220 24021 article Path: news.gmane.org!not-for-mail From: Matthew Woehlke Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: RFC: Unpacking tuples to value sequences Date: Mon, 25 Jan 2016 14:58:43 -0500 Lines: 50 Approved: news@gmane.org Message-ID: References: <6f3ece34-e302-4d95-afd0-4c1924e8a780@isocpp.org> <6ad65a24-8a2e-4053-b9c9-80d296d98e7d@isocpp.org> <72de7daf-93af-4e55-95ea-67898bd2a5f6@isocpp.org> <29e7b2a0-05fb-46e2-92bc-2a83f8a1e53c@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1453751943 7491 80.91.229.3 (25 Jan 2016 19:59:03 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 25 Jan 2016 19:59:03 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC37LBFWUIFBB674TG2QKGQEOOLJZFY@isocpp.org Mon Jan 25 20:58:54 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wm0-f70.google.com ([74.125.82.70]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1aNnHp-0005xY-1A for gclcip-std-proposals@m.gmane.org; Mon, 25 Jan 2016 20:58:53 +0100 Original-Received: by mail-wm0-f70.google.com with SMTP id b14sf22215188wmb.2 for ; Mon, 25 Jan 2016 11:58:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=to:from:subject:date:lines:message-id:references:mime-version :content-type:content-transfer-encoding:user-agent:in-reply-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=o5m8YqahmRj0XcVJ1KfmehBgackZWBtu37rET0LRUAU=; b=Z21haogEyDem5l5adn9eBlkLxUuC08d7X1ks4iqVlBOOW+HVmQFOwrQhkGmFsQIbdT qFzPXsWP6mjB37SGIO7qJDmlo2V/pznIqT3/KJWHt49kM+yHusJ9jJU3ftb1y2byIA/I uJ4T9poq3emc4bp9jUgLd3OBOSdWAZg4peeK/5BCC3PRb0hm5iUnDmrZvyImIt+iKA52 zLAlAHiacsGwoyIgd6R1kZ5wCbzS+qeHwDilRPQcG4WtQxNkNJk6Zgr9/JbjUwTNQSww iNZcwAdLIxHv0VgsicQXcjZPdBOUYorVNvv8uxVHFN36zqivuM9xmUp X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:to:from:subject:date:lines:message-id:references :mime-version:content-type:content-transfer-encoding:user-agent :in-reply-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=o5m8YqahmRj0XcVJ1KfmehBgackZWBtu37rET0LRUAU=; b=OpQ5RSXkzL0I474VHMVmTwVY/gEsTSpZ2E8dTAG+x+kJunOggBx9lsVEvigJU9QWjT e6Ky+j15bM5Vjjt5c0ugEZU/j7Pa1g02svNrtbKTheLXKr4oUjFTV1Eq+UnlOoQqhMRA HPZNQaV0b+uBM31T8Ul4JYoI2v8XYyaEKX3MfdssTu+rqFr4TEldYWnEIkIS7Wzqcj4C byqSH4iygR8sh0Dv1zuiyM+59QhXPvz8dpHFjE+WqtWX2bvpmRoXhmLVyLu2MtE5dsxo pVEcA1TmT/yH5rayaguXWs5BO0zXuJkSVeSkDIubpVWWJ7+iV0r X-Gm-Message-State: AG10YOQldRsxkML+olIpMfjN3onsqSVXraVVC4BlbF/TuyQTrWQMy8GjJZs1U03URZP7dA== X-Received: by 10.25.157.144 with SMTP id g138mr2394964lfe.5.1453751932449; Mon, 25 Jan 2016 11:58:52 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.25.21.85 with SMTP id l82ls531707lfi.3.gmail; Mon, 25 Jan 2016 11:58:51 -0800 (PST) X-Received: by 10.112.63.200 with SMTP id i8mr6889399lbs.5.1453751931174; Mon, 25 Jan 2016 11:58:51 -0800 (PST) Original-Received: from plane.gmane.org (plane.gmane.org. [80.91.229.3]) by mx.google.com with ESMTPS id mp5si10655447lbb.171.2016.01.25.11.58.51 for (version=TLS1 cipher=AES128-SHA bits=128/128); Mon, 25 Jan 2016 11:58:51 -0800 (PST) Received-SPF: pass (google.com: domain of gclcip-std-proposals@m.gmane.org designates 80.91.229.3 as permitted sender) client-ip=80.91.229.3; Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1aNnHl-0005wc-Iu for std-proposals@isocpp.org; Mon, 25 Jan 2016 20:58:49 +0100 Original-Received: from tripoint.kitware.com ([66.194.253.20]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 25 Jan 2016 20:58:49 +0100 Original-Received: from mwoehlke.floss by tripoint.kitware.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 25 Jan 2016 20:58:49 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 34 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: tripoint.kitware.com User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 In-Reply-To: X-Original-Sender: mwoehlke.floss@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of gclcip-std-proposals@m.gmane.org designates 80.91.229.3 as permitted sender) smtp.mailfrom=gclcip-std-proposals@m.gmane.org; dmarc=fail (p=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-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:24021 Archived-At: On 2016-01-25 14:37, Arthur O'Dwyer wrote: > However, there's no such "obvious" definition for [mpl::vector] std::get. >=20 > So what we're left with is: mpl::vector is "not tuple-like", but it *does= * > implement tuple_size_v and tuple_element_t. > The only part of the "tuple-like" contract that it fails to have an obvio= us > implementation for is the one part of the "tuple-like" contract *whose na= me > doesn't involve the word "tuple"*. > *That* is why the concept of "tuple-like" bothers me. LOL :-). (Note: not at you, at the observed absurdity of the situation=C2= =B9.) Thanks for explaining; I understand now. Per my earlier comment, I don't see how you would use an mpl::vector in most of the contexts in which you care about something being "tuple-like" (i.e. unpacking, conversion to/from std::tuple). Ergo, while I understand (and to an extent agree with) your concern now, I'm also thinking that it may just be one of those unfortunate facts of life. I think the problem is that we have a few related but not-quite-identical concepts, all of which are being called "tuple" (and all of which can make a reasonable argument that "tuple is the correct term, darn it"). I am open to suggestions? (Maybe we just avoid using the actual phrase "tuple-like" in the standard?) (=C2=B9 Interesting and at-least-partly applicable factoid: according to Scott Adams, laughter is sometimes a tell that you have just changed your mind on a subject.) --=20 Matthew --=20 ---=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. Visit this group at https://groups.google.com/a/isocpp.org/group/std-propos= als/. .