Thank you!
On Wed, 4 Aug 2021 19:19:36 +0200
Kjell Ahlstedt wrote:
> Glib::ObjectBase is a virtual base class. The constructor of a
> virtual base class is called from the most derived class. When
> ModelImpl is the most derived class, its constructor calls
> Glib::ObjectBase(typeid(ModelImpl)). When Derived is the most derived
> class, Glib::ObjectBase(typeid(ModelImpl)) is not called. Instead
> ObjectBase's default constructor is called from Derived's
> constructor. That's not what you want in this case. You must call the
> right ObjectBase constructor from Derived's constructor, like
>
> class Derived: public ModelImpl
> {
> Derived()
> : Glib::ObjectBase(typeid(Derived)),
> ModelImpl() {}
> };
>
> Den 2021-08-04 kl. 12:15, skrev Sergey Smirnykh via gtkmm-list:
> > Hello!
> >
> > I've run into the issue I can't resolve on my own. I have
> > a Gio::ListModel implementation and a (C++) class derived
> > from said implementation.
> >
> > Calling G_IS_LIST_MODEL(gobj) on the implementation's gobj returns
> > 1. However, G_IS_LIST_MODEL(gobj) on the derived class's gobj
> > returns 0.
> >
> > How to make inheritance work? I've been unable to find any
> > guides/tutorials on this issue, hence the question.
> >
> > The implementation is defined as follows:
> >
> > class Item { ... }
> >
> > class ModelImpl: public Gio::ListModel, public Glib::Object {
> > public: ModelImpl(): Glib::ObjectBase(typeid(ModelImpl)),
> > Gio::ListModel() {}
> > virtual ~ModelImpl() = default;
> > protected:
> > std::vector items;
> > GType get_item_type_vfunc() override {
> > return Item::get_type();
> > }
> > guint get_n_items_vfunc() override {
> > return items.size();
> > }
> > gpointer get_item_vfunc(guint position) override {
> > if (position < items.size()) {
> > return items[position]->gobj();
> > }
> > return nullptr;
> > }
> > };
> >
> > And the derived class:
> >
> > class Derived: public ModelImpl {
> > Derived(): ModelImpl() {}
> > }
> >
> > Thanks in advance!
> >
> > Sergey Smirnykh
> > ___
> > gtkmm-list mailing list
> > [email protected]
> > https://mail.gnome.org/mailman/listinfo/gtkmm-list
___
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