I remember writing a GTK extension widget many years ago, and yes, it was very much like this. The macros end up making your very own hand-coded vtable-equivale

I remember writing a GTK extension widget many years ago, and yes, it was very much like this. The macros end up making your very own hand-coded vtable-equivalent, so that function calls get dispatched to the appropriate point in the inheritance chain. It was pretty eye-opening!