Логика

template <typename T>
qint64 write_helper(QFile *file, const QScriptValue &value, T *dummy = 0)
{
    Q_UNUSED(dummy)
    int count = value.property("length").toInt32();
    QByteArray ba(count * sizeof(T), '\0');
    QDataStream s(&ba, QIODevice::WriteOnly);

    for (int i = 0; i < count; ++i)
        s << value.property(i).toVariant().value<T>();

    return file->write(ba);
}