Enable exposing readonly properties from C++

Let's assume that in code snippet below Flickable.visibleArea.xPosition should be readonly:

pragma main;

Image {
    id: root

    Flickable {
        id: flickable
    }

    Timer {
        interval: 200
        running: true
        onTriggered: flickable.visibleArea.xPosition = 5;
    }
}

In regular Qt / QML we get a following kind of error at runtime (which in case of Qt for MCUs should be a suitable compile error):

...ListView.qml:35: TypeError: Cannot assign to read-only property "xPosition"

Current workaround for exposing readonly proprties from C++ (for example in case of temperature measurement) is to implement a signal handler tempMeter.setPointer(temperature) which arguably is not very QMLish thing to do.

As suggestion:
It should be possible to specify properties as "readonly" from C++ maybe by having Qul::Property<int, Qul::ReadOnly> property extension or by implementing Qul::ReadOnlyProperty<T>.