[Qt-interest] How to create object instance knowing only its class name in a QString?

[Mandeep Sandhu]

On Mon, Jan 30, 2012 at 6:27 PM,  <frares at gmail.com> wrote:
> Hi, all.
>
> How do I instantiate an object knowing its class name in a QString and that
> all similar classes are derived from a "facade" super class?
>

You can use the factory pattern here. The QMetaObject class is your
friend in such cases.
Eg: You can keep  a map of class names to their corresponding static
meta-objects and then invoke QMetaObject::newInstance() to create an
object of that class.

Here's some sample code:

class ObjectFactory
{
public:
    template<class T>
    void registerClass(const QString &className)
    {
        m_factoryObjects.insert(className, &(T::staticMetaObject));
    }

    template<class T>
    T* createObject(const QString &className, QObject *parent = 0)
    {
        const QMetaObject *meta = m_factoryObjects.value(className);

        return (meta ?
                qobject_cast<T *>(meta->newInstance(Q_ARG(QObject *, parent)))
                    : 0);
    }

private:
    QHash<QString, const QMetaObject *> m_factoryObjects;
};

HTH,
-mandeep