copy constructor of derived QT class

Question

I have a class which is publicly inherited from QWidget:

class MyWidget : public QWidget
{
    Q_OBJECT
public:
    MyWidget(const MyWidget&         


        

Answer 1

All Qt classes are noncopyable by deriving from QObject.

It is common practice in C++ to forbid certain value-semantic operations like copying on polymorphic objects. Qt gives some examples of the problems that would arise if copy was allowed for QObject in its documentation:

A Qt Object...

• might have a unique QObject::objectName(). If we copy a Qt Object, what name should we give the copy?
• has a location in an object hierarchy. If we copy a Qt Object, where should the copy be located?
• can be connected to other Qt Objects to emit signals to them or to receive signals emitted by them. If we copy a Qt Object, how should we transfer these connections to the copy?
• can have new properties added to it at runtime that are not declared in the C++ class. If we copy a Qt Object, should the copy include the properties that were added to the original?