Two questions about gpr files

Two questions about gpr files

[mockturtle]

Dear all, 
in my spare time I am writing a program that I would like

  (a)  to run on different systems (e.g., Windows, Linux, ...) 
despite the fact that it needs to access to some system-specific 
features that are outside the scope of the standard.

  (b)  to use a GTK-based interface, but falling down to a text-based
one (e.g., ncurses) if GTK is not available at compilation time

I could solve those two problems if it was possible to find within the *.gpr file the type of system and if a given project file is present.  For example, with something like

  case OS is
    when "Linux" =>
      OS_Dependent_Source_Dir := "src/linux";

    when "Windows" =>
      OS_Dependent_Source_Dir := "src/win";
  end case;

Well, you got the idea... (to be honest, I cannot imagine how to do a "conditional with" of gtkada.gpr with the current syntax).

I looked around the gprbuild documentation, but I was not able to find anything.  I know I could use external variables, such as reading environment variables or use the -X switch, but I would like a solution that works on any OS (OK, most of the commonly used OSes :-) and it requires no special intervention from the user that compiles the code.

Any ideas?

Thank you in advance for any help.

Riccardo

Re: Two questions about gpr files

[Simon Wright]

mockturtle <framefritti@gmail.com> writes:

> I could solve those two problems if it was possible to find within the
> *.gpr file the type of system and if a given project file is present.
> For example, with something like
>
>   case OS is
>     when "Linux" =>
>       OS_Dependent_Source_Dir := "src/linux";
>
>     when "Windows" =>
>       OS_Dependent_Source_Dir := "src/win";
>   end case;

You might find "aggregate projects" useful, especially the last part of
section 1.7.3.

http://docs.adacore.com/gprbuild-docs/html/gprbuild_ug.html#Define-a-build-environment

Re: Two questions about gpr files

[Stephen Leake]

mockturtle <framefritti@gmail.com> writes:

>   (a)  to run on different systems (e.g., Windows, Linux, ...) 
> despite the fact that it needs to access to some system-specific 
> features that are outside the scope of the standard.
>
>   (b)  to use a GTK-based interface, but falling down to a text-based
> one (e.g., ncurses) if GTK is not available at compilation time
>
> <snip>
>
> I looked around the gprbuild documentation, but I was not able to find anything.  I know I could use external variables, such as reading environment variables or use the -X switch, but I would like a solution that works on any OS (OK, most of the commonly used OSes :-) and it requires no special intervention from the user that compiles the code.
>
> Any ideas?

use a Makefile, and or a configure script.

See gnatcoll for detailed ideas.

-- 
-- Stephe

Re: Two questions about gpr files

[Dmitry A. Kazakov]

On Tue, 08 Apr 2014 03:07:30 -0500, Stephen Leake wrote:

> use a Makefile, and or a configure script.

Never ever use Makefile. If you want your project stay useful. Make a
mental experiment. Let you download any project that uses Makefile,
including Ada projects. What are chances that you will be able to compile
it? Without ./configure it is less than 10%. With ./configure it is less
than 1%. For anything complex (e.g. GtkAda) it is plain 0%.

The best way to do conditional "with" (the method suggested by Simon does
not work, I tried it before), is to include the project always but make it
empty for the targets it does not support (e.g. no source files).
 
-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de