updated example based on feedback

rm5248 · rm5248 · commit 2d3ebb71e668 · 2019-11-03T11:43:42.000-05:00
diff --git a/examples/qt/README.md b/examples/qt/README.md
@@ -0,0 +1,45 @@
+# libsigc++ with Qt
+
+It is possible to use libsigc++ with Qt.  However, because of the signals/slots
+mechanism of Qt, there is some setup that must be done in order for this to
+happen correctly.
+
+Steps to use libsigc++ with Qt:
+1. In your .pro file, add `CONFIG += no_keywords`.  This configures Qt to not
+define the keywords `emit`, `signals`, and `slot`.
+2. In your header files, change the `signals:` section of your class to instead
+be `Q_SIGNALS`
+3. In your header files, change the `public slots:` section of your class to
+instead be `public Q_SLOTS:`
+4. In any class that you emit a signal, change `emit` to be `Q_EMIT`.
+
+Here's an example of a class before and after this conversion(note: irrelevant
+code has been removed):
+
+```
+class ExampleClass : public QObject {
+signals:
+	void exampleSignal();
+public slots:
+	void example_slot(){
+		emit exampleSignal();
+	}
+};
+```
+
+After conversion:
+```
+class ExampleClass : public QObject {
+Q_SIGNALS:
+	void exampleSignal();
+public Q_SLOTS:
+	void example_slot(){
+		Q_EMIT exampleSignal();
+	}
+};
+```
+
+## Qt Slots Notes
+Since libsigc++ simply requires a slot to be a function, you can call Qt
+slots easily using libsigc++.  Similarly, a function that is a libsigc++ slot
+can also be used as a Qt slot.
diff --git a/examples/qt/exampleclass.cpp b/examples/qt/exampleclass.cpp
@@ -3,30 +3,30 @@
 #include "exampleclass.h"
 
 ExampleClass::ExampleClass(QObject *parent) :
-    QObject(parent),
-    m_times(0)
+    QObject(parent)
 {
     /* Create a slot from our example_slot method. */
-    m_slot = sigc::mem_fun( *this, &ExampleClass::example_slot );
+    m_sigc_slot = sigc::mem_fun( *this, &ExampleClass::example_slot );
 
+    /* Connect our sigc++ signal to our sigc++ slot */
+    m_sigc_signal.connect( m_sigc_slot );
+
+    /* Emit a sigc++ signal */
+    m_sigc_signal.emit();
+
+    /* Connect the Qt signal to our Qt slot */
     connect( &m_timer, &QTimer::timeout,
              this, &ExampleClass::timer_slot );
     m_timer.start( 200 );
+
+    /* Emit a Qt signal */
+    Q_EMIT example_signal();
 }
 
 void ExampleClass::timer_slot(){
     qDebug() << "Timer slot called";
 
-    /* Call the slot that is used by libsigc++ */
-    m_slot();
-
-    /* Emit a Qt signal */
-    Q_EMIT example_signal();
-
-    /* Only run for a few times before exiting */
-    if( m_times++ > 10 ){
-        QCoreApplication::exit( 0 );
-    }
+    QCoreApplication::exit( 0 );
 }
 
 void ExampleClass::example_slot(){
diff --git a/examples/qt/exampleclass.h b/examples/qt/exampleclass.h
@@ -28,9 +28,9 @@ public Q_SLOTS:
     void example_slot();
 
 private:
-    sigc::slot<void()> m_slot;
+    sigc::slot<void()> m_sigc_slot;
+    sigc::signal<void()> m_sigc_signal;
     QTimer m_timer;
-    int m_times;
 };
 
 #endif // EXAMPLECLASS_H
