[Qt-interest] Retrieving QMetaObject from a Qt Meta Type ID

[Stephen Kelly]

Sean Harmer wrote:

> Hi,
> 
> On Monday 24 January 2011 17:04:56 Gustavo de Sá Carvalho Honorato wrote:
>> I have a method that returns QVariant with any type. I have some
>> pointer types pointing to an object derived from QObject, which are
>> registered using Q_DECLARE_METATYPE. When this method returns these
>> pointers to QObject derived objects, I need to list all properties,
>> slots and others thinks related to its meta object. The problem is
>> that I didn't find any way disconver if this QVariant is holding a
>> pointer to a QObject derived type to get the QMetaObject and finally
>> list the properties. The purpouse of this is to expose QObject to a
>> scripting system, like QScriptEngine does.
>> 
>> Any ideas?
> 
> There are probably more elegant ways but this should work:
> 
> int typeId = myVariant.userType();
> QObject* object = QMetaType::construct( typeId );
> QMetaObject metaObject = object->metaObject();
> ...
> QMetaType::destroy( typeId, object );

QObject *object = myVariant.value<QObject*>();
if (object)
    QMetaObject *metaObject = object->metaObject();

> 
> Or if you want to use your existing object stored in the variant use
> qobject_cast to get it back to a QObject pointer and then get the
> metaobject from that.
> 
> HTH,
> 
> Sean