220 39294 article Path: news.gmane.org!.POSTED!not-for-mail From: Thomas Russell Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Standardising a type-erased iterator Date: Mon, 23 Jul 2018 01:01:24 -0700 (PDT) Lines: 23 Approved: news@gmane.org Message-ID: References: <09db196a-e818-4d7a-9af1-48f07b2f4c3d@isocpp.org> <24d8f121-aba9-4ead-b107-bc4b72014870@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_Part_7987_945385635.1532332884855" X-Trace: blaine.gmane.org 1532332761 29098 195.159.176.226 (23 Jul 2018 07:59:21 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 23 Jul 2018 07:59:21 +0000 (UTC) To: ISO C++ Standard - Future Proposals Original-X-From: std-proposals+bncBDV75LEATMKRBVMW23NAKGQEYFS3UAQ@isocpp.org Mon Jul 23 09:59:17 2018 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yb0-f197.google.com ([209.85.213.197]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fhVkS-0007TK-3v for gclcip-std-proposals@m.gmane.org; Mon, 23 Jul 2018 09:59:16 +0200 Original-Received: by mail-yb0-f197.google.com with SMTP id t14-v6sf9475600ybb.0 for ; Mon, 23 Jul 2018 01:01:27 -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=BjyKabz9dUcPLbdwcogKwRIHHaAZkjO7UUjJ7xRUqdU=; b=I//bBKy2IEvbrCGqM3v4N4r9CCbW+2kODLBnRUiYUE9/NDZIWXhVjLctxwgOlY6RBc bziSnoMJcPQlCRhvptGypswflRwNgA7ZZkdE6+WhkidLKCgwwugJEo7QNcnj1/rZqyjJ JU9X/HsyRZ9Pyi9nncWGBImXeUF2ir2jqn4GcLWyrz5VL1OCV/OB58FwNhcJFjQ4xWSL eRcUs/JHRdZNChcldpZ25M7jrGuMlZAfmCcC8JENMZNS7tocGykPS7h+UNKwkN7msSNi OaJ76R+5rDOXbQT5Dlm9mk9YWNecEEnr5XAkdi7oxaUpZ1vNVkDFBc0Vvo896x0ih5O2 TEpw== 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=BjyKabz9dUcPLbdwcogKwRIHHaAZkjO7UUjJ7xRUqdU=; b=cHTplCOp177Rnxk8mkmf0sE3iE6oD803EOB6XJfooSZC5oXaKbqj2sgS3uUJEtUlLs V2Y3ykL1otDd4UYg3AO1wCzFIenWWSMPlv5lM0QJhoM1QZ18GC0tga3DNKSk57/Vulsl 1zUAzeuxlJyNJnavyu/hQcU7rmI4v/l0X/Mh4Btfcd67WhcWw7UYLtbKLfowFwGy9Bhs GwHgv4iUwyKXttYxR81lfvmvkzy1ybK541OANNwDCs1I+f34br5a8i+vLe4oFAFQw4hD aEfk/qKjxQPbHVck+cT3lUQ+W24U3p+YWhRw1Gf0F75l918JG+l/zfLhCRqUYfHQzUd/ z3hQ== 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=BjyKabz9dUcPLbdwcogKwRIHHaAZkjO7UUjJ7xRUqdU=; b=bi5C8Nw5dgfcVxeN/cepQ5H/N9LtGqONXRmXfLzQ5/znQ4G5aEqQzXJM1wSKXDNgGg a0pniMdGk4naF3v/WDLTThVuw8N7W5OfbtcxQvh3HzwOLh/soCRNl3StDYbf8llrG4HY 4WZIshmG8JW+8770LUnMuo+B8Xa2p9326Vas3Z1GPchheL4PVKJzw+bV+evFL0qyD3RE tfm3IUZCDdRQ5vG3IcA/mVxkb4of5HVzz50WL5nEYeq8le6Sis2RURE6Jxcy66k8zVCk lQlNVnwgddMBkdUCn3X1/AhkI2blA6HRuwf/vzpibCriyvYR3dudz0BalhuxhRsQRWIG Nkdg== X-Gm-Message-State: AOUpUlFiSBoSZb5Qa6ShSnvL3uBrF90nzGvpQwwhhtjYHFTC5pnM5lS/ QpOv1kzf6xsh0mAp2ndpW8ODeg== X-Google-Smtp-Source: AAOMgpchfMv04sCmzDIS+PlchX6StaoFV2iXNntGKdz6W+SanHnoWr9IUgrwKh5tyVGo4PrtdJgEnA== X-Received: by 2002:a0d:cc03:: with SMTP id o3-v6mr3540089ywd.89.1532332886705; Mon, 23 Jul 2018 01:01:26 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 2002:a81:88c7:: with SMTP id y190-v6ls1253399ywf.28.gmail; Mon, 23 Jul 2018 01:01:25 -0700 (PDT) X-Received: by 2002:a81:78c6:: with SMTP id t189-v6mr237326ywc.7.1532332885560; Mon, 23 Jul 2018 01:01:25 -0700 (PDT) In-Reply-To: X-Original-Sender: thomas.russell97@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:39294 Archived-At: ------=_Part_7987_945385635.1532332884855 Content-Type: text/plain; charset="UTF-8" The motivation is similar to having any standard type-erased facility; it gives a concrete interface that accepts an arbitrary set of classes that conform to the required concepts. The closest existing parallel in the standard library is `std::function`, modelling the Callable concept. Having such a facility as a vocabulary type provides various benefits over function templates accepting Callables: - Reduced generated code-size (this can even go some way towards reducing the performance penalty). - Works with the OOP paradigm (virtual functions cannot be function templates) - Reduced compile-time - Can work across dynamically-linked library boundaries, providing the correctly corresponding build parameters are met. I think these are good motivations, but am interested to hear opposing opinions. -- 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/c9664ef6-f769-4942-8e44-56761d091efc%40isocpp.org. ------=_Part_7987_945385635.1532332884855-- .