themePrivate instances are kept in statics

as a static pointer with refcount if "global" and internal refcounted hash if created with name

src/plasma/private/theme_p.cpp

@@ -24,6 +24,7 @@
 #include <QFile>
 #include <QFileInfo>
 
+#include <kdirwatch.h>
 #include <kglobalsettings.h>
 #include <kwindoweffects.h>
 
@@ -39,23 +40,49 @@ const char *ThemePrivate::systemColorsTheme = "internal-system-colors";
 EffectWatcher *ThemePrivate::s_blurEffectWatcher = 0;
 #endif
 
-ThemePrivate::ThemePrivate(Theme *theme)
-    : colorScheme(QPalette::Active, KColorScheme::Window, KSharedConfigPtr(0)),
-        buttonColorScheme(QPalette::Active, KColorScheme::Button, KSharedConfigPtr(0)),
-        viewColorScheme(QPalette::Active, KColorScheme::View, KSharedConfigPtr(0)),
-        defaultWallpaperTheme(DEFAULT_WALLPAPER_THEME),
-        defaultWallpaperSuffix(DEFAULT_WALLPAPER_SUFFIX),
-        defaultWallpaperWidth(DEFAULT_WALLPAPER_WIDTH),
-        defaultWallpaperHeight(DEFAULT_WALLPAPER_HEIGHT),
-        pixmapCache(0),
-        cacheSize(0),
-        cachesToDiscard(NoCache),
-        locolor(false),
-        compositingActive(KWindowSystem::self()->compositingActive()),
-        blurActive(false),
-        isDefault(false),
-        useGlobal(true),
-        hasWallpapers(false)
+ThemePrivate *ThemePrivate::globalTheme = 0;
+int ThemePrivate::globalThemeRefCount = 0;
+QHash<QString, ThemePrivate *> ThemePrivate::themes = QHash<QString, ThemePrivate*>();
+QHash<QString, int> ThemePrivate::themesRefCount = QHash<QString, int>();
+
+
+class ThemePrivateSingleton
+{
+public:
+    ThemePrivateSingleton()
+    {
+        self.isDefault = true;
+
+        //FIXME: if/when kconfig gets change notification, this will be unnecessary
+        KDirWatch::self()->addFile(QStandardPaths::writableLocation(QStandardPaths::ConfigLocation) + QLatin1Char('/') + ThemePrivate::themeRcFile);
+        QObject::connect(KDirWatch::self(), SIGNAL(created(QString)), &self, SLOT(settingsFileChanged(QString)));
+        QObject::connect(KDirWatch::self(), SIGNAL(dirty(QString)), &self, SLOT(settingsFileChanged(QString)));
+    }
+
+   ThemePrivate self;
+};
+
+Q_GLOBAL_STATIC(ThemePrivateSingleton, themePrivateSelf)
+
+
+ThemePrivate::ThemePrivate(QObject *parent)
+    : QObject(parent),
+      colorScheme(QPalette::Active, KColorScheme::Window, KSharedConfigPtr(0)),
+      buttonColorScheme(QPalette::Active, KColorScheme::Button, KSharedConfigPtr(0)),
+      viewColorScheme(QPalette::Active, KColorScheme::View, KSharedConfigPtr(0)),
+      defaultWallpaperTheme(DEFAULT_WALLPAPER_THEME),
+      defaultWallpaperSuffix(DEFAULT_WALLPAPER_SUFFIX),
+      defaultWallpaperWidth(DEFAULT_WALLPAPER_WIDTH),
+      defaultWallpaperHeight(DEFAULT_WALLPAPER_HEIGHT),
+      pixmapCache(0),
+      cacheSize(0),
+      cachesToDiscard(NoCache),
+      locolor(false),
+      compositingActive(KWindowSystem::self()->compositingActive()),
+      blurActive(false),
+      isDefault(false),
+      useGlobal(true),
+      hasWallpapers(false)
 {
     ThemeConfig config;
     cacheTheme = config.cacheTheme();
@@ -87,6 +114,11 @@ ThemePrivate::~ThemePrivate()
     delete pixmapCache;
 }
 
+ThemePrivate *ThemePrivate::self()
+{
+    return &themePrivateSelf()->self;
+}
+
 KConfigGroup &ThemePrivate::config()
     {
         if (!cfg.isValid()) {

src/plasma/private/theme_p.h

@@ -65,9 +65,11 @@ class ThemePrivate : public QObject
     Q_OBJECT
 
 public:
-    ThemePrivate(Theme *theme);
+    ThemePrivate(QObject *parent = 0);
     ~ThemePrivate();
 
+    static ThemePrivate *self();
+
     KConfigGroup &config();
 
     QString findInTheme(const QString &image, const QString &theme, bool cache = true);
@@ -100,7 +102,10 @@ public:
 #if HAVE_X11
     static EffectWatcher *s_blurEffectWatcher;
 #endif
-    static QHash<QString, ThemePrivate *>dAssociations;
+    static ThemePrivate *globalTheme;
+    static int globalThemeRefCount;
+    static QHash<QString, ThemePrivate *> themes;
+    static QHash<QString, int> themesRefCount;
 
     QString themeName;
     KPluginInfo pluginInfo;

src/plasma/theme.cpp

@@ -74,8 +74,15 @@ Theme *Theme::defaultTheme()
 
 Theme::Theme(QObject *parent)
     : QObject(parent),
-      d(new ThemePrivate(this))
+      d(ThemePrivate::self())
 {
+    if (!ThemePrivate::globalTheme) {
+        ThemePrivate::globalTheme = new ThemePrivate;
+        ++ThemePrivate::globalThemeRefCount;
+    }
+
+    d = ThemePrivate::globalTheme;
+
     d->settingsChanged();
     if (QCoreApplication::instance()) {
         connect(QCoreApplication::instance(), SIGNAL(aboutToQuit()),
@@ -85,13 +92,20 @@ Theme::Theme(QObject *parent)
 }
 
 Theme::Theme(const QString &themeName, QObject *parent)
-    : QObject(parent),
-      d(new ThemePrivate(this))
+    : QObject(parent)
 {
+    if (!ThemePrivate::themes.contains(themeName)) {
+        ThemePrivate::themes[themeName] = new ThemePrivate;
+        ThemePrivate::themesRefCount[themeName] = 0;
+    }
+
+    ++ThemePrivate::themesRefCount[themeName];
+    d = ThemePrivate::themes[themeName];
+
     // turn off caching so we don't accidently trigger unnecessary disk activity at this point
     bool useCache = d->cacheTheme;
     d->cacheTheme = false;
-    setThemeName(themeName);
+    d->setThemeName(themeName, true);
     d->cacheTheme = useCache;
     if (QCoreApplication::instance()) {
         connect(QCoreApplication::instance(), SIGNAL(aboutToQuit()),
@@ -111,11 +125,48 @@ Theme::~Theme()
     }
 
     d->onAppExitCleanup();
+
+    if (d == ThemePrivate::globalTheme) {
+        --ThemePrivate::globalThemeRefCount;
+        if (ThemePrivate::globalThemeRefCount == 0) {
+            delete ThemePrivate::globalTheme;
+        }
+    } else {
+        --ThemePrivate::themesRefCount[d->themeName];
+        if (ThemePrivate::themesRefCount[d->themeName] == 0) {
+            ThemePrivate *themePrivate = ThemePrivate::themes[d->themeName];
+            ThemePrivate::themes.remove(d->themeName);
+            ThemePrivate::themesRefCount.remove(d->themeName);
+            delete themePrivate;
+        }
+    }
     delete d;
 }
 
 void Theme::setThemeName(const QString &themeName)
 {
+    if (d->themeName == themeName) {
+        return;
+    }
+
+    if (d != ThemePrivate::globalTheme) {
+        --ThemePrivate::themesRefCount[d->themeName];
+        if (ThemePrivate::themesRefCount[d->themeName] == 0) {
+            ThemePrivate *themePrivate = ThemePrivate::themes[d->themeName];
+            ThemePrivate::themes.remove(d->themeName);
+            ThemePrivate::themesRefCount.remove(d->themeName);
+            delete themePrivate;
+        }
+    }
+
+    if (!ThemePrivate::themes.contains(themeName)) {
+        ThemePrivate::themes[themeName] = new ThemePrivate;
+        ThemePrivate::themesRefCount[themeName] = 0;
+    }
+
+    ++ThemePrivate::themesRefCount[themeName];
+    d = ThemePrivate::themes[themeName];
+
     d->setThemeName(themeName, true);
 }