Re: Setting custom Glib::Property values in Gtk::Builder .ui XML

[Kjell Ahlstedt <kjellahlstedt gmail com>]

On 6/10/19 6:50 PM, Kjell Ahlstedt wrote:
> On 6/10/19 10:39 AM, Daniel Boles via gtkmm-list wrote:
> > A related question here is: How can we ensure the derived type is 
> > registered with GObject before GtkBuilder would need it? Will a 
> > simple g_type_ensure( g_type_from_name("gtkmm__Custom_Whatever") ) 
> > work? I imagine not, as the GObject class won't exist until C++ 
> > constructs the first instance, right? Then it would seem we must 
> > instead create a dummy C++ instance (and ensure it isn't optimised 
> > out) before trying anything that would require GObject to know about 
> > it...
> I think you're right. The only way to have a custom widget's type 
> registered in the GType system is to create an instance. All the 
> ordinary gtkmm types are registered with calls to the static 
> get_type() methods. That's done in wrap_init(). But there is no 
> corresponding method to call for custom types.
Now that I've thought a second time, I wonder if it's really necessary 
to use Glib::ExtraClassInit, and install the custom properties in the 
class init func. Glib::Property<> installs properties with a call to 
g_object_class_install_property(), but it's not done in the class init 
func. Does it matter if it's done later, as long as it's done before 
GtkBuilder reads the .ui file? I mean, if you anyway have to create an 
instance of the custom widget in order to get the class registered in 
the GType system.