220 38459 <3eaf8f38-0284-424b-9dc8-10db869fdb69@isocpp.org> article Path: news.gmane.org!.POSTED!not-for-mail From: Omer Rosler Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Concepts fragmentation problem Date: Sun, 3 Jun 2018 09:48:08 -0700 (PDT) Lines: 55 Approved: news@gmane.org Message-ID: <3eaf8f38-0284-424b-9dc8-10db869fdb69@isocpp.org> References: Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_23003_970630986.1528044488303" X-Trace: blaine.gmane.org 1528044364 17324 195.159.176.226 (3 Jun 2018 16:46:04 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 3 Jun 2018 16:46:04 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBC2L3NWCRYJBBSNX2DMAKGQE2V4GQUI@isocpp.org Sun Jun 03 18:46:00 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yw0-f199.google.com ([209.85.161.199]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fPW8l-0004O0-BE for gclcip-std-proposals@m.gmane.org; Sun, 03 Jun 2018 18:45:59 +0200 Original-Received: by mail-yw0-f199.google.com with SMTP id n201-v6sf10292715ywd.17 for ; Sun, 03 Jun 2018 09:48:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=RUM7rIAbTGSGnOCwYdVugfk0iip8zKdfhdH6MH7eEGI=; b=H33b+kjr2EwQvrZsSZE1o57jf+lbza62nVY9BPbcybhHt/4F8a1uIOQjBEo1QTr6p2 p+mzKIBvWW81HXagHEaEYYGQ2xEa63OeKkprK29SzedcNEj3w4LPN+kgvm2glBwm3HpD 8dJyatBrx6rr4MbOfeDqPJa0n51Yithr7jTAuLemzZV44BMm0yT3r/ABsBX/iANgDALw AUIhtPvFqAXpK0xhf6Xtij6UGb/lGBRF/TXdUKg5yqtp95Cpau5DD9tj+eIG//pK9DgQ 1RD0MHXG5PmymT/97Q5H0Pf/zaXqK555PUFoDJbaGuN/5OkIG/Yag4BqhvDghjS8RSYN dAsg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:message-id:in-reply-to:references:subject:mime-version :x-original-sender:reply-to:precedence:mailing-list:list-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe; bh=RUM7rIAbTGSGnOCwYdVugfk0iip8zKdfhdH6MH7eEGI=; b=JPLs9kW9451vOBwRFkqOCePEA5EkQdSGIkMkP5LZBKPMlyIw0EvtVR3L9ANatiEjA+ aT5CMHyhGMmFTc7s4wGeMDLeNeahQeUmis37DlsUwDutPTbuKCXb3NhY9EE5RA63/qx8 nxGTmZrPnfl8QmzAGC5K0aSbXjkl/F8A8BUyANQmvTB0jCX9H47b5TeJD7LCuTGGuXPg 2+TExu3tDnF/V6otBgUPWVLY1BQHq7igUzk7kfpgeN7uNP0J+IncIM/lnDX+TZZLzAcH 5GxEif9pomplVNB7B+K9nSJSj8pHkfoitvXVvq854GReZFjqYtNIWkfgnVPXOM5sTEv1 N0GA== 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:in-reply-to:references :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=RUM7rIAbTGSGnOCwYdVugfk0iip8zKdfhdH6MH7eEGI=; b=bIwXlfXZgOb96cUTdRh1JHshPWi0ryIFAMVosWj48uqKxP8xIs7qtE0QOH8AFMTH/t HTlDYAaixPqc1bFrH816DU3VWBDjenftkvMScEQqFsh/LCu87FXJHNiCpyHRQpcsz5DM gGeVkifQL4UUdvuhC9LuZUbdfFzpA8d4OzSf2JFxzOfjC/4gPuQvRwayzqLG0cmIwJrT JD+UK46IQpioIB/aib2ci2IZB4ooOgNutVsx1fmcyFBLWkFKJXGzR/eKWB5CFfsrBzcC SWx0faKsG2ZiE1aUG9ddC5cW3C2/1BAmr0O0h+9LGrCRk52nkYOjic4TyTrcZ3kftrGO 7NZA== X-Gm-Message-State: ALKqPwdax/pyrcBpvVNfEOxZhbzyLEYMWfeiZ1XQNLCgDZGAq5wIfeLX jfFpOy0I4wbThRDrFfhzuOWpDw== X-Google-Smtp-Source: ADUXVKJ17AVhMNLe07EAlj7AXBjYYakEEfyN1HmF15FkZ8/mmkc/+HG766BbbNK6c0U1ml59HaTClg== X-Received: by 2002:a81:5ac2:: with SMTP id o185-v6mr5675532ywb.35.1528044490172; Sun, 03 Jun 2018 09:48:10 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 2002:a81:a881:: with SMTP id f123-v6ls4949859ywh.2.gmail; Sun, 03 Jun 2018 09:48:09 -0700 (PDT) X-Received: by 2002:a81:9a4f:: with SMTP id r76-v6mr757199ywg.0.1528044488819; Sun, 03 Jun 2018 09:48:08 -0700 (PDT) In-Reply-To: X-Original-Sender: omer.rosler@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:38459 Archived-At: ------=_Part_23003_970630986.1528044488303 Content-Type: text/plain; charset="UTF-8" On Sunday, June 3, 2018 at 4:21:19 AM UTC+3, Jake Arkinstall wrote: > On Sun, 3 Jun 2018, 00:57 Omer Rosler wrote: > > This is a question/issue I have stumbled upon while trying out the concepts TS, I hope this is the right forum. > > > > This kind of thing is well suited here. Although this is generally for bringing an idea to a proposal worthy state, critiques of current proposals and problems with accepted proposals are common and welcome. > > > "Here is the problem: The concept users need to implement (if they use the adaptor) is not properly defined." > > > Can you elaborate on this problem you describe with a further code sample? Something a little more concrete to work with - I got a little lost trying to understand your conclusion. Think of a node library that abstracts away both memory access and connections between the nodes: `template concept DAGNode = requires { typename T::children_router_type; T T::get_child(children_router_type child_connection); }; ` Now for a much more specific concepts - that of a binary tree node: ` enum binary_node_connections { left, right }; template concept BinaryTreeNode = requires { requires std::is_same_v; T get_right(); T get_left(); }; ` The interface that is exposed by the concept is supposed to be getting nodes by the specific functions - get_right and get_left The default implementation of `get_child` using those methods can be given by a CRTP base, but then for node classes implementors this is a whole new concept to implement. This is the underlying problem, especially if every concept does that. For example we might add traversal requirement for any `DAGNode` or add a `BinarySearchTreeNode` for balanced trees that adds a search member function, etc etc. This doubles the number of concepts. And completely separates users from implementers. -- 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/3eaf8f38-0284-424b-9dc8-10db869fdb69%40isocpp.org. ------=_Part_23003_970630986.1528044488303-- .