Trait glib::subclass::types::IsSubclassableExt   
source · pub trait IsSubclassableExt: IsClass + ParentClassIs {
    // Required methods
    fn parent_class_init<T: ObjectSubclass>(class: &mut Class<Self>)
       where Self::Parent: IsSubclassable<T>;
    fn parent_instance_init<T: ObjectSubclass>(
        instance: &mut InitializingObject<T>
    )
       where Self::Parent: IsSubclassable<T>;
}