QObject::MetaObject()

[pkj]

Hi,
Suppose class A subclasses QObject and class B subclasses class A. Now if i store class B pointer in QObject * obj and call obj->MetaObject(), the metaObject I receive contains metatype information of class A and nothing of class B. Can I drill down information of class B with the class hierarchy I have, or class B must inherit from QObject directly if I am to see into metaobject properties of class B. I see that QObject::MetaObject() is virtual. Will reimplementing it in class B help?

[Lykurg]

Then you are doing something wrong.

#include <QtGui>
#include <QDebug>
 
class A: public QObject {
    Q_OBJECT
    Q_PROPERTY(int propA READ propA WRITE setPropA USER true)
 
public:
    int propA() const {return m_propA;}
    void setPropA(int propA) {m_propA = propA;}
 
private:
    int m_propA;
};
 
class B: public A {
    Q_OBJECT
    Q_PROPERTY(int propB READ propB WRITE setPropB USER true)
 
public:
    int propB() const {return m_propB;}
    void setPropB(int propB) {m_propB = propB;}
 
private:
    int m_propB;
};
 
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
 
    QObject *b = new B;
 
    const QMetaObject *o = b->metaObject();
 
    qWarning() << o->className();
    QStringList properties;
     for(int i = 0; i < o->propertyCount(); ++i)
         properties << QString::fromLatin1(o->property(i).name());
    qWarning() << properties;
 
 
    delete b;
    return 0;
}
#include "main.moc"

#include <QtGui>
#include <QDebug>

class A: public QObject {
    Q_OBJECT
    Q_PROPERTY(int propA READ propA WRITE setPropA USER true)

public:
    int propA() const {return m_propA;}
    void setPropA(int propA) {m_propA = propA;}

private:
    int m_propA;
};

class B: public A {
    Q_OBJECT
    Q_PROPERTY(int propB READ propB WRITE setPropB USER true)

public:
    int propB() const {return m_propB;}
    void setPropB(int propB) {m_propB = propB;}

private:
    int m_propB;
};


int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QObject *b = new B;

    const QMetaObject *o = b->metaObject();

    qWarning() << o->className();
    QStringList properties;
     for(int i = 0; i < o->propertyCount(); ++i)
         properties << QString::fromLatin1(o->property(i).name());
    qWarning() << properties;


    delete b;
    return 0;
}
#include "main.moc"

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works perfect.

[joyer83]

Sounds like you have forgotten to add Q_OBJECT-macro to your class B.

[pkj]

I missed Q_OBJECT macro.. eeks... joyer83 u were right... And after I did add I ran into all sorts of trouble.. untill i came to know i have to qmake again...