Q_Object for specialization class

[Hu Junhao]

template <typename T>
class A
{
    T a;
};
template<>
class A<int> : public QObject
{
    Q_OBJECT
};

moc will not generate code for A<int>
I realize that Q_OBJECT will not generate code for template class. but A<int> is not

[jeremy_k]

This limitation is mentioned in the moc documentation.

https://doc.qt.io/qt-6/moc.html#limitations

moc does not handle all of C++. The main problem is that class templates cannot have the Q_OBJECT macro. Here is an example:

class SomeTemplate<int> : public QFrame
{
    Q_OBJECT
    ...

signals:
    void mySignal(int);
};

[Hu Junhao]

@jeremy_k Any alternative solution?
More detailed code like this

enum MagagerType
{
    Interface,
};

class Document
{
    template<MagagerType T>
    friend class Manager;
};

template <MagagerType T>
class Manager
{
};
template<>
class Manager<MagagerType::Interface> : public QObject
{
    Q_OBJECT
};

[ChrisW67]

@Hu-Junhao What are you trying to achieve with this arrangement?

[Hu Junhao]

@ChrisW67 As the former code shows, I have a Document class, and serveral Manager classes, all Manager classes is friend class of Document. What I have tried to achieve is to make as few changes as possible to the Document class。

[Christian Ehrlicher]

And why do you need a Q_OBJECT macro then? As already said it does not work with templates (and will not).

[Hu Junhao]

@Christian-Ehrlicher I need signals and slots, maybe there is another solution for me not to write friend declaration every time?

[Christian Ehrlicher]

@Hu-Junhao said in Q_Object for specialization class:

I need signals and slots

Then use the new signal/slot syntax.

[Hu Junhao]

@Christian-Ehrlicher You mean inherits QObject but without macro Q_OBJECT maco? Compile error on

Q_STATIC_ASSERT_X(QtPrivate::HasQ_OBJECT_Macro<typename SignalType::Object>::Value, "No Q_OBJECT in the class with the signal");

[Hu Junhao]

Sorry for all, after considering, this is absolutely a fake requirement. Manager Class will always add member to Document class. Avoid changes to Document class is meaningless.