Re: [Vala] Vala-list Digest, Vol 26, Issue 8

[Ali Sabil <ali sabil gmail com>]

On Wed, Jan 6, 2010 at 10:20 AM, golnaz nilieh <g382nilieh gmail com> wrote:
> > On Wed, Jan 6, 2010 at 7:28 AM, Jan Hudec <bulb ucw cz> wrote:
> > > On Tue, January 5, 2010 13:12, Frederik wrote:
> > > > Non-value-type static class variables are only initialized after the
> > > > class was instantiated at least once. This behaviour is a little bit
> > > > counter-intuitive, and I hope it will change in the future.
> > >
> > > I have to disappoint you -- that behaviour can't change.
> > >
> > > The problem is, that the while the mechanism for static constructors
> > > exists for C++, there does not seem to be a portable way to use it from
> > > C (in gcc you can use the __attribute__((constructor)), but that's an
> > > extension).
> > >
> > > > You have several options:
> > > >
> > > > - create a throw-away instance:
> > > >
> > > > ? static int main (string[] args) {
> > > > ? ? ? new Global ();
> > > > ? ? ? stdout.printf ("all data is in: " + Global.dataDir);
> > > > ? ? ? return 0;
> > > > ? }
> > >
> > > Actually, there is no need to do that -- calling typeof(Global); is
> > > enough.
> > >
> > > > - call a static initialization method:
> > > >
> > > > ? static int main (string[] args) {
> > > > ? ? ? Global.init ();
> > > > ? ? ? stdout.printf ("all data is in: " + Global.dataDir);
> > > > ? ? ? return 0;
> > > > ? }
> > >
> > > This should not work. *static* methods do not cause a class to be
> > > initialized (*class* methods do, though).
> > >
> > > > - make 'dataDir' const, if it is not intended to change
> > >
> > > - make the variable a class one instead of static one.
> > >
> > > public class Global {
> > > ? ?class string dataDir = "whatever";
> > > }
> >
> > To me to correct way is to use:
> >    public static const string dataDir = "/usr/local/share/";
> > instead of:
> >    public static string dataDir = "/usr/local/share/";
> >
> > Also please follow the Vala coding conventions (data_dir instead of
> > dataDir)
> >
> > --
> > Ali
>
>
> Thanks to all. I defined an empty constructor for Global, and called it in
> main function. also I changed dataDir to a constant variable.

If you define dataDir as constant you don't need the constructor and
you don't need to call it.

> But a new question: Is there a way to pass the installation path to dataDir?
> I use this macro in configure.ac:
>
> AC_PREFIX_DEFAULT(/usr/local)
>
> can i use it as a variable in a vala source file?

I already posted a message about that in this mailing list, but it
seems like you are subscribing to a mail digest, it will take a while
before you get it.