Is it necessary to delete an object if that runs on a QThread if finished signal of QThread is connected to deleteLater?

Question

So I have the following code in the constructor.

m_someObject = new SomeObject();
m_someObject->moveToThread(&m_thread);
m_thread.start();

connect(&m_thread, &QThread::finished, m_someObject, &QObject::deleteLater);

Any I have the following code in the destructor.

 m_thread.terminate();
 while (m_thread.isRunning())
 {
 }

Do I still have to delete m_someObject despite having finished of m_thread connected to deleteLater slot of m_someObject?

Answer 1

No it is not necessary. The connection should do exactly what you want as long as the thread does emit finished eventually. See the following Code:

#include <QObject>
#include <QThread>
#include <iostream>

class Test : public QObject {
    Q_OBJECT
public:
    Test(){
        std::cout <<"c'tor" << std::endl;
    }
    ~Test(){
        std::cout << "d'tor" << std::endl;
    }
};

void startThread(){
    QThread* thr = new QThread();
    Test* test = new Test();
    connect(thr, &QThread::finished, test, &QObject::deleteLater);
    test->moveToThread( thr );
    thr->start();
    thr->quit();
    thr->wait();
    delete thr;
}

The output is as expected:

c'tor
d'tor

Note that the snippet wont compile right away since its missing a main.