Question

As the QObject documentation and many others explain, a QObject has an identity and thus hides its copy constructor and assignment operator.

However, I’m not deriving from QObject for its dynamic properties feature or the signals/slots feature. I only want reflection, or the ability to access Foo::staticMetaObject.

class Foo : public QObject {
    Q_OBJECT
    Q_ENUMS(Color)
public:
    enum Color { Blue, Red, Pink };
private:
    Color color;
};

Q_DECLARE_METATYPE(Foo::Color)

I then can’t copy Foo with:

Foo a;
Foo b;
a = b;

What’s the best way to allow copy and assignment in this case? Do I absolutely need to write a copy constructor and assignment operator? What would they look like? Will reflection still work?

Answer 1

If you are only interested in having reflection for

• the class name,
• enums and flags (Q_ENUMS, Q_FLAGS),
• class info (Q_CLASSINFO),

you can use Q_GADGET instead of Q_OBJECT:

class Foo {
    Q_GADGET
    Q_ENUMS(Color)
public:
    enum Color { Blue, Red, Pink };
private:
    Color color;
};

which will declare and define Foo::staticMetaObject.