Re: [Vala] static string variable is empty!

[Ali Sabil <ali sabil gmail com>]

On Wed, Jan 6, 2010 at 10:02 AM, Andrea Bolognani <eof kiyuko org> wrote:
> On Tue, Jan 05, 2010 at 11:53:50AM +0330, golnaz nilieh wrote:
>
> > Hello everybody!
> > I'm a newbie to vala language, I faced to a strange problem recently and
> > couldn't find any help in vala documentations.
> > In my app, I have declared a class named "Global" in a file "global.vala":
> >
> > using GLib;
> > public class MyApp.Global : GLib.Object {
> >     public static string dataDir = "/usr/local/share/";
> > }
> >
> > And I have a "main.vala" file, whith this code inside:
> >
> > using GLib;
> > using Gtk;
> > public class MyApp.MainWindow : Window {
> >    static int main (string[] args) {
> >       stdout.printf ("all data is in: " + Global.dataDir);
> >       return 0;
> >    }
> > }
>
> Hi,
>
> I'm really sorry, I can't help you.
>
> But since I'm doing something similar in a software I'm writing, I'll take
> the occasion and ask a little piece of advice on the list.
>
> You are hard-coding dataDir into your application; assuming you're using
> the GNU autotools, the data directory can be configured using the --prefix
> option of configure. If that value is changed, the hard-coded dataDir will
> not point to the right directory.
>
> What I've done to work around the issue is to create a small utility class,
> where I replace the value of prefix at build time:
>
>        public class AutotoolsSupport : GLib.Object {
>                public static const string DATA_DIR = "@prefix@/share/";
>        }
>
> The above snippet goes in autotoolssupport.vala.in, so that a suitable
> autotoolssupport.vala is generated when AC_SUBS(prefix) is called in
> configure.ac.
>
> I would like to have a cleaner way to refer to @datadir@ from inside a Vala
> source file. Any suggestion?

Well actually the best way is to add a target to your Makefile.am like this:

BUILT_SOURCES=config.vala
CLEANFILES=config.vala
config.vala: config.h
        echo 'namespace Config {' >$@
        echo '  internal const string PACKAGE = "$(PACKAGE)";' >>$@
        echo '  internal const string PACKAGE_BUGREPORT = "$(PACKAGE_BUGREPORT)";' >>$@
        echo '  internal const string PACKAGE_NAME = "$(PACKAGE_NAME)";' >>$@
        echo '  internal const string PACKAGE_STRING = "$(PACKAGE_STRING)";' >>$@
        echo '  internal const string PACKAGE_TARNAME = "$(PACKAGE_TARNAME)";' >>$@
        echo '  internal const string PACKAGE_URL = "$(PACKAGE_URL)";' >>$@
        echo '  internal const string PACKAGE_VERSION = "$(PACKAGE_VERSION)";' >>$@
        echo '  internal const string PACKAGE_DATADIR = "$(datadir)";' >>$@
        echo '}' >>$@

because it is also possible to specify --datadir= or --datarootdir=
when calling the configure script.

--
Ali