Re: [Vala] Inspecting class hierarchy

[Alan Manuel Gloria <almkglor gmail com>]

Yes, that's what I thought too.

However, looking at GtkBuilder's source code, it has a function called
type_name_mangle which converts a name like "GtkButton" to
"gtk_button_get_type", then uses GModule to load that function.  Vala's C
generation seems to create a function of the same/similar naming
convention, so the equivalent of typeof(Weapon) in C is weapon_get_type().

As a sketch, I suppose something like this ought to work:

[CCode (has_target=false)]
private delegate Type TypeOf();
...
var module = Module.open(null, 0); // opens the program itself instead of a
different module
TypeOf get_type;
module.symbol("weapon_get_type", (void*) &get_type); // the real program
needs to generate the name and check the return value here
Type type = get_type();

Object obj = Object.create(type, "damage", 10);
...


On Tue, Mar 22, 2016 at 2:19 AM, Felipe Lavratti <felipelav gmail com>
wrote:

> Hello, this is the minimum workaround I found to work, there might be a
> simpler way of forcing the registration of non-literally used classes in
> the GObject system.
>
> public class Weapon : Object {
>   public uint damage { get; construct; }
> }
>
> int main () {
>
>     /* Force class registration here, comment this line to see the
> execution failing. */
>     var klass = typeof(Weapon);
>
>     Type WeaponType = Type.from_name("Weapon");
>     Object weapon = Object.new(WeaponType, damage: 10);
>
>     GLib.message("weapon.damage = %u", (weapon as Weapon).damage);
>
>     return 0;
> }
>
>
> On Mon, Mar 21, 2016 at 10:47 AM Gergely Polonkai <gergely polonkai eu>
> wrote:
>
> > Hello,
> >
> > for the first sight your format looks verybsimilar to key-value files
> > already supported by GLib:
> >
> > https://developer.gnome.org/glib/stable/glib-Key-value-file-parser.html
> > http://valadoc.org/#!api=glib-2.0/GLib.KeyFile
> >
> > Are you sure it won't work for your problem? If it would, you may want to
> > subclass it.
> >
> > Best,
> > Gergely
> > On Mar 21, 2016 2:26 PM, "Alan Manuel Gloria" <almkglor gmail com> wrote:
> >
> > > Hi Vala world,
> > >
> > > I'm trying to make some kind of description loader.  I have a base class
> > > like so:
> > >
> > > class Concept : Object {
> > >   string name { get; construct; }
> > >   string desc { get; construct; }
> > > }
> > >
> > > And one or more classes, e.g.:
> > >
> > > class Component : Concept {
> > >   uint size { get; construct; }
> > >   uint cost { get; construct; }
> > > }
> > > class Weapon : Component {
> > >   uint damage { get; construct; }
> > > }
> > >
> > > My goal is to parse some text file like so:
> > >
> > > [Blaster I]
> > > type = Weapon
> > > desc = A simple blaster.
> > > size = 20
> > > cost = 200
> > > damage = 1
> > >
> > > Then the parser class will provide a collection of Concept objects
> > > indexable by name and type.
> > >
> > > My question is, how do I best do this?  Gtk.Buildable seems to
> > approximate
> > > what I want, so I suppose I need to figure out how that works.
> > >
> > > My initial research seems to suggest that I need to use GLib.Type
> > somehow,
> > > but my understanding is that the exact type does not get created until
> > it
> > > is used.  It seems to me that I'd need code like:
> > >
> > > var p = new MyTextFileParser();
> > > p.register(typeof(Component));
> > > p.register(typeof(Weapon));
> > > // ... and so on ...
> > >
> > > Thanks in advance.
> > >
> > > Sincerely,
> > > AmkG
> > > _______________________________________________
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