I'm trying to understand the code below (extracted from http://qt-project.org/doc/qt-5/qthread.html).

@
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 &);
};
@

Can someone explain me who/where the operate signal is emitted? Shall I emit operate() signal to launch the thread? If yes, why do I get the following error: Cannot send events to objects owned by a different thread.... ?

Many thanks

[edit: Added missing coding tags @ SGaist]