From owner-sc22wg5@open-std.org Mon Dec 6 19:23:27 2010 Return-Path: X-Original-To: sc22wg5-dom8 Delivered-To: sc22wg5-dom8@www2.open-std.org Received: by www2.open-std.org (Postfix, from userid 521) id 10979C3BA1C; Mon, 6 Dec 2010 19:23:27 +0100 (CET) X-Original-To: sc22wg5@open-std.org Delivered-To: sc22wg5@open-std.org Received: from exprod6og107.obsmtp.com (exprod6og107.obsmtp.com [64.18.1.208]) by www2.open-std.org (Postfix) with ESMTP id 0721BC178E3 for ; Mon, 6 Dec 2010 19:23:24 +0100 (CET) Received: from source ([136.162.34.13]) (using TLSv1) by exprod6ob107.postini.com ([64.18.5.12]) with SMTP ID DSNKTP0qG/qwUBxcuO3WxIoql12Fn0B4m5EF@postini.com; Mon, 06 Dec 2010 10:23:25 PST Received: from fortran.us.cray.com (fortran.us.cray.com [172.31.19.200]) by stplmr01.us.cray.com (8.14.3/8.13.8/hubv2-LastChangedRevision: 12441) with ESMTP id oB6INMYr023622; Mon, 6 Dec 2010 12:23:22 -0600 Message-ID: <4CFD2A4D.6070600@cray.com> Date: Mon, 06 Dec 2010 12:24:13 -0600 From: Bill Long Reply-To: longb@cray.com Organization: Cray Inc. User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.11) Gecko/20101013 Thunderbird/3.1.5 MIME-Version: 1.0 To: fortran standards email list for J3 Cc: sc22wg5 Subject: Re: (j3.2006) (SC22WG5.4376) [ukfortran] WG5 informal ballot re Interop. TR References: <20101108175805.5B97EC178E5@www2.open-std.org> <20101206103130.1AE8AC178E3@www2.open-std.org> <20101206134148.834A7C178E4@www2.open-std.org> <4CFD0D53.8030501@cray.com> <20101206172155.862D5C178DA@www2.open-std.org> In-Reply-To: <20101206172155.862D5C178DA@www2.open-std.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-sc22wg5@open-std.org Precedence: bulk On 12/6/10 11:21 AM, Aleksandar Donev wrote: > On 12/06/10 11:20, Bill Long wrote: >> However, if it is a C function calling Fortran with such an interface, >> reconstructing all of the CLASS infrastructure on the Fortran side >> from the information in the C descriptor might be problematic. > Those are not interoperable, so there is no way for C to call such a > Fortran function, nor do we want that. The issue here is only whether I'm not sure what you mean by "those". We are defining interoperability of interfaces (not variables) here. If the interface is interoperable, it works both ways. Fortran calls C and C calls Fortran. In fact, the "C" side does not even have to be written in C. This is a fundamental feature of interoperability, spelled out in the first paragraph of Clause 15. > Fortran can pass a CLASS(*) object to C via a descriptor. It seems If we make that the case, then we have to also allow a C function to call a BIND(C) Fortran subprogram that has a CLASS(*) dummy. Note that CLASS(*) and TYPE(*) are very different in this respect. A Fortran subprogram can do almost nothing with a TYPE(*) dummy argument, so the information contained in the C descriptor is more than adequate. A Fortran subprogram can do a lot more with a CLASS(*) dummy. Cheers, Bill > Malcolm and Reinhold suggest yes, and I agree. I think Craig does too > (or he should listen to me anyway :-). > Best, > Aleks > -- Bill Long longb@cray.com Fortran Technical Support & voice: 651-605-9024 Bioinformatics Software Development fax: 651-605-9142 Cray Inc./Cray Plaza, Suite 210/380 Jackson St./St. Paul, MN 55101