From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Thread: 103376,fd173879a595bde X-Google-Attributes: gid103376,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news4.google.com!newshub.sdsu.edu!elnk-nf2-pas!elnk-pas-nf1!newsfeed.earthlink.net!stamper.news.pas.earthlink.net!newsread3.news.pas.earthlink.net.POSTED!a6202946!not-for-mail From: "Jeffrey R. Carter" Organization: jrcarter at acm dot org User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.12) Gecko/20050915 X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: pragma convention References: <87y8435fve.fsf@code-hal.de> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Message-ID: Date: Sun, 06 Nov 2005 01:07:20 GMT NNTP-Posting-Host: 67.3.218.158 X-Complaints-To: abuse@earthlink.net X-Trace: newsread3.news.pas.earthlink.net 1131239240 67.3.218.158 (Sat, 05 Nov 2005 17:07:20 PST) NNTP-Posting-Date: Sat, 05 Nov 2005 17:07:20 PST Xref: g2news1.google.com comp.lang.ada:6249 Date: 2005-11-06T01:07:20+00:00 List-Id: Anonymous Coward wrote: > You raise a good point, assuming C compilers all have the freedom to > represent types arbitrarily. So what's the point of the current > existence of pragma Convention? What can I expect pragma convention > to do for me? pragma Convention (X, ... really means the convention used by some specific X compiler chosen by the Ada compiler developers for those cases where the X language does not rigorously specify the characteristic in question. Convention C does do certain common things for you. For an access type, you insure that it is just a pointer, and doesn't contain any additional data (which Ada's access values can and sometimes do contain). For subprograms, you get automatic conversion of parameters to pointers to match C passing rules and make [in] out parameters work properly. This latter is very useful; you can write procedure C (X : out Interfaces.C.Int); pragma Import (C, X, "xInC"); and the compiler takes care of passing a pointer for you. -- Jeff Carter "Perfidious English mouse-dropping hoarders." Monty Python & the Holy Grail 10