220 37073 <93e7e509-edf0-4df6-9b2f-555bba92a04a@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: bastienpenava@gmail.com Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: specify concept implementation Date: Mon, 26 Feb 2018 08:11:04 -0800 (PST) Lines: 106 Approved: news@gmane.org Message-ID: <93e7e509-edf0-4df6-9b2f-555bba92a04a@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_14543_1306320811.1519661464926" X-Trace: blaine.gmane.org 1519661347 22102 195.159.176.226 (26 Feb 2018 16:09:07 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 26 Feb 2018 16:09:07 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBCG3XHNI6IDRBGPD2DKAKGQER5DBDFI@isocpp.org Mon Feb 26 17:09:03 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ua0-f197.google.com ([209.85.217.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1eqLKn-0005BD-AZ for gclcip-std-proposals@m.gmane.org; Mon, 26 Feb 2018 17:09:01 +0100 Original-Received: by mail-ua0-f197.google.com with SMTP id g9sf10130370ual.8 for ; Mon, 26 Feb 2018 08:11:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:subject:mime-version:x-original-sender :reply-to:precedence:mailing-list:list-id:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=PQfbXpqjR1WbXghh2Fr7ReZkmZXMuOeNfHjUzx+Or1E=; b=XZ8DlI77WHHYh12jz2N9Ed9/+xMGBMVp6jv/wIGg9A5sccYhQ+3I86R849iD7B/GW9 RWBTWvvCABSklNLvi0nuQIxJ3lbEOHPF+TQZyvjmzaIO5y5cGNy0LrZL46Y6jSmQjpot f9UPcPGX/T/SEHKFYSbNsa4V5/5T80YcR/y5k6hTHolXVgJt/1H3Knb/XkJeZuafNPR8 +JbWp9Lb0wkZYn/jk+YhtipAO0gIPBwbr2I8nL1MQvqkbqWGUnNieKqd1LMCJW/Icc/f ux00QfKgUsLKFvRjKl1XUGrf60P4DeJSwMYSQndgZjGOdAxHSTVhSGgzY2XWjXKqhLIg Ouyg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id:subject:mime-version:x-original-sender :reply-to:precedence:mailing-list:list-id:list-post:list-help :list-archive:list-subscribe:list-unsubscribe; bh=PQfbXpqjR1WbXghh2Fr7ReZkmZXMuOeNfHjUzx+Or1E=; b=egLBatiT//EvdQQEhdtbxPxeKcsrhJ4/Ea9fE7WY7lkwB6ts2QlMIWtLkGVDwNKB4R zD6+J4f3il/BaU36JewiS2CG0/Jl0ZlppiJAZgQhxUpYVvIMQYLP0Dd5W347L/4CsoY6 D4N8jM3p9kNWhkkK8tQPzrKZrk0hOLU245EzflWl3OCmmG4NBBGq7CKLp/3DN6uVbUjI tdVWl2z2/Gq/Aesm/x5JcHOgKGLehczJK8P5UfLs0Jlkhk0HsefHVFIWLUCJM8DxHejI pqq+SFCthyzinaSLltvENnbwNotXapZOdW7Xeqp5nS47GRac2csPMpGoF9cqYxaKNHn4 3Cwg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:message-id:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=PQfbXpqjR1WbXghh2Fr7ReZkmZXMuOeNfHjUzx+Or1E=; b=kFKwJtDcaqRxM+iaVbd9DxjEZRVeZfXu8ScwZ8sUfu/yQzwWJ9gM6fkyEXpkYiDeTn S67yJHwkFa4Z3S/azyUQxDTQ37uce+ZtBbSCt5xym64K/n9z6KLHCUHuutHbZEYWOY83 lMSa1nIrt9ydbA9zNz9jjQpdXpQkCkA2jWtsSjR6bDC2oQsQlPx9c0NGejJNCTtnG3Xi pYhRPWqNXO5cqQNY8wPE/kokdMdR02M8anIuEw7/1clwnXouyR/6tifv4sZZEWKn11lA 9yeWI0xn9ElNLA9r4W+TpfWBH71itvklckQACVcZaxcMt4Pkui5zqHwR/bYc9L6P5RKr BH/w== X-Gm-Message-State: APf1xPAS9pq3uRkuO+ea10fvR73mwqdLp0Y2UMuDnMgrvvkUI8hfweUU rDZspYYtZjK+GkW2yNv61Ytgig== X-Google-Smtp-Source: AG47ELu3yLkN7IwpwuuADLxPzWLwKBpPgIxB/Lv+qjLUlU2RA6GQ3vrJlVn09RO0mXDr4a2daWVF5A== X-Received: by 10.159.38.101 with SMTP id 92mr3781679uag.15.1519661467421; Mon, 26 Feb 2018 08:11:07 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.31.238.201 with SMTP id m192ls5189167vkh.1.gmail; Mon, 26 Feb 2018 08:11:05 -0800 (PST) X-Received: by 10.31.162.130 with SMTP id l124mr63528vke.0.1519661465450; Mon, 26 Feb 2018 08:11:05 -0800 (PST) X-Original-Sender: BastienPenava@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:37073 Archived-At: ------=_Part_14543_1306320811.1519661464926 Content-Type: multipart/alternative; boundary="----=_Part_14544_117551217.1519661464926" ------=_Part_14544_117551217.1519661464926 Content-Type: text/plain; charset="UTF-8" Hi, I believe it would be interesting to allow the users to state, when declaring a type, that he aims at implementing a specific concept. template concept ValueType = requires() { T::value; } struct A : concept C { }; //once the type has been instantiated check that the concepts are valid with the new type. //error: A doesn't satisfy the C concept. No A::value I believe it would render the code easier to read by making explicit the intent of the writer. It would also make debugging easier in case of an error when writing an implementation of a concept and could be useful if/when the definition of a concept changed. -- 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/93e7e509-edf0-4df6-9b2f-555bba92a04a%40isocpp.org. ------=_Part_14544_117551217.1519661464926 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hi,

I believe it would be interesting t= o allow the users to state, when declaring a type, that he aims at implemen= ting a specific concept.

template<class T>
= concept ValueType =3D requires() { T::value= ; <= span style=3D"color: #660;" class=3D"styled-by-prettify">}

struct A : concept C
{
};

//once the typ= e has been instantiated check that the concepts are valid with the new type.
//error: A doesn't sa= tisfy the C concept. No A::value

I= believe it would render the code easier to read by making explicit the int= ent of the writer.
It would also make debugging easier in case of= an error when writing an implementation of a concept and
could b= e useful if/when the definition of a concept changed.

--
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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/93e7e509-edf0-4df6-9b2f-555bba92a04a= %40isocpp.org.
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