Re: [Vala] Inspecting class hierarchy

[Gergely Polonkai <gergely polonkai eu>]

Hello,

I do something similar in matrix-glib-sdk[1]: I get one specific key from a
JSON object, and based on that key I create different types of objects. For
that I have a type registry, which tells me what objects must be created
for what event type.

Your GtkBuilder approach also looks nice, although GTK would be a too heavy
dependency for my project.

Best,
Gergely

[1]
https://github.com/gergelypolonkai/matrix-glib-sdk/blob/develop/src/matrix-event-base.vala
On Mar 21, 2016 10:37 PM, "Alan Manuel Gloria" <almkglor gmail com> wrote:

> 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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