Thermostat: MQTTClient: switch to a singleton

soft/thermostat/inc/mainwindow.h

@@ -34,8 +34,6 @@ public:
 	explicit MainWindow(QWidget *parent = NULL);
 	~MainWindow();
 
-	MQTTClient *mqttclient;
-
 private:
 	QPushButton m_state_btn;
 	BackgroundLoop m_backLoop;

soft/thermostat/inc/mqttclient.h

@@ -18,13 +18,15 @@ class MQTTClient: public QMQTT::Client
 {
 	Q_OBJECT
 public:
+	void publish_msg(const QString& topic, const QString& payload);
+	static MQTTClient *getInstance(void);
+
+private:
 	explicit MQTTClient(const QHostAddress& host = QHostAddress::LocalHost,
 			       const quint16 port = 1883,
 			       QObject* parent = NULL);
 	virtual ~MQTTClient();
-	void publish_msg(const QString& topic, const QString& payload);
-
-private:
+	static MQTTClient *_singleton;
 	QTimer m_timer;
 
 public slots:

soft/thermostat/src/mainwindow.cpp

@@ -21,10 +21,8 @@ MainWindow::MainWindow(QWidget *parent) :
 	QMainWindow(parent)
 {
 	ZoneItem *zone;
-
 	Settings *s = Settings::getInstance();
-
-	mqttclient = new MQTTClient(QHostAddress(s->m_broker.address), s->m_broker.port);
+	MQTTClient *mqttclient = MQTTClient::getInstance();
 
 	for (int i = 0; i < s->nbZones(); i++) {
 		zone = new ZoneItem(s->m_rooms.at(i).name, this);
@@ -69,8 +67,6 @@ MainWindow::MainWindow(QWidget *parent) :
 	setWindowTitle(tr("Sorico's thermostat"));
 	m_backLoop.start();
 
-	mqttclient->connectToHost();
-
 	connect(&m_state_btn, SIGNAL(clicked()), this, SLOT(change_state()));
 }
 

soft/thermostat/src/mqttclient.cpp

@@ -16,6 +16,19 @@
 #include "settings.h"
 #include "qmqtt.h"
 
+MQTTClient *MQTTClient::_singleton = NULL;
+
+MQTTClient *MQTTClient::getInstance(void)
+{
+	if (!_singleton) {
+		Settings *s = Settings::getInstance();
+
+		_singleton =  new MQTTClient(QHostAddress(s->m_broker.address), s->m_broker.port);
+	}
+
+	return _singleton;
+}
+
 MQTTClient::MQTTClient(const QHostAddress& host, const quint16 port,
 			     QObject* parent) : QMQTT::Client(host, port, parent)
 {
@@ -24,7 +37,8 @@ MQTTClient::MQTTClient(const QHostAddress& host, const quint16 port,
 	connect(this, &MQTTClient::received, this, &MQTTClient::onReceived);
 	connect(this, &MQTTClient::published, this, &MQTTClient::onPublished);
 	connect(this, &MQTTClient::error, this, &MQTTClient::onError);
-	qDebug() << "created" << endl;
+
+	connectToHost();
 }
 
 MQTTClient::~MQTTClient() {