220 28289 <7484c940-1c69-7223-c83d-da89e6b87cbb@rrsd.com> article Path: news.gmane.org!.POSTED!not-for-mail From: Robert Ramey Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: what makes a Concept a Concept? 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[23.83.214.30]) by mx.google.com with ESMTPS id l14si31128992pfi.217.2016.09.18.19.35.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 18 Sep 2016 19:35:10 -0700 (PDT) Received-SPF: pass (google.com: domain of ramey@rrsd.com designates 23.83.214.30 as permitted sender) client-ip=23.83.214.30; X-Sender-Id: wwwh|x-authuser|ramey@rrsd.com Original-Received: from relay.mailchannels.net (localhost [127.0.0.1]) by relay.mailchannels.net (Postfix) with ESMTP id B3361100C14 for ; Mon, 19 Sep 2016 02:35:09 +0000 (UTC) Original-Received: from clippers.accountservergroup.com (ip-10-229-2-62.us-west-2.compute.internal [10.229.2.62]) by relay.mailchannels.net (Postfix) with ESMTPA id 15990100179 for ; Mon, 19 Sep 2016 02:35:09 +0000 (UTC) X-Sender-Id: wwwh|x-authuser|ramey@rrsd.com Original-Received: from clippers.accountservergroup.com ([UNAVAILABLE]. [10.107.128.240]) (using TLSv1 with cipher DHE-RSA-AES256-SHA) by 0.0.0.0:2500 (trex/5.7.8); Mon, 19 Sep 2016 02:35:09 +0000 X-MC-Relay: Neutral X-MailChannels-SenderId: wwwh|x-authuser|ramey@rrsd.com X-MailChannels-Auth-Id: wwwh X-MC-Loop-Signature: 1474252509242:2468538331 X-MC-Ingress-Time: 1474252509241 Original-Received: from 207-170-229-104.static.twtelecom.net ([207.170.229.104]:42424 helo=MacBook-Pro.local) by clippers.accountservergroup.com with esmtpsa (TLSv1:DHE-RSA-AES128-SHA:128) (Exim 4.87) (envelope-from ) id 1bloQG-0009Wi-FF for std-proposals@isocpp.org; Sun, 18 Sep 2016 19:35:08 -0700 In-Reply-To: <1fc1c369-a709-41b0-bcd6-5fc01e814a5a@isocpp.org> X-AuthUser: ramey@rrsd.com X-Original-Sender: ramey@rrsd.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of ramey@rrsd.com designates 23.83.214.30 as permitted sender) smtp.mailfrom=ramey@rrsd.com 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:28289 Archived-At: On 9/18/16 3:05 PM, najjarchedy@gmail.com wrote: > > i started writing an article/documentation about Concepts by at a point > in time when i started giving examples and saying if this is a Concept > or a simple Constraint, i found my self enable to answer the question > why this is a concept ? > according to CPPCoreGuideline example :Addable is not a Concept because > it violates the Commutativity property of Addition.that's okay, but what > makes EquallyComparable or Regular a Concept? > > Addable is defined like so: > This has been bugging me for years. Concept is a very ill chosen word to describe what it is and has lead to much confusion and made the "concept" exceedingly difficult to understand. When every you see the word "Concept" in the context of C++ types mentally substitute the words "Type Requirements". This will clarify things immensely. Now define type requirements as the list of legal expressions which may include the type in question. It's that simple. Of course this opens the way to abominations like "Sortable". Before anyone asks, the definition of "Sortable" would be: a type T is "Sortable" if, when placed in a suitable container, the container can be sorted..., which obviously make no sense. Robert Ramey -- 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. 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