Question

I have a class and I want to use it in a Qvariant, therefore I need to Declare and Register the Meta type. This is what I’ve done:

class blabla: public QThread
{
   Q_OBJECT
 .
 .
 .
 };
 Q_DECLARE_METATYPE(blabla)

But this code is giving me Error:

In copy constructor ‘QThread::QThread(const QThread&)’:
instantiated from ‘void* qMetaTypeConstructHelper(const T*) [with T = blabla]’
instantiated from ‘int qRegisterMetaType(const char*, T*) [with T = blabla]’
instantiated from here
‘QObject::QObject(const QObject&)’ is private
 within this context
In file included from UnitTest.cpp:16:0:
blabla.h: In copy constructor ‘blabla::blabla(const blabla&)’:
note: synthesized method ‘QThread::QThread(const QThread&)’ first required here 
In file included from /usr/include/QtCore/qvariant.h:48:0,
             from /usr/include/QtCore/qabstractitemmodel.h:45,
             from /usr/include/QtCore/QtCore:7,
             from /usr/include/QtTest/QtTest:3,
             from UnitTest.h:16,
             from UnitTest.cpp:14:
In function ‘void* qMetaTypeConstructHelper(const T*) [with T = blabla]’:
note: synthesized method ‘blabla::blabla(const blabla&)’ first required here 
make[1]: *** [build/obj/UnitTest.o] Error 1

I guess I need to register my met-type, but I am not sure where to have qRegisterMetaType<MyClass>("MyClass");. I tried having it after the meta type declaration macro, but resulted in error. Appriciate any comment or hint which directs me to the right path.

Answer 1

Objects are copied when put into a QVariant, but QObject derived classes cannot be copied, so the solution is to use a pointer to your class.

Q_DECLARE_METATYPE( blabla* )

Also qRegisterMetaType<T>() is only required for sending your object through queued signal/slot connections.