From owner-sc22wg5+sc22wg5-dom8=www.open-std.org@open-std.org Thu Sep 28 19:37:16 2017 Return-Path: X-Original-To: sc22wg5-dom8 Delivered-To: sc22wg5-dom8@www.open-std.org Received: by www.open-std.org (Postfix, from userid 521) id A9BF1358A24; Thu, 28 Sep 2017 19:37:15 +0200 (CEST) Delivered-To: sc22wg5@open-std.org Received: from mail-pg0-f48.google.com (mail-pg0-f48.google.com [74.125.83.48]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by www.open-std.org (Postfix) with ESMTP id DE149356CDE for ; Thu, 28 Sep 2017 19:37:12 +0200 (CEST) Received: by mail-pg0-f48.google.com with SMTP id j70so1313160pgc.10 for ; Thu, 28 Sep 2017 10:37:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceryinstitute.org; s=google; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version; bh=ic7isVSCWd28tI4wBIb0xJkdjbLdWnkiqug5XHk0VpE=; b=RN24dPbukAuE83x16C+ugRiAkDymQDZT+BaPAUKcmQyKj+LYW+tjG9Wfr4HATS0vVr HZ/ftyCXmMRZnFNCFMNCYxRLcpuqPHopMqq5wYpao5+DoP6XyNJnHN2WjWphjXMHfrK9 7o6mr42y/DbOKk7H1vDTOUGE3owtLqyWvE/QQs380nO/0F/cnhBMdgT4jAtIEALRQ7FM 77Ap2J8kHn8ormr0lb339qfTmNlavciDfYl8qKd6kTJqNnSh4o3yoX/sPOpr5KDGopGp OT5pcxBdCB93Fiqbz0wuVS69g6rV5xfg9nrwJq4EQLhKlav7NVuvskyXu+tquhLj5q1O +5eQ== 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:cc:message-id:in-reply-to :references:subject:mime-version; bh=ic7isVSCWd28tI4wBIb0xJkdjbLdWnkiqug5XHk0VpE=; b=FRifi95k9NWloXymCU3fpCLJaMU157H7oCtuvGvhHVyZS28VfbK+lDAz5iyO8bSt1r D7/aV/dXnRUrndoA/IN4h3M/yA9mtyb3qkkO2TxytLdMb5SeGcM12N7vdVwrJwvZ0UCO FOyQ5s7dgcFhp/q+9ao/CfzeIcG+cKLjG9IQq+iGO6UYsiDDQ1+1zoTM00F6osTRFjHK DB4BTtIjL7BHfnO7nTSL7Xyo9HmLGvbeKTGaHioPNBE+llt0slsZa4SNha8B5bGxbPN4 pWszH4rug9xWwNaj0bkJGK0W7kBq40dQwmTN76WkJ7E9c0/YzUVV5py+hA9TE5dZExM0 pZbQ== X-Gm-Message-State: AHPjjUh3fnUCYt/0TJ5WVdWSTDMWPdlwFXy0PGn86SHzeWBFRO2YJWvC CwLOKPbdT1Z1PjP1Sxs9IvwInA== X-Google-Smtp-Source: AOwi7QCDsM13g/f+VFmsYqvB9ustVwBi04AvK9nIRz34zXaIjESR39kT/W17zCLiokTtbEMLc9wTbQ== X-Received: by 10.84.133.41 with SMTP id 38mr4544166plf.203.1506620231215; Thu, 28 Sep 2017 10:37:11 -0700 (PDT) Received: from localhost.mail ([50.233.164.226]) by smtp.gmail.com with ESMTPSA id i3sm3769644pgs.23.2017.09.28.10.37.09 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 28 Sep 2017 10:37:10 -0700 (PDT) Date: Thu, 28 Sep 2017 10:37:07 -0700 From: Damian Rouson To: Bill Long , fortran standards email list for J3 Cc: sc22wg5 , Van Snyder Message-ID: In-Reply-To: <20170928161910.0439E358A27@www.open-std.org> References: <20170927201113.6D137358742@www.open-std.org> <20170928020816.B2E4D358742@www.open-std.org> <20170928123430.2C442358929@www.open-std.org> <20170928161910.0439E358A27@www.open-std.org> Subject: Re: (j3.2006) (SC22WG5.5979) Generic programming examples X-Mailer: Airmail (442) MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="59cd3343_662a642c_1302" Sender: owner-sc22wg5@open-std.org Precedence: bulk --59cd3343_662a642c_1302 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On September 28, 2017 at 9:19:14 AM, Bill Long (longb=40cray.com) wrote: > On Sep 28, 2017, at 7:34 AM, Clune, Thomas L. (GS=46C-6101) wrote:=C2=A0 >=C2=A0 > Sorry - not sure how my subconscious injected the word =E2=80=9Cexcepti= ons=E2=80=9D below. I meant =E2=80=9CUsing generics/templates should not = make us lose this other =5Btype-bound procedures=5D capability.=E2=80=9D=C2= =A0 >=C2=A0 Makes more sense now.=C2=A0 A type bound procedure referenced though a polymorphic variable cannot it= self be a template because the compiler does not know what procedure is b= eing called at compile time. However, inside the specific TBP, you can ca= ll worker routines that do the actual work, and those can be written as t= emplates if that would be useful. There is a (probably small) performance= hit for the second call, but you are already making an anti-performance = decision by using the TBP path in the first place. Whether this matters t= hat much depends on how you decide to organize the code.=C2=A0 I suspect that these are some of the reasons that many in the C++ communi= ty are moving away from runtime polymorphism and inheritance and migratin= g more toward compile-time polymorphism and templates. =C2=A0Partly for t= his reason, I=E2=80=99ve been hoping to get one collaborator to join J3/W= G5 who specializes in language design, has some experience on the C++ com= mittee, has an interest in modern =46ortran, and was one of the first peo= ple to mention the aforementioned trend in C++ programming practices. =C2= =A0What Bill describes above might be a good compromise between the two p= rogramming styles. I=E2=80=99m not surprised there=E2=80=99s some tension= between the two. Damian --59cd3343_662a642c_1302 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline