Doc: Update QThread class ref to reflect changes since Qt 4.4

Remove advice to subclass QThread; promote thinking of QThread as a
thread manager, not a thread; promote event-driven programming over time
micromanagement; warn against common pitfalls.

Result of collaboration in forum (https://qt-project.org/forums/viewthread/20691/)
and mailing list (http://lists.qt-project.org/pipermail/development/2012-September/006738.html)

This is a modified backport of
qtbase commit d4ad9dbbf96884c0899e8f8116a8a056facd52d5

Task-number: QTBUG-16358
Change-Id: Ib7a8d40aa418b1d96e3e7070df074b396ae9ee7e
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@digia.com>

1 files changed, 31 insertions, 9 deletions

diff --git a/doc/src/snippets/code/src_corelib_thread_qthread.cpp b/doc/src/snippets/code/src_corelib_thread_qthread.cpp
index 420f035..1a07744 100644
--- a/doc/src/snippets/code/src_corelib_thread_qthread.cpp
+++ b/doc/src/snippets/code/src_corelib_thread_qthread.cpp
@@ -39,18 +39,40 @@
 ****************************************************************************/
 
 //! [0]
-class MyThread : public QThread
+class Worker : public QObject
 {
-public:
-    void run();
+    Q_OBJECT
+
+public slots:
+    void doWork() {
+        ...
+    }
 };
 
-void MyThread::run()
+void MyObject::putWorkerInAThread()
 {
-    QTcpSocket socket;
-    // connect QTcpSocket's signals somewhere meaningful
-    ...
-    socket.connectToHost(hostName, portNumber);
-    exec();
+    Worker *worker = new Worker;
+    QThread *workerThread = new QThread(this);
+
+    connect(workerThread, SIGNAL(started()), worker, SLOT(doWork()));
+    connect(workerThread, SIGNAL(finished()), worker, SLOT(deleteLater()));
+    worker->moveToThread(workerThread);
+
+    // Starts an event loop, and emits workerThread->started()
+    workerThread->start();
 }
 //! [0]
+
+//! [1]
+class AdvancedThreadManager : public QThread
+{
+protected:
+    void run()
+    {
+        /* ... other code to initialize thread... */
+
+        // Begin event handling
+        exec();
+    }
+};
+//! [1]