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-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,c13882a1aeb96bdb
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2003-06-04 07:09:15 PST
Path: archiver1.google.com!postnews1.google.com!not-for-mail
From: mheaney@on2.com (Matthew Heaney)
Newsgroups: comp.lang.ada
Subject: Re: linking to C++
Date: 4 Jun 2003 07:09:14 -0700
Organization: http://groups.google.com/
Message-ID: <1ec946d1.0306040609.60873482@posting.google.com>
References: <3eddb5dd$1@baen1673807.greenlnk.net>
NNTP-Posting-Host: 66.162.65.162
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 8bit
X-Trace: posting.google.com 1054735754 15814 127.0.0.1 (4 Jun 2003 14:09:14
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: 4 Jun 2003 14:09:14 GMT
Xref: archiver1.google.com comp.lang.ada:38601
Date: 2003-06-04T14:09:14+00:00
List-Id: <comp.lang.ada>

"Anthony Moss" <a.m@baesystems.com> wrote in message news:<3eddb5dd$1@baen1673807.greenlnk.net>...
> Is there any good documentation on calling C++ functions from a piece of ADA
> code.
> please repond
> anthony.moss@baesystems.com
> 
> Thank you.

I posted an answer to a similar question in the thread "Rational Apex
Ada - Pragma interface with C++", which occured in Oct 2002.

<http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&selm=uqbtbu6rtkk7b%40corp.supernews.com>

I got the idea from James Coplien's book Adanced C++ Programming
Styles and Idioms.  The basic idea is to bind to a factory function
written in C++, and then manipulate the object from the Ada side, e.g.

class X
{
public:
   void f();
};

extern "C" X* make_x()
{
   return new (std::nothrow) X();
}

extern "C" void free_x(X* p)
{
   delete p;
}

extern "C" void X_f(X* x)
{
   x->f();
}

You'll need to write a binding on the Ada side, e.g.

package X_Types is

   type X (<>) is limited private;

   type X_Access is access all X;
   pragma Convention (C, X_Access);
   for X_Access'Storage_Size use 0;

   function New_X return X_Access;

   procedure Free (X : in out X_Access);

   procedure F (X : X_Access);
   --or procedure F (X : access X);

private

   type X is limited null record;

end X_Types;

Implement New_X, Free, and F by calling the C++ functions, which have
been imported to the Ada program:

package body X_Types is

   function C_New_X return X_Access;
   pragma Convention (C, C_New_X);
   pragma Import (C_New_X, "new_x");  //something like that

   function New_X return X_Access is
   begin
      return C_New_X;
   end;

   ...
end X_Types;

Make sure that access types are passed by *value* to the C++ function.