How to avoid an error when using objects of a class inherited from QObject?

Question

OOP

There is a DataSignal class that I inherit from QObject, there is also a Generator class that uses objects of this class, i.e. the generator has a method that must return an object of the DataSignal class. But when compiling, the following error is thrown:
- call to implicitly-deleted copy constructor of 'DataSignal'
- copy constructor of 'DataSignal' is implicitly deleted because base class 'QObject' has a deleted copy constructor
Signal class

#ifndef DATASIGNAL_H
#define DATASIGNAL_H

#include <QObject>
#include <QVector>

class DataSignal : public QObject
{
    Q_OBJECT
public:
    explicit DataSignal(QObject *parent = 0);
    QVector <double> getData();
    QVector <double> getTimeScale();

private:
    QVector <double> data;
    QVector <double> timeScale;

signals:
    void dataChanged(QVector <double> data);
    void timeScaleChanged(QVector <double> data);
    void cleared();

public slots:
    void setData(QVector <double> data);
    void setTimeScale(QVector <double> timeScale);
    void clear();

};

#endif // DATASIGNAL_H

In turn, our generator is inherited from the abstract class

#include <QObject>
#include "datasignal.h"
class AbstractGenerator : public QObject
{
    Q_OBJECT
public:
    explicit AbstractGenerator(QObject *parent = 0);

signals:
    void signalIsGenerated(DataSignal  *signal);

public slots:

};

The generator class itself

#include "abstractgenerator.h"
#include "filtercore.h"

class DiscreteGenerator : public AbstractGenerator
{
public:
    DiscreteGenerator();

public slots:
    DataSignal generateSimpleSignal(/*some params*/);

};

And here, in the *.cpp file, an error occurs:

DataSignal DiscreteGenerator::generateSimpleSignal(/*some params*/){
    DataSignal signal;
    /*something happens*/
    return signal;
}

Help, good people!

Answer 1

QObject has blocked copy constructors and assignment operators: Qt Object Model
No copy constructor or assignment operator
The point is that here

DataSignal DiscreteGenerator::generateSimpleSignal(/*some params*/){
    DataSignal signal;
    /*something happens*/
    return signal;
}

You first create a DataSignal object and then return a copy of it.
Try converting to a pointer:

DataSignal* DiscreteGenerator::generateSimpleSignal(/*some params*/){
    DataSignal *signal = new DataSignal;
    /*something happens*/
    return signal;
}

Answer 2

You can also explicitly define a DataSignal copy constructor that does not cause a QObject to be copied - this will make it possible to create objects on the stack. But note that such an object must be created without an owner (the QObject *parent parameter in the DataSignal constructor), since the owner considers that the child object is on the heap and tries to delete it in its destructor.