Re: [Vala] Type.from_name() / unregistered types

[Dennis Möhlmann <in dev nyda info>]

Thanks!

I've looked some more into it but went with a hardcoded name -> type map
for now. It's a nice-to-have to improve maintainability and I'll get
back to it once the project is bit further along the road.

Thanks again,
  Dennis

Am 23.08.2012 21:03, schrieb Evan Nemerson:
> On Thu, 2012-08-23 at 12:20 +0200, Dennis Möhlmann wrote:
> > Hello,
> >
> > I'm looking for a way to to create instances of a class (all subclasses
> > of a common parent) by its class-name (string, not identifier).
> > Type.from_name() + Object.new() seem to work well, but only if the type
> > has been used before (i.e. instanced or typeof()'ed). Otherwise the
> > result is Type.INVALID.
> > I have no previous knowledge of the GObject system, but apparently a
> > type needs to be registered and vala does that automatically once the
> > type used in some way. Is it possible to do this manually with only the
> > string name of the type available?
>
> Maybe.  You need to call the *_get_type function which Vala generates
> for each type.  If you have a string representing the type name you
> could parse it to guess the right function name (e.g., FooBar ->
> foo_bar_get_type), then use GLib.Module.open + GLib.Module.symbol to get
> an address.  Keep in mind, though, that you need the type names at the C
> level, not the Vala level, which may be completely different.  Also, if
> you're integrating with code written in C the names of the get_type
> functions may not be the same as they would have been had they been
> generated by valac.
>
> You could also try gobject-introspection.
>
> It's hard to say for sure without more knowledge of what you're trying
> to do, but my guess is that something like
> https://live.gnome.org/Vala/TypeModules (or possibly libpeas) would be a
> better way to go.
>
>
> -Evan