QTextToSpeech: QObject *parent ctor args go last

This is one of the deepest and most long-standing
Qt API design patterns: subclasses add ctor args
_at the front_, not at the back.

To compensate the slight SC breakage, add an
overloaded ctor that only takes QObject *parent
(also a Qt API pattern worth following), so the
common case of

   new QTextToSpeech(this)

continues to work.

Change-Id: I7253abada1355e53e9817914abd80e8af17ce429
Reviewed-by: Lars Knoll <lars.knoll@theqtcompany.com>
Reviewed-by: Jeremy Whiting <jpwhiting@kde.org>
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@theqtcompany.com>

3 files changed, 26 insertions, 4 deletions

diff --git a/examples/speech/hello_speak/mainwindow.cpp b/examples/speech/hello_speak/mainwindow.cpp
index b496cda..6f2f300 100644
--- a/examples/speech/hello_speak/mainwindow.cpp
+++ b/examples/speech/hello_speak/mainwindow.cpp
@@ -103,7 +103,7 @@ void MainWindow::engineSelected(int index)
     if (engineName == "default")
         m_speech = new QTextToSpeech(this);
     else
-        m_speech = new QTextToSpeech(this, engineName);
+        m_speech = new QTextToSpeech(engineName, QVariantMap(), this);
     disconnect(ui.language, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged), this, &MainWindow::languageSelected);
     ui.language->clear();
     // Populate the languages combobox before connecting its signal.
diff --git a/src/tts/qtexttospeech.cpp b/src/tts/qtexttospeech.cpp
index 7157318..0fe752e 100644
--- a/src/tts/qtexttospeech.cpp
+++ b/src/tts/qtexttospeech.cpp
@@ -59,6 +59,7 @@ QTextToSpeechPrivate::QTextToSpeechPrivate(QTextToSpeech *speech, const QString
       m_providerName(engine),
       m_plugin(0)
 {
+    qRegisterMetaType<QTextToSpeech::State>();
     if (m_providerName.isEmpty()) {
         m_providerName = QTextToSpeech::availableEngines().value(0);
         if (m_providerName.isEmpty()) {
@@ -185,6 +186,27 @@ void QTextToSpeechPrivate::loadPluginMetadata(QHash<QString, QJsonObject> &list)
 */
 
 /*!
+    Loads a text-to-speech engine from a plug-in that uses the default
+    engine plug-in and constructs a QTextToSpeech object as the child
+    of \a parent.
+
+    The default engine may be platform-specific.
+
+    If loading the plug-in fails, QTextToSpeech::state() will return
+    QTextToSpeech::BackendError.
+
+    \sa availableEngines()
+*/
+QTextToSpeech::QTextToSpeech(QObject *parent)
+    : QObject(*new QTextToSpeechPrivate(this, QString(), QVariantMap()), parent)
+{
+    Q_D(QTextToSpeech);
+    // Connect state change signal directly from the engine to the public API signal
+    if (d->m_engine)
+        connect(d->m_engine, &QTextToSpeechEngine::stateChanged, this, &QTextToSpeech::stateChanged);
+}
+
+/*!
   Loads a text-to-speech engine from a plug-in that matches parameter \a engine and
   constructs a QTextToSpeech object as the child of \a parent.
 
@@ -197,11 +219,10 @@ void QTextToSpeechPrivate::loadPluginMetadata(QHash<QString, QJsonObject> &list)
 
   \sa availableEngines()
 */
-QTextToSpeech::QTextToSpeech(QObject *parent, const QString &engine, const QVariantMap &parameters)
+QTextToSpeech::QTextToSpeech(const QString &engine, const QVariantMap &parameters, QObject *parent)
     : QObject(*new QTextToSpeechPrivate(this, engine, parameters), parent)
 {
     Q_D(QTextToSpeech);
-    qRegisterMetaType<QTextToSpeech::State>();
     // Connect state change signal directly from the engine to the public API signal
     if (d->m_engine)
         connect(d->m_engine, &QTextToSpeechEngine::stateChanged, this, &QTextToSpeech::stateChanged);
diff --git a/src/tts/qtexttospeech.h b/src/tts/qtexttospeech.h
index bcbe511..bd35c8f 100644
--- a/src/tts/qtexttospeech.h
+++ b/src/tts/qtexttospeech.h
@@ -70,7 +70,8 @@ public:
         BackendError
     };
 
-    explicit QTextToSpeech(QObject *parent = 0, const QString &engine = QString(), const QVariantMap &parameters = QVariantMap());
+    explicit QTextToSpeech(QObject *parent = Q_NULLPTR);
+    explicit QTextToSpeech(const QString &engine, const QVariantMap &parameters = QVariantMap(), QObject *parent = Q_NULLPTR);
     State state() const;
 
     QVector<QLocale> availableLocales() const;