Re: GNAT and GNU build system

[Ludovic Brenta <ludovic.brenta@insalien.org>]

Tapio Kelloniemi writes:
> I would really prefer typing:
> ./configure --prefix=/usr --enable-goldobj

I understand your concern completely.  My concern, though, is the
sheer complecity of the ./configure script itself, and that of the
Makefile it generates.  Most of that complexity is unnecessary with
Ada programs, and in fact really gets in the way.  With Ada, you would
normally want to take full advantage of GNAT project files.  The only
places where ./configure may be of help are for the installation
target (--prefix), and finding any Ada libraries you depend on.

<plug mode=shameless>

This problem is solved nicely in Debian GNU/Linux.  Each library has a
GNAT project file in a well-known location
(/usr/share/ada/adalib/library.gpr).  Your program just "withs" them
as required.

</plug>

Furthermore, on non-Debian systems, the GNU Ada Environment
Specification[1] says where library files should be installed.  Here
again, you would not need a ./configure at all; just use -aI and -aO
as necessary.

<plug mode="really_shameless">

Since Debian follows the GNAE, your GNAT project file can be portable
without the need for ./configure.

</plug>

[1] http://cert.uni-stuttgart.de/projects/ada/gnae.php

So, you could consider writing a ./configure script by hand, which
would generate a minimal Makefile containing only the value of
--prefix.  Something along the lines of:

PREFIX=/usr

all: my_program

my_program:
        gnatmake -Pmy_program.gpr

install: my_program
        cp my_program $(PREFIX)/bin

If you need package-specific options (e.g. --enable-gold-objects),
then you can extend the ./configure and generate something like:

PREFIX=/usr
GOLD_OBJECTS=false

all: my_program

my_program:
        gnatmake -Pmy_program.gpr -XGOLD_OBJECTS=$(GOLD_OBJECTS)

install: my_program
        cp my_program $(PREFIX)/bin

-- 
Ludovic Brenta.