Is the documentation correct for QMetaObject Class | Qt 4.8 ?

[SPlatten]

On this page:
https://doc.qt.io/archives/qt-4.8/qmetaobject.html#property

The sample code shows:

for(int i = metaObject->propertyOffset(); i < metaObject->propertyCount(); ++i)

Is this correct? Because in my simple code that I've created:

const QMetaObject* cpobjMO(metaObject());
for( int i=cpobjMO->propertyOffset(); i<cpobjMO->propertyCount(); ++i )

I have already added a property to the class in the constructor using:

setProperty(crstrMember.toLatin1().data(), crvarData);

Where crstrMember contains "Hello" and crvarData contains "World". When I get to the loop, both propertyOffset and propertyCount return 1, so it will not iterate at all.

[KroMignon]

@SPlatten said in Is the documentation correct for QMetaObject Class | Qt 4.8 ?:

See above results with comments.

Oh, sorry but I made the same mistake as you!
This only works for property which have been declared with Q_PROPERTY, and therefore added in the QMetaObject create by the MOC!!

What you are looking for is QObject::dynamicPropertyNames() (cf https://doc.qt.io/archives/qt-4.8/qobject.html#dynamicPropertyNames)

[KroMignon]

@SPlatten said in Is the documentation correct for QMetaObject Class | Qt 4.8 ?:

Where crstrMember contains "Hello" and crvarData contains "World". When I get to the loop, both propertyOffset and propertyCount return 1, so it will not iterate at all.

Are you sure you are testing on the right object instance?
Note: propertyOffset = 1, which is normal, property 0 is the name() property of the QObject (cf. https://doc.qt.io/archives/qt-4.8/qmetaobject.html#propertyOffset).

setProperty("Hello", "world");
const QMetaObject* cpobjMO(metaObject());
for( int i=cpobjMO->propertyOffset(); i<cpobjMO->propertyCount(); ++i )
    qDebug() << "Found" << i << "as" << QString::fromLatin1(cpobjMO->property(i).name());

[SPlatten]

@KroMignon , yes, my test code is very simple:

clsJSON objDemo;
objDemo.insert("HELLO", "WORLD");
QString strJSON(objDemo.toString());
qDebug() << strJSON;

The class itself:

clsJSON::clsJSON(QObject* pParent) : QObject(pParent) {
}
void clsJSON::insert(const QString& crstrMember, const QVariant& crvarData) {
    if ( crstrMember.isEmpty() == true || crvarData.isValid() != true ) {
        return;
    }
    setProperty(crstrMember.toLatin1().data(), crvarData);
}
QString clsJSON::toString() const {
    const QMetaObject* cpobjMO(metaObject());
    for( int i=cpobjMO->propertyOffset(); i<cpobjMO->propertyCount(); ++i ) {
        ...  
    }
    return ...;
}

toString is not compete yet, but the loop isn't getting iterated at all, I've checked and as posted propertyOffset and propertyCount both equal 1.

[SPlatten]

@KroMignon , I'm making some kind of fundamental mistake because I've just made another change to test and validate:

clsJSON::clsJSON(QObject* pParent) : QObject(pParent) {
}
void clsJSON::insert(const QString& crstrMember, const QVariant& crvarData) {
    if ( crstrMember.isEmpty() == true || crvarData.isValid() != true ) {
        return;
    }
    setProperty(crstrMember.toLatin1().data(), crvarData);
}
QString clsJSON::toString() {
    const QMetaObject* cpobjMO(metaObject());
    int intOffset = cpobjMO->propertyOffset()  // returns 1
       ,intCount = cpobjMO->propertyCount();    // returns 1
    const QString cstrTest("Another");
    const QVariant cvarData("test");
    insert(cstrTest, cvarData);
    QVariant varP1(property("HELLO"));       // Works and varP1 contains "WORLD"
    QVariant varP2(property("Another"));    // Also works varP2 contains "test"
    intOffset = cpobjMO->propertyOffset()  // still returns 1
    intCount = cpobjMO->propertyCount();    // still returns 1
    for( int i=cpobjMO->propertyOffset(); i<cpobjMO->propertyCount(); ++i ) {
        ...  
    }
    return ...;
}

See above results with comments.

[Edit] See additional to lines where I get the property data inserted and verify it is correct, yet the propertyOffset and propertyCount are both still 1.

[KroMignon]

@SPlatten said in Is the documentation correct for QMetaObject Class | Qt 4.8 ?:

See above results with comments.

Oh, sorry but I made the same mistake as you!
This only works for property which have been declared with Q_PROPERTY, and therefore added in the QMetaObject create by the MOC!!

What you are looking for is QObject::dynamicPropertyNames() (cf https://doc.qt.io/archives/qt-4.8/qobject.html#dynamicPropertyNames)

[SPlatten]

@KroMignon , Thank you, I was starting to think it had to be something very fundamental like that...I think some notes in the documentation would be useful, since the functions are called property and setProperty.