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,FREEMAIL_FROM
	autolearn=ham autolearn_force=no version=3.4.4
X-Google-Thread: 103376,dc678c047f29ac37
X-Google-Attributes: gid103376,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!news4.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!newsfeed00.sul.t-online.de!t-online.de!130.59.10.21.MISMATCH!kanaga.switch.ch!switch.ch!news.in2p3.fr!in2p3.fr!proxad.net!cleanfeed1-a.proxad.net!nnrp2-2.free.fr!not-for-mail
Message-ID: <446f31eb$0$6996$626a54ce@news.free.fr>
From: Yves Bailly <kafka.fr@laposte.net>
Subject: Re: C++ from Ada, again
Newsgroups: comp.lang.ada
Date: Sat, 20 May 2006 17:12:42 +0200
References: <446cee4e$0$5159$626a54ce@news.free.fr>
User-Agent: KNode/0.10.2
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7Bit
Organization: Guest of ProXad - France
NNTP-Posting-Date: 20 May 2006 17:12:43 MEST
NNTP-Posting-Host: 81.56.171.53
X-Trace: 1148137963 nnrp2-2.free.fr 6996 81.56.171.53:54567
X-Complaints-To: abuse@proxad.net
Xref: g2news2.google.com comp.lang.ada:4314
Date: 2006-05-20T17:12:43+02:00
List-Id: <comp.lang.ada>

Hello all,

I've refined my last try to call C++ from Ada. Grab it there:
http://kafka-fr.hd.free.fr/~yves/cpp_from_ada.tar.bz2

Now memory is dynamically allocated, which I wanted to avoid. But
I didn't find another way to keep the inheritance semantic. So basically,
given a C++ class "Base" and a derived class "Derived":

class Base 
{ ... };
class Derived: public Base 
{ ... };

...now you keep this model into Ada:

type Base is tagged ... -- details omitted here
type Derived is new Base with ... -- details omitted here

So the C++ hierarchy is reflected in Ada.

If you create new derived type into Ada, overriding virtual methods,
the dispatching occures as you would expect. More precisely, the C++
class contains:

class Base
{ public:
    void method()
    { 
       // calls the virtual method
       virtual_method(); 
    }
    virtual void virtual_method()
    { /* ...something...*/ }
};
(actually the code contains many std::cout to keep track of the flow)

This is translated in Ada by:

type Base is tagged ... -- details omitted here
not overriding procedure Method(b: in Base'Class);
not overriding procedure Virtual_Method(b: in Base);

Now suppose you derive from Base:

type Sub is new Base with null record;
overriding procedure Virtual_Method(s: in Sub);

Then create an instance:
s: Sub;

...when you invoke Method(s), the Virtual_Method() called is the
overriden one.

I tried to avoid as much as possible any compiler- or platform-specific
features. However I don't have access to anything else than Gnat and
a Linux/i386 platform. Thanks to point me anything not portable.

Any comments welcome ! I'm not that experienced in those things...

Best regards,

-- 
(o< | Yves Bailly  : http://kafka-fr.net   | -o)
//\ | Linux Dijon  : http://www.coagul.org | //\
\_/ |                                      | \_/`