Qt5 new signal/slot connection syntax

mistralegna

Hello,

If I have a class B derived from class A, where class A declares signals and implements virtual slots, is there a way to connect the overriden slots of an instance of class B stored as a pointer on A with the new syntax QObject::connect ?

Thank you by advance!

jsulm

@mistralegna I don't know for sure, but you can just try and see how it behaves?

VRonin

It works out of the box...
The example below will print "b"

a.h

#ifndef A_H
#define A_H
#include <QObject>
#include <QDebug>
class A : public QObject
{
    Q_OBJECT
public:
    explicit A(QObject *parent = nullptr) : QObject(parent){}
    virtual ~A() = default;
public slots:
    virtual void test(){
        qDebug("a");
    }


};
#endif // A_H

b.h

#ifndef B_H
#define B_H

#include "a.h"

class B : public A
{
    Q_OBJECT
public:
    explicit B(QObject *parent = nullptr) : A(parent){};
    virtual ~B() = default;
public slots:
    virtual void test() override{
        qDebug("b");
    }
};

#endif // B_H

main.cpp

#include <QCoreApplication>
#include "b.h"
#include <QTimer>


int main(int argc, char *argv[]) {
    QCoreApplication appl(argc,argv);
    A* testingB=new B();
    QTimer testTimer;
    testTimer.setSingleShot(true);
    QObject::connect(&testTimer,&QTimer::timeout,testingB,&A::test);
    testTimer.start(100);
    appl.exec();
    delete testingB;
    return 0;
}

mistralegna

Thank you very much for your answer.

Is it possible to use this syntax without having to include the headers where the signals/slots are defined ?

Thank you by advance!

VRonin

@mistralegna In my example you can #include "a.h" instead of #include "b.h" in main.cpp as long as testingB is created somewhere else