Revert the singleton PR

It turns out that this isn't working the way it was intended to.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

core/btdiscovery.cpp

@@ -15,6 +15,7 @@ extern QMap<QString, dc_descriptor_t *> descriptorLookup;
 namespace {
 	QHash<QString, QBluetoothDeviceInfo> btDeviceInfo;
 }
+BTDiscovery *BTDiscovery::m_instance = NULL;
 
 static dc_descriptor_t *getDeviceType(QString btName)
 // central function to convert a BT name to a Subsurface known vendor/model pair
@@ -138,6 +139,11 @@ BTDiscovery::BTDiscovery(QObject*) : m_btValid(false),
 	m_showNonDiveComputers(false),
 	discoveryAgent(nullptr)
 {
+	if (m_instance) {
+		qDebug() << "trying to create an additional BTDiscovery object";
+		return;
+	}
+	m_instance = this;
 #if defined(BT_SUPPORT)
 	QLoggingCategory::setFilterRules(QStringLiteral("qt.bluetooth* = true"));
 	BTDiscoveryReDiscover();
@@ -196,11 +202,19 @@ void BTDiscovery::BTDiscoveryReDiscover()
 
 BTDiscovery::~BTDiscovery()
 {
+	m_instance = NULL;
 #if defined(BT_SUPPORT)
 	delete discoveryAgent;
 #endif
 }
 
+BTDiscovery *BTDiscovery::instance()
+{
+	if (!m_instance)
+		m_instance = new BTDiscovery();
+	return m_instance;
+}
+
 #if defined(BT_SUPPORT)
 extern void addBtUuid(QBluetoothUuid uuid);
 extern QHash<QString, QStringList> productList;

core/btdiscovery.h

@@ -10,7 +10,6 @@
 #include <QBluetoothDeviceDiscoveryAgent>
 #include <QBluetoothUuid>
 #include "core/libdivecomputer.h"
-#include "core/singleton.h"
 
 #if defined(Q_OS_ANDROID)
 #include <QAndroidJniObject>
@@ -24,12 +23,13 @@ QString extractBluetoothAddress(const QString &address);
 QString extractBluetoothNameAddress(const QString &address, QString &name);
 QBluetoothDeviceInfo getBtDeviceInfo(const QString &devaddr);
 
-class BTDiscovery : public QObject, public SillySingleton<BTDiscovery> {
+class BTDiscovery : public QObject {
 	Q_OBJECT
 
 public:
 	BTDiscovery(QObject *parent = NULL);
 	~BTDiscovery();
+	static BTDiscovery *instance();
 
 	struct btPairedDevice {
 		QString address;
@@ -57,6 +57,7 @@ public:
 	void discoverAddress(QString address);
 
 private:
+	static BTDiscovery *m_instance;
 	bool m_btValid;
 	bool m_showNonDiveComputers;
 

core/gpslocation.cpp

@@ -15,12 +15,16 @@
 #include <QApplication>
 #include <QTimer>
 
+GpsLocation *GpsLocation::m_Instance = NULL;
+
 GpsLocation::GpsLocation(void (*showMsgCB)(const char *), QObject *parent) :
 	QObject(parent),
 	m_GpsSource(0),
 	waitingForPosition(false),
 	haveSource(UNKNOWN)
 {
+	Q_ASSERT_X(m_Instance == NULL, "GpsLocation", "GpsLocation recreated");
+	m_Instance = this;
 	showMessageCB = showMsgCB;
 	// create a QSettings object that's separate from the main application settings
 	geoSettings = new QSettings(QSettings::NativeFormat, QSettings::UserScope,
@@ -33,6 +37,23 @@ GpsLocation::GpsLocation(void (*showMsgCB)(const char *), QObject *parent) :
 	connect(qPrefLocationService::instance(), SIGNAL(time_thresholdChanged(int)), this, SLOT(setGpsTimeThreshold(int)));
 }
 
+GpsLocation *GpsLocation::instance()
+{
+	Q_ASSERT(m_Instance != NULL);
+
+	return m_Instance;
+}
+
+bool GpsLocation::hasInstance()
+{
+	return m_Instance != NULL;
+}
+
+GpsLocation::~GpsLocation()
+{
+	m_Instance = NULL;
+}
+
 void GpsLocation::setGpsTimeThreshold(int seconds)
 {
 	if (m_GpsSource) {

core/gpslocation.h

@@ -24,6 +24,9 @@ class GpsLocation : public QObject {
 	Q_OBJECT
 public:
 	GpsLocation(void (*showMsgCB)(const char *msg), QObject *parent);
+	~GpsLocation();
+	static GpsLocation *instance();
+	static bool hasInstance();
 	bool applyLocations();
 	int getGpsNum() const;
 	bool hasLocationsSource();
@@ -40,6 +43,7 @@ private:
 	QNetworkReply *reply;
 	QString userAgent;
 	void (*showMessageCB)(const char *msg);
+	static GpsLocation *m_Instance;
 	bool waitingForPosition;
 	QMap<qint64, gpsTracker> m_trackers;
 	QList<gpsTracker> m_deletedTrackers;

core/singleton.h

@@ -1,74 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * We use singletons in numerous places. In combination with QML this gives
- * us a very fundamental problem, because QML likes to allocate objects by
- * itself. There are known workarounds, but currently we use idiosyncratic
- * singleton classes, which initialize the global instance pointer in the
- * constructor. Things get even more complicated if the same singleton is used
- * on mobile and on desktop. The latter might want to simply use the classical
- * instance() function without having to initialize the singleton first, as
- * that would beat the purpose of the instance() method.
- *
- * The template defined here, SillySingleton, codifies all this. Simply derive
- * a class from this template:
- *	class X : public SillySingleton<X> {
- *		...
- *	};
- * This will generate an instance() method. This will do the right thing for
- * both methods: explicit construction of the singleton via new or implicit
- * by calling the instance() method. It will also generate warnings if a
- * singleton class is generated more than once (i.e. first instance() is called
- * and _then_ new).
- *
- * In the long run we should get rid of all users of this class.
- */
-#ifndef SINGLETON_H
-#define SINGLETON_H
-
-#include <typeinfo>
-#include <QtGlobal>
-
-// 1) Declaration
-template<typename T>
-class SillySingleton {
-	static T *self;
-protected:
-	SillySingleton();
-	~SillySingleton();
-public:
-	static T *instance();
-};
-
-template<typename T>
-T *SillySingleton<T>::self = nullptr;
-
-// 2) Implementation
-
-template<typename T>
-SillySingleton<T>::SillySingleton()
-{
-	if (self)
-		qWarning("Generating second instance of singleton %s", typeid(T).name());
-	self = static_cast<T *>(this);
-	qDebug("Generated singleton %s", typeid(T).name());
-}
-
-template<typename T>
-SillySingleton<T>::~SillySingleton()
-{
-	if (self == this)
-		self = nullptr;
-	else
-		qWarning("Destroying unknown instance of singleton %s", typeid(T).name());
-	qDebug("Destroyed singleton %s", typeid(T).name());
-}
-
-template<typename T>
-T *SillySingleton<T>::instance()
-{
-	if (!self)
-		new T;
-	return self;
-}
-
-#endif

desktop-widgets/mainwindow.cpp

@@ -109,6 +109,8 @@ extern "C" int updateProgress(const char *text)
 	return progressDialogCanceled;
 }
 
+MainWindow *MainWindow::m_Instance = nullptr;
+
 extern "C" void showErrorFromC(char *buf)
 {
 	QString error(buf);
@@ -126,6 +128,8 @@ MainWindow::MainWindow() : QMainWindow(),
 	survey(nullptr),
 	findMovedImagesDialog(nullptr)
 {
+	Q_ASSERT_X(m_Instance == NULL, "MainWindow", "MainWindow recreated!");
+	m_Instance = this;
 	ui.setupUi(this);
 	read_hashes();
 	Command::init();
@@ -353,6 +357,7 @@ MainWindow::MainWindow() : QMainWindow(),
 MainWindow::~MainWindow()
 {
 	write_hashes();
+	m_Instance = nullptr;
 }
 
 void MainWindow::setupSocialNetworkMenu()
@@ -393,6 +398,11 @@ void MainWindow::setDefaultState()
 		ui.bottomLeft->currentWidget()->setEnabled(false);
 }
 
+MainWindow *MainWindow::instance()
+{
+	return m_Instance;
+}
+
 // This gets called after one or more dives were added, edited or downloaded for a dive computer
 void MainWindow::refreshDisplay(bool doRecreateDiveList)
 {

desktop-widgets/mainwindow.h

@@ -21,7 +21,6 @@
 #include "desktop-widgets/filterwidget2.h"
 #include "core/applicationstate.h"
 #include "core/gpslocation.h"
-#include "core/singleton.h"
 
 #define NUM_RECENT_FILES 4
 
@@ -43,7 +42,7 @@ class LocationInformationWidget;
 typedef std::pair<QByteArray, QVariant> WidgetProperty;
 typedef QVector<WidgetProperty> PropertyList;
 
-class MainWindow : public QMainWindow, public SillySingleton<MainWindow> {
+class MainWindow : public QMainWindow {
 	Q_OBJECT
 public:
 	enum {
@@ -62,6 +61,7 @@ public:
 
 	MainWindow();
 	~MainWindow();
+	static MainWindow *instance();
 	void loadRecentFiles();
 	void updateRecentFiles();
 	void updateRecentFilesMenu();
@@ -193,6 +193,7 @@ private:
 	QString filter_open();
 	QString filter_import();
 	QString filter_import_dive_sites();
+	static MainWindow *m_Instance;
 	QString displayedFilename(QString fullFilename);
 	bool askSaveChanges();
 	bool okToClose(QString message);

mobile-widgets/qmlmanager.cpp

@@ -44,6 +44,7 @@
 #include "core/settings/qPrefUnit.h"
 #include "core/trip.h"
 
+QMLManager *QMLManager::m_instance = NULL;
 bool noCloudToCloud = false;
 
 #define RED_FONT QLatin1Literal("<font color=\"red\">")
@@ -149,6 +150,7 @@ QMLManager::QMLManager() : m_locationServiceEnabled(false),
 	m_showNonDiveComputers(false)
 {
 	LOG_STP("qmlmgr starting");
+	m_instance = this;
 	m_lastDevicePixelRatio = qApp->devicePixelRatio();
 	timer.start();
 	connect(qobject_cast<QApplication *>(QApplication::instance()), &QApplication::applicationStateChanged, this, &QMLManager::applicationStateChanged);
@@ -449,6 +451,12 @@ QMLManager::~QMLManager()
 	if (appLogFileOpen)
 		appLogFile.close();
 #endif
+	m_instance = NULL;
+}
+
+QMLManager *QMLManager::instance()
+{
+	return m_instance;
 }
 
 #define CLOUDURL QString(prefs.cloud_base_url)
@@ -1556,7 +1564,7 @@ void QMLManager::applyGpsData()
 void QMLManager::populateGpsData()
 {
 	if (GpsListModel::instance())
-		GpsListModel::instance()->update(QVector<gpsTracker>::fromList(locationProvider->currentGPSInfo().values()));
+		GpsListModel::instance()->update();
 }
 
 void QMLManager::clearGpsData()

mobile-widgets/qmlmanager.h

@@ -13,14 +13,13 @@
 #include "core/btdiscovery.h"
 #include "core/gpslocation.h"
 #include "core/downloadfromdcthread.h"
-#include "core/singleton.h"
 #include "qt-models/divelistmodel.h"
 #include "qt-models/completionmodels.h"
 #include "qt-models/divelocationmodel.h"
 
 #define NOCLOUD_LOCALSTORAGE format_string("%s/cloudstorage/localrepo[master]", system_default_directory())
 
-class QMLManager : public QObject, public SillySingleton<QMLManager> {
+class QMLManager : public QObject {
 	Q_OBJECT
 	Q_PROPERTY(QString logText READ logText WRITE setLogText NOTIFY logTextChanged)
 	Q_PROPERTY(bool locationServiceEnabled MEMBER m_locationServiceEnabled WRITE setLocationServiceEnabled NOTIFY locationServiceEnabledChanged)
@@ -90,6 +89,7 @@ public:
 	Q_INVOKABLE void setGitLocalOnly(const bool &value);
 	Q_INVOKABLE void setFilter(const QString filterText);
 
+	static QMLManager *instance();
 	Q_INVOKABLE void registerError(QString error);
 	QString consumeError();
 
@@ -219,6 +219,7 @@ private:
 	bool m_verboseEnabled;
 	GpsLocation *locationProvider;
 	bool m_loadFromCloud;
+	static QMLManager *m_instance;
 	struct dive *deletedDive;
 	struct dive_trip *deletedTrip;
 	QString m_notificationText;

mobile-widgets/qmlprefs.cpp

@@ -8,13 +8,30 @@
 
 
 /*** Global and constructors ***/
+QMLPrefs *QMLPrefs::m_instance = NULL;
+
 QMLPrefs::QMLPrefs() :
 	m_credentialStatus(qPrefCloudStorage::CS_UNKNOWN),
 	m_oldStatus(qPrefCloudStorage::CS_UNKNOWN),
 	m_showPin(false)
 {
+	// This strange construct is needed because QMLEngine calls new and that
+	// cannot be overwritten
+	if (!m_instance)
+		m_instance = this;
 }
 
+QMLPrefs::~QMLPrefs()
+{
+	m_instance = NULL;
+}
+
+QMLPrefs *QMLPrefs::instance()
+{
+	return m_instance;
+}
+
+
 /*** public functions ***/
 const QString QMLPrefs::cloudPassword() const
 {

mobile-widgets/qmlprefs.h

@@ -5,9 +5,9 @@
 #include <QObject>
 #include "core/settings/qPrefCloudStorage.h"
 #include "core/settings/qPrefDisplay.h"
-#include "core/singleton.h"
 
-class QMLPrefs : public QObject, public SillySingleton<QMLPrefs> {
+
+class QMLPrefs : public QObject {
 	Q_OBJECT
 	Q_PROPERTY(QString cloudPassword
 				MEMBER m_cloudPassword
@@ -35,6 +35,9 @@ class QMLPrefs : public QObject, public SillySingleton<QMLPrefs> {
 				NOTIFY oldStatusChanged)
 public:
 	QMLPrefs();
+	~QMLPrefs();
+
+	static QMLPrefs *instance();
 
 	const QString cloudPassword() const;
 	void setCloudPassword(const QString &cloudPassword);
@@ -63,6 +66,7 @@ private:
 	QString m_cloudPin;
 	QString m_cloudUserName;
 	qPrefCloudStorage::cloud_status m_credentialStatus;
+	static QMLPrefs *m_instance;
 	qPrefCloudStorage::cloud_status m_oldStatus;
 	bool m_showPin;
 

qt-models/divelistmodel.cpp

@@ -134,8 +134,11 @@ QString DiveListSortModel::tripShortDate(const QString &section)
 	return QStringLiteral("%1\n'%2").arg(firstMonth,firstTime.toString("yy"));
 }
 
+DiveListModel *DiveListModel::m_instance = NULL;
+
 DiveListModel::DiveListModel(QObject *parent) : QAbstractListModel(parent)
 {
+	m_instance = this;
 }
 
 void DiveListModel::insertDive(int i)
@@ -271,6 +274,11 @@ QString DiveListModel::startAddDive()
 	return QString::number(d->id);
 }
 
+DiveListModel *DiveListModel::instance()
+{
+	return m_instance;
+}
+
 struct dive *DiveListModel::getDive(int i)
 {
 	if (i < 0 || i >= dive_table.nr) {

qt-models/divelistmodel.h

@@ -6,7 +6,6 @@
 #include <QSortFilterProxyModel>
 
 #include "core/subsurface-qt/DiveObjectHelper.h"
-#include "core/singleton.h"
 
 class DiveListSortModel : public QSortFilterProxyModel
 {
@@ -29,7 +28,7 @@ private:
 	void updateFilterState();
 };
 
-class DiveListModel : public QAbstractListModel, public SillySingleton<DiveListModel>
+class DiveListModel : public QAbstractListModel
 {
 	Q_OBJECT
 public:
@@ -46,6 +45,7 @@ public:
 		DepthDurationRole,
 	};
 
+	static DiveListModel *instance();
 	DiveListModel(QObject *parent = 0);
 	void addDive(const QList<dive *> &listOfDives);
 	void addAllDives();
@@ -63,6 +63,8 @@ public:
 	QString startAddDive();
 	void resetInternalData();
 	Q_INVOKABLE DiveObjectHelper at(int i);
+private:
+	static DiveListModel *m_instance;
 };
 
 #endif // DIVELISTMODEL_H

qt-models/gpslistmodel.cpp

@@ -3,12 +3,16 @@
 #include "core/qthelper.h"
 #include <QVector>
 
+GpsListModel *GpsListModel::m_instance = NULL;
+
 GpsListModel::GpsListModel(QObject *parent) : QAbstractListModel(parent)
 {
+	m_instance = this;
 }
 
-void GpsListModel::update(QVector<gpsTracker> trackers)
+void GpsListModel::update()
 {
+	QVector<gpsTracker> trackers = QVector<gpsTracker>::fromList(GpsLocation::instance()->currentGPSInfo().values());
 	beginResetModel();
 	m_gpsFixes = trackers;
 	endResetModel();
@@ -58,3 +62,9 @@ QHash<int, QByteArray> GpsListModel::roleNames() const
 	roles[GpsLongitudeRole] = "longitude";
 	return roles;
 }
+
+GpsListModel *GpsListModel::instance()
+{
+	return m_instance;
+}
+

qt-models/gpslistmodel.h

@@ -3,10 +3,10 @@
 #define GPSLISTMODEL_H
 
 #include "core/gpslocation.h"
-#include "core/singleton.h"
+#include <QObject>
 #include <QAbstractListModel>
 
-class GpsListModel : public QAbstractListModel, public SillySingleton<GpsListModel>
+class GpsListModel : public QAbstractListModel
 {
 	Q_OBJECT
 public:
@@ -19,14 +19,16 @@ public:
 		GpsWhenRole
 	};
 
+	static GpsListModel *instance();
 	GpsListModel(QObject *parent = 0);
 	void clear();
 	int rowCount(const QModelIndex &parent = QModelIndex()) const;
 	QHash<int, QByteArray> roleNames() const;
 	QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const;
-	void update(QVector<gpsTracker> trackers);
+	void update();
 private:
 	QVector<gpsTracker> m_gpsFixes;
+	static GpsListModel *m_instance;
 };
 
 #endif // GPSLISTMODEL_H