Add --mutter-plugins command line argument

src/core/main.c: Add --mutter-plugins argument (overrides GConf value)
src/core/prefs.c src/include/prefs.h: Add meta_prefs_override_clutter_plugins()
   to set a value for clutter_plugins that overrides the value from GConf

src/core/main.c

@@ -220,6 +220,7 @@ typedef struct
   gchar *save_file;
   gchar *display_name;
   gchar *client_id;
+  gchar *mutter_plugins;
   gboolean replace_wm;
   gboolean disable_sm;
   gboolean print_version;
@@ -251,7 +252,7 @@ static GOptionContext *
 meta_parse_options (int *argc, char ***argv,
                     MetaArguments *meta_args)
 {
-  MetaArguments my_args = {NULL, NULL, NULL,
+  MetaArguments my_args = {NULL, NULL, NULL, NULL,
                            FALSE, FALSE, FALSE, FALSE, FALSE};
   GOptionEntry options[] = {
     {
@@ -307,6 +308,14 @@ meta_parse_options (int *argc, char ***argv,
       N_("Turn compositing off"),
       NULL
     },
+#ifdef WITH_CLUTTER
+    {
+      "mutter-plugins", 0, 0, G_OPTION_ARG_STRING,
+      &my_args.mutter_plugins,
+      N_("Comma-separated list of compositor plugins"),
+      "PLUGINS"
+    },
+#endif
     {NULL}
   };
   GOptionContext *ctx;
@@ -547,6 +556,25 @@ main (int argc, char **argv)
   if (meta_args.composite || meta_args.no_composite)
     meta_prefs_set_compositing_manager (meta_args.composite);
 
+  if (meta_args.mutter_plugins)
+    {
+      char **plugins = g_strsplit (meta_args.mutter_plugins, ",", -1);
+      char **plugin;
+      GSList *plugins_list = NULL;
+
+      for (plugin = plugins; *plugin; plugin++)
+        {
+          g_strstrip (*plugin);
+          plugins_list = g_slist_prepend (plugins_list, *plugin);
+        }
+
+      plugins_list = g_slist_reverse (plugins_list);
+      meta_prefs_override_clutter_plugins (plugins_list);
+
+      g_slist_free(plugins_list);
+      g_strfreev (plugins);
+    }
+
   if (!meta_display_open ())
     meta_exit (META_EXIT_ERROR);
   

src/core/prefs.c

@@ -113,6 +113,7 @@ static char *workspace_names[MAX_REASONABLE_WORKSPACES] = { NULL, };
 
 #ifdef WITH_CLUTTER
 static gboolean clutter_disabled = FALSE;
+static gboolean clutter_plugins_overridden = FALSE;
 static GSList *clutter_plugins = NULL;
 #endif
 
@@ -1044,8 +1045,9 @@ meta_prefs_init (void)
   handle_preference_init_int ();
 
 #ifdef WITH_CLUTTER
-  clutter_plugins = gconf_client_get_list (default_client, KEY_CLUTTER_PLUGINS,
+  if (!clutter_plugins_overridden)
-                                           GCONF_VALUE_STRING, &err);
+    clutter_plugins = gconf_client_get_list (default_client, KEY_CLUTTER_PLUGINS,
+                                             GCONF_VALUE_STRING, &err);
 
   cleanup_error (&err);
 #endif
@@ -1233,7 +1235,7 @@ change_notify (GConfClient    *client,
         queue_changed (META_PREF_WORKSPACE_NAMES);
     }
 #ifdef WITH_CLUTTER
-  else if (g_str_equal (key, KEY_CLUTTER_PLUGINS))
+  else if (g_str_equal (key, KEY_CLUTTER_PLUGINS) && !clutter_plugins_overridden)
     {
       GError *err = NULL;
       GSList *l;
@@ -2971,6 +2973,21 @@ meta_prefs_set_clutter_plugins (GSList *list)
       g_error_free (err);
     }
 }
+
+void
+meta_prefs_override_clutter_plugins (GSList *list)
+{
+  GError *err = NULL;
+  GSList *l;
+
+  clutter_plugins_overridden = TRUE;
+  clutter_plugins = NULL;
+
+  for (l = list; l; l = l->next)
+    clutter_plugins = g_slist_prepend (clutter_plugins, g_strdup(l->data));
+
+  clutter_plugins = g_slist_reverse (clutter_plugins);
+}
 #endif
 
 gboolean

src/include/prefs.h

@@ -133,11 +133,20 @@ void     meta_prefs_set_clutter_disabled (gboolean whether);
 GSList * meta_prefs_get_clutter_plugins (void);
 
 /**
- * Sets whether the compositor is turned on.
+ * Sets the list of plugins persistently in GConf
  *
- * \param whether   TRUE to turn on, FALSE to turn off
+ * \param list   list of plugin:option pairs
  */
 void meta_prefs_set_clutter_plugins (GSList *list);
+
+/**
+ * Sets the list of plugins temporarily for this process. The value
+ * from GConf will be ignored.
+ *
+ * \param list   list of plugin:option pairs
+ */
+void meta_prefs_override_clutter_plugins (GSList *list);
+
 #endif
 
 gboolean meta_prefs_get_live_hidden_windows (void);