[Interest] Interface with signals and slots

[Jérôme Godbout]

For me, under Android target, it does fail for the linking. I was trying to add and interface for injecting property into object expose to Qml. I often want to add a subset of property to a model and I would have want to have to rewrite the same Q_PROPERTY() and changed signal over and over again.

But I guess I will stick with the ugly macro mess for now.

Would be nice to have a way to extend a QObject with defined class of property with get/set and changed signals that is not a QObject to avoid diamond inheritance since it could already inherit another QObject class.

For example I would have love to have interface for the dirty property so I could inject the property on many qobjects types I have without rewriting it every time. I can make the get/set/ protected value, but I still have to create the signals/slots/Q_PROPERTY every time. I use some macro but I find that ugly and error prone to forget one.


From: Konstantin Shegunov <kshegunov at gmail.com>
Sent: November 30, 2018 4:29 PM
To: Jérôme Godbout <godboutj at amotus.ca>
Cc: Interests Qt <interest at qt-project.org>
Subject: Re: [Interest] Interface with signals and slots

Hi,
This compiles for me:

class SignalInterface

{

public:

    virtual void mysignal() = 0;

};



class SignalImplementer : public QObject, public SignalInterface

{

    Q_OBJECT



signals:

    void mysignal() override;

};

However putting signals into an interface I think is rather dubious, because you won't be able to connect through the interface. I.e. this:

SignalImplementer obj;

QObject::connect(this, &Session::opened, &obj, &SignalInterface::mysignal);


Is going to fail the static assertions in QObject::connect.
You could derive from QObject though and have them in an abstract class.
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