lqml/examples/cl-repl/cpp

Info

This demonstrates how to extend your app with Qt code callable from Lisp.

Please note that we only need QVariant arguments, which can also hold pointers which are type checked when retrieving the pointer value (that is, the pointer is a nullptr if the type doesn't match).

It also shows how to extend non QObject classes with a QObject, in order to store their pointer values in a QVariant.

If we need to return a non QObject value to Lisp (not a pointer or primitive value, but a class like TextBlock in this example, that is a QTextBlock extended with a QObject), a new instance is created on the heap, calling QTimer::singleShot(0, tmp, &QObject::deleteLater) on it, which should be sufficient in any circumstance. The additional timer is need here because of SplitView, which delays certain events.