examples: Use QOverload to select overloaded signals and slots

We can use QOverload since Qt 5.7 (it depends on Q_COMPILER_VARIADIC_TEMPLATES
which is required since Qt 5.7).
Use it in the examples to show the best practice.
qOverload currently can't be used because it requires c++14.

Change-Id: I94a3c0db9d551fe169fa3d19c07ec0b329d5946c
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

examples/network/fortuneclient/client.cpp

@@ -122,8 +122,7 @@ Client::Client(QWidget *parent)
 //! [2] //! [3]
     connect(tcpSocket, &QIODevice::readyRead, this, &Client::readFortune);
 //! [2] //! [4]
-    typedef void (QAbstractSocket::*QAbstractSocketErrorSignal)(QAbstractSocket::SocketError);
+    connect(tcpSocket, QOverload<QAbstractSocket::SocketError>::of(&QAbstractSocket::error),
-    connect(tcpSocket, static_cast<QAbstractSocketErrorSignal>(&QAbstractSocket::error),
 //! [3]
             this, &Client::displayError);
 //! [4]

examples/opengl/paintedwindow/paintedwindow.cpp

@@ -95,9 +95,7 @@ PaintedWindow::PaintedWindow()
 
     connect(screen(), &QScreen::orientationChanged, this, &PaintedWindow::orientationChanged);
     connect(m_animation, &QAbstractAnimation::finished, this, &PaintedWindow::rotationDone);
-    typedef void (PaintedWindow::*PaintedWindowVoidSlot)();
+    connect(this, &PaintedWindow::rotationChanged, this, QOverload<>::of(&PaintedWindow::paint));
-    connect(this, &PaintedWindow::rotationChanged,
-            this, static_cast<PaintedWindowVoidSlot>(&PaintedWindow::paint));
 }
 
 void PaintedWindow::exposeEvent(QExposeEvent *)

examples/opengl/qopenglwidget/mainwindow.cpp

@@ -61,8 +61,6 @@
 
 #include "glwidget.h"
 
-typedef void (QWidget::*QWidgetVoidSlot)();
-
 MainWindow::MainWindow()
     : m_nextX(1), m_nextY(1)
 {
@@ -131,14 +129,11 @@ MainWindow::MainWindow()
     QMenu *helpMenu = menuBar()->addMenu("&Help");
     helpMenu->addAction("About Qt", qApp, &QApplication::aboutQt);
 
-    connect(m_timer, &QTimer::timeout,
+    connect(m_timer, &QTimer::timeout, glwidget, QOverload<>::of(&QWidget::update));
-            glwidget, static_cast<QWidgetVoidSlot>(&QWidget::update));
 
     connect(slider, &QAbstractSlider::valueChanged, glwidget, &GLWidget::setScaling);
     connect(transparent, &QCheckBox::toggled, glwidget, &GLWidget::setTransparent);
-
+    connect(updateInterval, QOverload<int>::of(&QSpinBox::valueChanged),
-    typedef void (QSpinBox::*QSpinBoxIntSignal)(int);
-    connect(updateInterval, static_cast<QSpinBoxIntSignal>(&QSpinBox::valueChanged),
             this, &MainWindow::updateIntervalChanged);
     connect(timerBased, &QCheckBox::toggled, this, &MainWindow::timerUsageChanged);
     connect(timerBased, &QCheckBox::toggled, updateInterval, &QWidget::setEnabled);
@@ -162,7 +157,7 @@ void MainWindow::addNew()
         return;
     GLWidget *w = new GLWidget(this, false, qRgb(qrand() % 256, qrand() % 256, qrand() % 256));
     m_glWidgets << w;
-    connect(m_timer, &QTimer::timeout, w, static_cast<QWidgetVoidSlot>(&QWidget::update));
+    connect(m_timer, &QTimer::timeout, w, QOverload<>::of(&QWidget::update));
     m_layout->addWidget(w, m_nextY, m_nextX, 1, 1);
     if (m_nextX == 3) {
         m_nextX = 1;

examples/opengl/qopenglwindow/main.cpp

@@ -173,8 +173,6 @@ void OpenGLWindow::keyPressEvent(QKeyEvent *e)
 
 void OpenGLWindow::setAnimating(bool enabled)
 {
-    typedef void (QPaintDeviceWindow::*QPaintDeviceWindowVoidSlot)();
-
     if (enabled) {
         // Animate continuously, throttled by the blocking swapBuffers() call the
         // QOpenGLWindow internally executes after each paint. Once that is done
@@ -182,11 +180,11 @@ void OpenGLWindow::setAnimating(bool enabled)
         // obviously assumes that the swap interval (see
         // QSurfaceFormat::setSwapInterval()) is non-zero.
         connect(this, &QOpenGLWindow::frameSwapped,
-                this, static_cast<QPaintDeviceWindowVoidSlot>(&QPaintDeviceWindow::update));
+                this, QOverload<>::of(&QPaintDeviceWindow::update));
         update();
     } else {
         disconnect(this, &QOpenGLWindow::frameSwapped,
-                   this, static_cast<QPaintDeviceWindowVoidSlot>(&QPaintDeviceWindow::update));
+                   this, QOverload<>::of(&QPaintDeviceWindow::update));
     }
 }
 

examples/widgets/desktop/screenshot/screenshot.cpp

@@ -70,8 +70,7 @@ Screenshot::Screenshot()
     delaySpinBox->setSuffix(tr(" s"));
     delaySpinBox->setMaximum(60);
 
-    typedef void (QSpinBox::*QSpinBoxIntSignal)(int);
+    connect(delaySpinBox, QOverload<int>::of(&QSpinBox::valueChanged),
-    connect(delaySpinBox, static_cast<QSpinBoxIntSignal>(&QSpinBox::valueChanged),
             this, &Screenshot::updateCheckBox);
 
     hideThisWindowCheckBox = new QCheckBox(tr("Hide This Window"), optionsGroupBox);

examples/widgets/desktop/systray/window.cpp

@@ -80,8 +80,7 @@ Window::Window()
 
     connect(showMessageButton, &QAbstractButton::clicked, this, &Window::showMessage);
     connect(showIconCheckBox, &QAbstractButton::toggled, trayIcon, &QSystemTrayIcon::setVisible);
-    typedef void (QComboBox::*QComboIntSignal)(int);
+    connect(iconComboBox, QOverload<int>::of(&QComboBox::currentIndexChanged),
-    connect(iconComboBox, static_cast<QComboIntSignal>(&QComboBox::currentIndexChanged),
             this, &Window::setIcon);
     connect(trayIcon, &QSystemTrayIcon::messageClicked, this, &Window::messageClicked);
     connect(trayIcon, &QSystemTrayIcon::activated, this, &Window::iconActivated);

examples/widgets/itemviews/basicsortfiltermodel/window.cpp

@@ -89,11 +89,9 @@ Window::Window()
 
     connect(filterPatternLineEdit, &QLineEdit::textChanged,
             this, &Window::filterRegExpChanged);
-
+    connect(filterSyntaxComboBox, QOverload<int>::of(&QComboBox::currentIndexChanged),
-    typedef void (QComboBox::*QComboIntSignal)(int);
-    connect(filterSyntaxComboBox, static_cast<QComboIntSignal>(&QComboBox::currentIndexChanged),
             this, &Window::filterRegExpChanged);
-    connect(filterColumnComboBox, static_cast<QComboIntSignal>(&QComboBox::currentIndexChanged),
+    connect(filterColumnComboBox, QOverload<int>::of(&QComboBox::currentIndexChanged),
             this, &Window::filterColumnChanged);
     connect(filterCaseSensitivityCheckBox, &QAbstractButton::toggled,
             this, &Window::filterRegExpChanged);

examples/widgets/itemviews/pixelator/mainwindow.cpp

@@ -113,10 +113,9 @@ MainWindow::MainWindow()
     connect(quitAction, &QAction::triggered, qApp, &QCoreApplication::quit);
     connect(aboutAction, &QAction::triggered, this, &MainWindow::showAboutBox);
 //! [4]
-    typedef void (QSpinBox::*QSpinBoxIntSignal)(int);
+    connect(pixelSizeSpinBox, QOverload<int>::of(&QSpinBox::valueChanged),
-    connect(pixelSizeSpinBox, static_cast<QSpinBoxIntSignal>(&QSpinBox::valueChanged),
             delegate, &PixelDelegate::setPixelSize);
-    connect(pixelSizeSpinBox, static_cast<QSpinBoxIntSignal>(&QSpinBox::valueChanged),
+    connect(pixelSizeSpinBox, QOverload<int>::of(&QSpinBox::valueChanged),
             this, &MainWindow::updateView);
 //! [4]
 

examples/widgets/richtext/textedit/textedit.cpp

@@ -342,13 +342,11 @@ void TextEdit::setupTextActions()
     comboStyle->addItem("Ordered List (Roman lower)");
     comboStyle->addItem("Ordered List (Roman upper)");
 
-    typedef void (QComboBox::*QComboIntSignal)(int);
+    connect(comboStyle, QOverload<int>::of(&QComboBox::activated), this, &TextEdit::textStyle);
-    connect(comboStyle, static_cast<QComboIntSignal>(&QComboBox::activated), this, &TextEdit::textStyle);
 
-    typedef void (QComboBox::*QComboStringSignal)(const QString &);
     comboFont = new QFontComboBox(tb);
     tb->addWidget(comboFont);
-    connect(comboFont, static_cast<QComboStringSignal>(&QComboBox::activated), this, &TextEdit::textFamily);
+    connect(comboFont, QOverload<const QString &>::of(&QComboBox::activated), this, &TextEdit::textFamily);
 
     comboSize = new QComboBox(tb);
     comboSize->setObjectName("comboSize");
@@ -360,7 +358,7 @@ void TextEdit::setupTextActions()
         comboSize->addItem(QString::number(size));
     comboSize->setCurrentIndex(standardSizes.indexOf(QApplication::font().pointSize()));
 
-    connect(comboSize, static_cast<QComboStringSignal>(&QComboBox::activated), this, &TextEdit::textSize);
+    connect(comboSize, QOverload<const QString &>::of(&QComboBox::activated), this, &TextEdit::textSize);
 }
 
 bool TextEdit::load(const QString &f)

examples/widgets/tools/codecs/previewform.cpp

@@ -159,8 +159,7 @@ PreviewForm::PreviewForm(QWidget *parent)
         new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel);
     okButton = buttonBox->button(QDialogButtonBox::Ok);
 
-    typedef void(QComboBox::*ComboBoxIntSignal)(int);
+    connect(encodingComboBox, QOverload<int>::of(&QComboBox::activated),
-    connect(encodingComboBox, static_cast<ComboBoxIntSignal>(&QComboBox::activated),
             this, &PreviewForm::updateTextEdit);
     connect(buttonBox, &QDialogButtonBox::accepted, this, &QDialog::accept);
     connect(buttonBox, &QDialogButtonBox::rejected, this, &QDialog::reject);

examples/widgets/tools/regularexpression/regularexpressiondialog.cpp

@@ -94,10 +94,10 @@ RegularExpressionDialog::RegularExpressionDialog(QWidget *parent)
     connect(optimizeOnFirstUsageOptionCheckBox, &QCheckBox::toggled, this, &RegularExpressionDialog::refresh);
     connect(dontAutomaticallyOptimizeOptionCheckBox, &QCheckBox::toggled, this, &RegularExpressionDialog::refresh);
 
-    connect(offsetSpinBox, static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged),
+    connect(offsetSpinBox, QOverload<int>::of(&QSpinBox::valueChanged),
             this, &RegularExpressionDialog::refresh);
 
-    connect(matchTypeComboBox, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged),
+    connect(matchTypeComboBox, QOverload<int>::of(&QComboBox::currentIndexChanged),
             this, &RegularExpressionDialog::refresh);
 
     connect(anchoredMatchOptionCheckBox, &QCheckBox::toggled, this, &RegularExpressionDialog::refresh);

examples/widgets/tools/settingseditor/locationdialog.cpp

@@ -106,10 +106,9 @@ LocationDialog::LocationDialog(QWidget *parent)
 
     buttonBox = new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel);
 
-    typedef void (QComboBox::*QComboIntSignal)(int);
+    connect(formatComboBox, QOverload<int>::of(&QComboBox::activated),
-    connect(formatComboBox, static_cast<QComboIntSignal>(&QComboBox::activated),
             this, &LocationDialog::updateLocationsTable);
-    connect(scopeComboBox, static_cast<QComboIntSignal>(&QComboBox::activated),
+    connect(scopeComboBox, QOverload<int>::of(&QComboBox::activated),
             this, &LocationDialog::updateLocationsTable);
     connect(organizationComboBox->lineEdit(),
             &QLineEdit::editingFinished,
@@ -117,7 +116,7 @@ LocationDialog::LocationDialog(QWidget *parent)
     connect(applicationComboBox->lineEdit(),
             &QLineEdit::editingFinished,
             this, &LocationDialog::updateLocationsTable);
-    connect(applicationComboBox, static_cast<QComboIntSignal>(&QComboBox::activated),
+    connect(applicationComboBox, QOverload<int>::of(&QComboBox::activated),
             this, &LocationDialog::updateLocationsTable);
     connect(buttonBox, &QDialogButtonBox::accepted, this, &QDialog::accept);
     connect(buttonBox, &QDialogButtonBox::rejected, this, &QDialog::reject);

examples/widgets/widgets/charactermap/mainwindow.cpp

@@ -74,8 +74,7 @@ MainWindow::MainWindow()
     filterCombo->addItem(tr("Monospaced"), QVariant::fromValue(QFontComboBox::MonospacedFonts));
     filterCombo->addItem(tr("Proportional"), QVariant::fromValue(QFontComboBox::ProportionalFonts));
     filterCombo->setCurrentIndex(0);
-    typedef void (QComboBox::*QComboBoxIntSignal)(int);
+    connect(filterCombo, QOverload<int>::of(&QComboBox::currentIndexChanged),
-    connect(filterCombo, static_cast<QComboBoxIntSignal>(&QComboBox::currentIndexChanged),
             this, &MainWindow::filterChanged);
 
     QLabel *fontLabel = new QLabel(tr("Font:"));
@@ -114,10 +113,9 @@ MainWindow::MainWindow()
             this, &MainWindow::findSizes);
     connect(fontCombo, &QFontComboBox::currentFontChanged,
             characterWidget, &CharacterWidget::updateFont);
-    typedef void (QComboBox::*QComboBoxStringSignal)(const QString &);
+    connect(sizeCombo, QOverload<const QString &>::of(&QComboBox::currentIndexChanged),
-    connect(sizeCombo, static_cast<QComboBoxStringSignal>(&QComboBox::currentIndexChanged),
             characterWidget, &CharacterWidget::updateSize);
-    connect(styleCombo, static_cast<QComboBoxStringSignal>(&QComboBox::currentIndexChanged),
+    connect(styleCombo, QOverload<const QString &>::of(&QComboBox::currentIndexChanged),
             characterWidget, &CharacterWidget::updateStyle);
 //! [4] //! [5]
     connect(characterWidget, &CharacterWidget::characterSelected,

examples/widgets/widgets/icons/imagedelegate.cpp

@@ -71,8 +71,7 @@ QWidget *ImageDelegate::createEditor(QWidget *parent,
     else if (index.column() == 2)
         comboBox->addItems(IconPreviewArea::iconStateNames());
 
-    typedef void (QComboBox::*QComboBoxIntSignal)(int);
+    connect(comboBox, QOverload<int>::of(&QComboBox::activated),
-    connect(comboBox, static_cast<QComboBoxIntSignal>(&QComboBox::activated),
             this, &ImageDelegate::emitCommitData);
 
     return comboBox;

examples/widgets/widgets/icons/mainwindow.cpp

@@ -362,8 +362,7 @@ QWidget *MainWindow::createIconSizeGroupBox()
     sizeButtonGroup = new QButtonGroup(this);
     sizeButtonGroup->setExclusive(true);
 
-    typedef void (QButtonGroup::*QButtonGroupIntBoolSignal)(int, bool);
+    connect(sizeButtonGroup, QOverload<int, bool>::of(&QButtonGroup::buttonToggled),
-    connect(sizeButtonGroup, static_cast<QButtonGroupIntBoolSignal>(&QButtonGroup::buttonToggled),
             this, &MainWindow::changeSize);
 
     QRadioButton *smallRadioButton = new QRadioButton;
@@ -391,8 +390,7 @@ QWidget *MainWindow::createIconSizeGroupBox()
 //! [26]
 
 //! [27]
-    typedef void (QSpinBox::*QSpinBoxIntSignal)(int);
+    connect(otherSpinBox, QOverload<int>::of(&QSpinBox::valueChanged),
-    connect(otherSpinBox, static_cast<QSpinBoxIntSignal>(&QSpinBox::valueChanged),
             this, &MainWindow::triggerChangeSize);
 
     QHBoxLayout *otherSizeLayout = new QHBoxLayout;