSE5rw nE6PIE3KgRk7vnKGhsR0akCvcHtq30i1BvHvj1EAoIlDZp4ItxWo7ztQTmHxgbxF9k8s x0tA== X-Gm-Message-State: ALoCoQkB9OeGIjX1Pf5uYrsAWDIXTH5Eyq+pT5ChQCl2Seu8pLkWvrV0ybuNzBr2+chvw5h0gEKf X-Received: by 10.180.10.202 with SMTP id k10mr2813755wib.2.1444076299379; Mon, 05 Oct 2015 13:18:19 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.180.211.50 with SMTP id mz18ls928640wic.25.canary; Mon, 05 Oct 2015 13:18:18 -0700 (PDT) X-Received: by 10.180.198.109 with SMTP id jb13mr13746699wic.17.1444076298430; Mon, 05 Oct 2015 13:18:18 -0700 (PDT) Original-Received: from mail-wi0-x236.google.com (mail-wi0-x236.google.com. [2a00:1450:400c:c05::236]) by mx.google.com with ESMTPS id er8si33213706wjc.65.2015.10.05.13.18.18 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 05 Oct 2015 13:18:18 -0700 (PDT) Received-SPF: pass (google.com: domain of sean.middleditch@gmail.com designates 2a00:1450:400c:c05::236 as permitted sender) client-ip=2a00:1450:400c:c05::236; Original-Received: by wiclk2 with SMTP id lk2so130996524wic.1 for ; Mon, 05 Oct 2015 13:18:18 -0700 (PDT) X-Received: by 10.194.62.20 with SMTP id u20mr37542799wjr.2.1444076297878; Mon, 05 Oct 2015 13:18:17 -0700 (PDT) Original-Sender: sean.middleditch@gmail.com Original-Received: by 10.27.14.72 with HTTP; Mon, 5 Oct 2015 13:18:17 -0700 (PDT) In-Reply-To: X-Original-Sender: sean@middleditch.us X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of sean.middleditch@gmail.com designates 2a00:1450:400c:c05::236 as permitted sender) smtp.mailfrom=sean.middleditch@gmail.com; dkim=pass header.i=@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org 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:21312 Archived-At: On Mon, Oct 5, 2015 at 10:34 AM, Shahms King wrote: > You can trivially use them in your own hashing container, as you would now. > The primary thing that is being changed is the mechanism by which > user-defined types can supply their data to the hash function, not the > interface for retrieving final values from that hash function. The > high-level API for retrieving a hash value from an object is unchanged, e.g. Gotcha. In that case, this proposal is less complete than N3980 was. The HashAlgorithm uhash<> interfaces were more widely usable. With P0029, users have to write extraneous high-level wrappers around their algorithms (a std::hash replacement), and generic code that needs to support generic progressive hashes is left without a solution. It seems to me a near trivial addition to require HashCode to have a result_type and a conversion operator/method to result_type. It will still satisfy all the goals of P0029 while also satisfy requirements covered by N3980, no? Is there a significant cost/risk of adding such an interface to the HashCode concept? -- Sean Middleditch http://seanmiddleditch.com -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. 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