Properties undefined when accessed through script

mitchc

I'm encountering a problem that I've been trying to solve for a while: http://stackoverflow.com/questions/16310311/properties-undefined-only-when-accessed-through-script

A property can be accessed directly through QObject's property function, but not through JS:

@#include <QApplication>
#include <QDebug>
#include <QScriptEngine>
#include <QStringList>

class Item : public QObject
{
Q_OBJECT
public:
Q_PROPERTY(int typeId READ typeId)
Q_PROPERTY(int usesLeft READ usesLeft)

Item() :
    mTypeId(0),
    mUsesLeft(-1)
{
}

Item(int typeId) :
    mTypeId(typeId)
{
    if (typeId != 0) {
        mUsesLeft = 5;
    }
}

Item(const Item &item) :
    QObject(0)
{
    *this = item;
}

~Item()
{
}

Item& operator=(const Item& rhs)
{
    mTypeId = rhs.mTypeId;
    mUsesLeft = rhs.mUsesLeft;
    return *this;
}

int typeId() const { return mTypeId; }

int usesLeft() const { return mUsesLeft; }
void setUsesLeft(int usesLeft) { mUsesLeft = usesLeft; }

friend QDataStream &operator<<(QDataStream &out, const Item &item);
friend QDataStream &operator>>(QDataStream &in, Item &item);
friend QDebug operator<<(QDebug debug, const Item &item);

private:
int mTypeId;
int mUsesLeft;
};

QDataStream &operator<<(QDataStream &out, const Item &item)
{
out << item.typeId()
<< item.usesLeft();
return out;
}

QDataStream &operator>>(QDataStream &in, Item &item)
{
in >> item.mTypeId
>> item.mUsesLeft;
return in;
}

QDebug operator<<(QDebug debug, const Item &item)
{
debug.nospace() << "(Item typeId=" << item.typeId()
<< ", usesLeft=" << item.usesLeft();
return debug.space();
}

Q_DECLARE_METATYPE(Item)

class ItemStack : public QObject
{
Q_OBJECT
public:
Q_PROPERTY(Item *item READ item)
Q_PROPERTY(int size READ size)

ItemStack() :
    mSize(0)
{
}

ItemStack(const ItemStack &rhs) :
    QObject()
{
    *this = rhs;
}

ItemStack(const Item &item, int size) :
    mItem(item),
    mSize(size)
{
}

~ItemStack()
{
}

ItemStack& operator=(const ItemStack& rhs)
{
    if(this == &rhs) return *this;

    mItem = rhs.mItem;
    mSize = rhs.mSize;

    return *this;
}

Item* item()
{
    return &mItem;
}

const Item *item() const
{
    return &mItem;
}

int size() const
{
    return mSize;
}

friend QDataStream &operator&lt;&lt;(QDataStream &out, const ItemStack &itemStack);
friend QDataStream &operator&gt;&gt;(QDataStream &in, ItemStack &itemStack);
friend QDebug operator&lt;&lt;(QDebug debug, const ItemStack &itemStack);

private:
Item mItem;
int mSize;
};

QDataStream &operator<<(QDataStream &out, const ItemStack &itemStack)
{
out << *itemStack.item()
<< itemStack.size();
return out;
}

QDataStream &operator>>(QDataStream &in, ItemStack &itemStack)
{
in >> itemStack.mItem
>> itemStack.mSize;
return in;
}

QDebug operator<<(QDebug debug, const ItemStack &itemStack)
{
debug.nospace() << "(ItemStack item=" << *itemStack.item()
<< ", size=" << itemStack.size()
<< ")";
return debug.space();
}

Q_DECLARE_METATYPE(ItemStack)

class GunEntity : public QObject
{
Q_OBJECT
public:
Q_PROPERTY(ItemStack roundsLoaded READ roundsLoaded)

GunEntity() : mRoundsLoaded(Item(1), 7) {}

ItemStack roundsLoaded() { return mRoundsLoaded; }

private:
ItemStack mRoundsLoaded;
};

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

// Accessing directly through properties.
GunEntity ge;
qDebug() << "Can convert ge.roundsLoaded to ItemStack?" << ge.property("roundsLoaded").canConvert<ItemStack>();
ItemStack is = ge.property("roundsLoaded").value<ItemStack>();
qDebug() << is;
qDebug() << "Can convert is.item to Item?" << is.property("item").canConvert<Item*>();
qDebug() << *is.property("item").value<Item*>();
qDebug() << "Can convert is.size to int?" << is.property("size").canConvert<int>();
qDebug() << is.property("size").toInt();

// Accessing through QScriptEngine.
QScriptEngine se;
se.evaluate("function blah(gun) { print(gun.roundsLoaded); print(gun.roundsLoaded.item); print(gun.roundsLoaded.size); }");
if (se.hasUncaughtException()) {
    qDebug() << se.uncaughtException().toString() << ":"
             << se.uncaughtExceptionLineNumber() << se.uncaughtExceptionBacktrace();
}
QScriptValueList args;
args << se.newQObject(&ge);
QScriptValue ret = se.globalObject().property("blah").call(se.globalObject(), args);

if (se.hasUncaughtException()) {
    qDebug() << se.uncaughtException().toString() << ":"
             << se.uncaughtExceptionLineNumber() << se.uncaughtExceptionBacktrace();
}

return 0;

}

#include "main.moc"@

Any suggestions are welcomed. :)