Reflection on Qt

tchoninho

Hi everybody, I would use Reflection on Qt, but I do not know how I can do that. In Java, any object can be instantiated and be called even if unknown. In Qt, I can only do this when I know that this object. Has anyone used Reflection in Qt?

In my Object:

@
class Obj : public QObject
{
Q_OBJECT

public:
Q_INVOKABLE Obj(QObject *parent = 0);
Q_INVOKABLE virtual ~Obj();

Q_INVOKABLE virtual QVariant execute (QList<QVariant> &);
Q_INVOKABLE uint getKey();

};
@

andre

I don't know much about Java or its reflection features. Does QMetaObject provide what you need?

giesbert

Reflection itself does not exist in C++ (see wikipedia: http://en.wikipedia.org/wiki/Reflection_(computer_programming) ).
To use the meta data system, you can achive something like that, but not for constructors (which you seem to think in the above code snippet).

andre

Actually, Q_INVOKABLE is possible on constructors, and if you have such a constructor, you can use QMetaObject::newInstance to create an object of the requested type. But I am not sure that is what tchoninho is after?

HuXiKa

Well, you could do some nasty thing like this:

@typedef QVariant (Obj::*pt2Member)(QList<QVariant> &);
QMap<QString, pt2Member> functions;
..
functions.insert("execute",&Obj::execute());
..
QVariant result = functions["execute"](QList<QVariant> &);
@

Use this if there is no other option :)
(You will still need a this reference I think, haven't tried this out!)