Support to compile Vala language project

[waruqi]

• https://wiki.gnome.org/Projects/Vala
• https://wiki.gnome.org/Projects/Vala/SDLSample?highlight=%28%5CbVala%2FExamples%5Cb%29
• https://github.com/gerito1/vala-gtk-examples

[waruqi]

#1538

[waruqi]

add_rules("mode.release", "mode.debug")

add_requires("lua", "glib")

target("test")
    set_kind("binary")
    add_rules("vala")
    add_files("src/*.vala")
    add_packages("lua", "glib")
    add_values("vala.packages", "lua")

main.vala

using Lua;

static int my_func (LuaVM vm) {
    stdout.printf ("Vala Code From Lua Code! (%f)\n", vm.to_number (1));
    return 1;
}

static int main (string[] args) {

    string code = """
            print "Lua Code From Vala Code!"
            my_func(33)
        """;

    var vm = new LuaVM ();
    vm.open_libs ();
    vm.register ("my_func", my_func);
    vm.do_string (code);

    return 0;
}

[waruqi]

More examples: https://github.com/xmake-io/xmake/tree/dev/tests/projects/vala

[waruqi]

support libraries #1618