[Interest] [External] Interface with signals and slots

[Kristoffersen, Even (NO14)]

Really late response, but why inherit QObject in MyClass rather than IMyInterface?

Since all the objects inheriting from IMyInterface needs to be QObjects you can just do this:

class IMyInterface : public QObject { Q_OBJECT etc... }
class MyClass : public IMyInterface {  Q_OBJECT and so on... }


-Even

From: Interest [mailto:interest-bounces at lists.qt-project.org] On Behalf Of Jérôme Godbout
Sent: 30. november 2018 21:38
To: interest at qt-project.org
Subject: [External] [Interest] Interface with signals and slots

Hi,
I was wondering if it's even possible to do the following somehow. I'm trying to make an Interface with signals without inheriting the QObject and I have a hard time make this compile properly:

class IMyInterface
{
public:
    explicit IMyInterface();
    virtual ~IMyInterface();

    bool val() const;
    void setVal(const bool v);

signals:
    virtual void valChanged() = 0;

protected:
    bool m_val;
};

Q_DECLARE_INTERFACE(IMyInterface, "IMyInterface")

class MyClass : public QObject, public IMyInterface
{
    Q_OBJECT
    Q_PROPERTY(bool val READ val WRITE setVal NOTIFY valChanged)
    Q_INTERFACES(IMyInterface)

public:
    ...

signals:
    virtual void valChanged() override;
};

Q_DECLARE_METATYPE(MyClass*)

The example is simplified to show my problem, the different class will inherit different QObject type so I cannot inherit 2 different QObject type. It does compile but this fail at link with the moc:

moc_MyClass.obj:moc_MyClass.cpp:vtable for MyClass: error: undefined reference to 'MyClass::dirtyChanged()'
moc_MyClass.obj:moc_MyClass.cpp:vtable for MyClass: error: undefined reference to 'non-virtual thunk to MyClass::valChanged()'
module_demo.obj:module_demo.cpp:vtable for QQmlPrivate::QQmlElement<MyClass>: error: undefined reference to 'MyClass::valChanged()'
module_demo.obj:module_demo.cpp:vtable for QQmlPrivate::QQmlElement<MyClass>: error: undefined reference to 'non-virtual thunk to MyClass::valChanged()'

Is there a way to use the signals/slots into an interface to be declared? That would greatly help me do reusable code part.


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