main.cpp

 
#include <iostream>
#include <QCoreApplication>
#include <QTimer>
 
#include "param.h"
 
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
 
//    qRegisterMetaType<Param>("CopyConstructorParam");
    qRegisterMetaType<Param>("Param");
 
    Test t;
 
    QTimer::singleShot(200, &t, SLOT(run()));
    return a.exec();
}

param.h

// Test for http://stackoverflow.com/questions/8455887/stack-object-qt-signal-and-parameter-as-reference/

#ifndef PARAM_H
#define PARAM_H

#include <iostream>
#include <QCoreApplication>
#include <QDebug>

class Param {
public:
    Param () {}
    Param (Param const &) {
        std::cout << "Calling Copy Constructor\n";
    }
};

class Test : public QObject {
    Q_OBJECT

public:
    Test () {
        for (int index = 0; index < 3; index++) {
            connect(
                this, SIGNAL(transmit(Param)),
                this, SLOT(receive(Param)),
                Qt::QueuedConnection
            );
        }
    }

public slots:
    void run() {
        Param p;
        std::cout << "transmitting with " << &p << " as parameter\n";
        emit transmit(p);
    }

signals:
    void transmit(const Param& p);
public slots:
    void receive(const Param& p) {
        std::cout << "receive called with " << &p << " as parameter\n";
    }
};

#endif // PARAM_H