Re: SWIG backend for Ada

["Dr. Adrian Wrigley" <amtw@linuxchip.demon.co.uk.uk.uk>]

On Sat, 23 Oct 2004 11:58:40 +0200, Florian Weimer wrote:

> Is anybody developing a SWIG backend which generates Ada code?

I briefly looked at SWIG a couple of months ago, and thought it might
be interesting.  But then other things took precedence.

Now I look at it again, I think this would be a really excellent
project for Ada and Ada users!

The project could replace cbind/c2ada, which I think is ageing
somewhat, doesn't handle C++, and has some tricky dependencies (?)
The great thing is that the Ada community can benefit from the
open source work done by people on the frontend.  As I see it,
a lot of the hard work has already been done.

The Ada language interfaces seem very good when you first learn
about them, but when it comes to practical usage, it's a significant
problem keeping packages synchronised with .h C source files.
All the strong typing, error checking etc. goes out of the window
when the .h file is changed and the Ada specification no longer matches.

One day, I would like to see full integration of the Ada compiler
(eg in gnatmake, building .ads files) with C header files so you
can write something like:

with G_Lib_Top;
-- Provide Ada specification from system C header file:
-- gets subprogram declarations and type from glibtop.h
pragma Specification (C_Header, G_Lib_Top, "glibtop.h");

procedure Test is
   Var : glibtop; -- Gets record definition from C struct
begin
   GLibTop_Init; -- Call C interface
   GLibTop_Close;
end Test;

If I have some spare time, I'll have a closer look at the SWIG
distribution, and try to see how much work it would be.
-- 
Adrian Wrigley, Cambridge, UK