Multiple heritance

[Roy44]

Hi,

This question has probably been asked 10000000th times.
I would like to do something like this:

class EditorBase : public QObject
{
  Q_OBJECT
  //some code
  signals:
     void sg_mySignal();

  public slots:
     void onSlot();
};

class MyEditor : public QLineEdit, public EditorBase
{
   Q_OBJECT
   // code
};

I saw examples with Q_DECLARE_INTERFACE but interfaces do not contain signals or slot.
So is it possible ? ans How.

Thanks,
sorry for my horrible english

[kshegunov]

@Roy44 said in Multiple heritance:

So is it possible ?

No, not with QObjects.

[ambershark]

@Roy44 Multiple inheritance is rarely a good idea. In 20 years of C++ I think I have used it once.

There is usually a better way than using multiple inheritance. In this case you could pass in a QLineEdit or just create one as a member of MyEditor.

[mtrch]

In this case you probably don't need EditorBase class, because signals & slots are connected dynamically, using Qt meta-object system, so you can create connections passing base QObject* pointer as argument:

QObject *editor = new MyEditor(parent);
//QLineEdit signals & slots:
connect(editor, SIGNAL(textChanged(QString)), SLOT(someSlot(QString)));
//MyEditor signals & slots
connect(editor, SIGNAL(sg_mySignal()), SLOT(otherSlot()));
connect(button, SIGNAL(clicked()), editor, SLOT(onSlot()));

[kshegunov]

@ambershark said in Multiple heritance:

Multiple inheritance is rarely a good idea. In 20 years of C++ I think I have used it once.

Funnily, I have a similar story. ;)

@Roy44
As @ambershark suggested the usual thing to do in this case is to aggregate the line edit (i.e. have it as a member) and if necessary to forward its signals.