Is QThread doc correct?

[qwe3]

Hi,

In QThread docs, in detailed description section I see an example:

class Worker : public QObject
{
    Q_OBJECT

public slots:
    void doWork(const QString &parameter) {
        QString result;
        /* ... here is the expensive or blocking operation ... */
        emit resultReady(result);
    }

signals:
    void resultReady(const QString &result);
};

class Controller : public QObject
{
    Q_OBJECT
    QThread workerThread;
public:
    Controller() {
        Worker *worker = new Worker;
        worker->moveToThread(&workerThread);
        connect(&workerThread, &QThread::finished, worker, &QObject::deleteLater);
        connect(this, &Controller::operate, worker, &Worker::doWork);
        connect(worker, &Worker::resultReady, this, &Controller::handleResults);
        workerThread.start();
    }
    ~Controller() {
        workerThread.quit();
        workerThread.wait();
    }
public slots:
    void handleResults(const QString &);
signals:
    void operate(const QString &);
};

And it is correct?

Qt::QueuedConnection	- The slot is invoked when control returns to the event loop of the receiver's thread. 
The slot is executed in the receiver's thread.

I think we should add Qt::QueuedConnection to:

        connect(this, &Controller::operate, worker, &Worker::doWork);
        connect(worker, &Worker::resultReady, this, &Controller::handleResults);

I would like to execute doWork() method in other thread, so for me the correct is:

        connect(this, &Controller::operate, worker, &Worker::doWork, Qt::QueuedConnection);
        connect(worker, &Worker::resultReady, this, &Controller::handleResults, Qt::QueuedConnection);

[J.Hilk]

@qwe3 said in Is QThread doc correct?:

And it is correct?

it is.

The default parameter for QObject::Connect() is Qt::AutoConnection, which will be automatically Qt::QeueudConnection if its across threads.

You very rarely need to force a connection type

[qwe3]

@J-Hilk ... Thank you very much! I thought that default is DirectConnection. Thank you! :)

[jsulm]

@qwe3 said in Is QThread doc correct?:

I thought that default is DirectConnection

Take a look at the connect() signature: https://doc.qt.io/qt-5/qobject.html#connect-2