openSUSE:Packaging Vala

Vala

How to detect Vala version in specfile

We assume you're not building Vala itself. If so, the version of Vala is defined by youself and can be called simply using %{version} tag, the problem does not even exist. Here we're facing such an embarrassing situation:

The package is built with Vala, and is built well under all versions of Vala(So you don't have to gild the lily by BuildRequires: vala >= 0.14 tag). But you still have to detect and use the version number of Vala.

Here Build Service got a bottleneck. For now, Vala can not simply be included with BuildRequires: vala and exports its version simple and naive with automatic tag like %{py_ver} or %{perl_version} as Perl or Python does. Some package do need to know Vala's number to get its work done(eg.., Babl or Gegl will install .vapi file to /usr/share/vala by default, but that directory is meaningless in a standard openSUSE system. However, openSUSE use directory suffixed with a Vala version number like /usr/share/vala-0.14. Now it is you packager's responsibility to move them from package default directory to openSUSE's callable).

Of course you could, by using %if 0%{?suse_version} >= 1140 tag, move them to the directory suffixed with standard Vala version number, which is installed by default on that 1140 version of openSUSE. But it will make your specfile huge and unmaintainable(you have to add such section for almost every version of openSUSE).

Now we use the self defined function %define in specfile，as follows：

 #import Vala dependency 
 BuildRequires: vala
 #define a function to export Vala's version number
 %define vala_version %(rpm -q --queryformat='%%{VERSION}' vala | sed 's/\.[0-9]*$//g')

We use rpm -q --queryformat='%%{VERSION}' vala to fetch Vala's full version number 0.14.0, which is installed in a standard RPM way before the build process actually starts, that's why such code works. And then use sed shell command with the power of Regex to cut the suffix .0 and export the result to a variable vala_version, which can be called easily by %{vala_version}. eg:

 #create a new directory. -pv means export directories it made into logfile for futher debug 
 #and create it automatically if the parent directory does not exist.
 mkdir -pv %{buildroot}%{_datadir}/vala-%{vala_version}/
 #move the files
 mv %{buildroot}%{_datadir}/vala/* %{buildroot}%{_datadir}/vala-%{vala_version}/
 #delete the original folder
 rm -Rf %{buildroot}%{_datadir}/vala/

Even in %files section, you could use:

 %dir %{_datadir}/vala-%{vala_version}/
 %{_datadir}/vala-%{vala_version}/*

to simplify your specfile.

Because every file under %{buildroot} will be packaged by hierarchy into the final output RPM, now your package's user friendliness pops up +1.