I'm trying to develop a class that will be used in a reflection driven application and I ran into an interesting issue that I'm hoping there is a solution to. Let's say I have a class Dummy that has a few properties, one of which is a pointer to another Dummy object:
Qt Code: 
  1. class Dummy : public QObject
  2. {
  3.     Q_OBJECT
  4.     Q_PROPERTY(int id READ id WRITE setId)
  5.     Q_PROPERTY(QObject * child READ child)
  6.  
  7.     int myId;
  8.     DummyObject *myChild;
  9.  
  10. public:
  11.  
  12.     Dummy(int id)
  13.         : myId(id), myChild(0)
  14.     {
  15.         if (myId == 0)
  16.         {
  17.             myChild = new Dummy(myId + 1);
  18.         }
  19.     }
  20.  
  21.     ~Dummy()
  22.     {
  23.         delete myChild;
  24.     }
  25.  
  26.     int id() const
  27.     {
  28.         return myId;
  29.     }
  30.  
  31.     void setId(int id)
  32.     {
  33.         myId = id;
  34.     }
  35.  
  36.     QObject * child()
  37.     {
  38.         return myChild;
  39.     }
  40.  
  41. };
To copy to clipboard, switch view to plain text mode 

And then lets say I create a new Dummy object with id = 0 (so it has one child with id = 1), if I pass the parent Dummy object to a function that takes a constant reference to a QObject (or a constant pointer for that matter), how can I guarantee const-correctness on the child function? I tried the obvious: Q_PROPERTY(const QObject * child READ child) and then making const QObject * child() const (which is really how I want this function to look like), but then the moc complains about: "Unable to handle unregistered datatype 'const QObject*'". I just can't figure out how to make it so that if I pass a constant reference or pointer to a Dummy object that the "child" function (through the qt property system) will expose a constant reference or pointer (to ensure const-correctness).