[devhelp] Settings lib: rename "singleton" -> "default instance"

[Sébastien Wilmet <swilmet src gnome org>]

commit fad7d685f278670527b819edcdae9b7a4b585329
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Mon Apr 2 08:07:55 2018 +0200

    Settings lib: rename "singleton" -> "default instance"
    
    Another step towards being able to customize the GSettings paths in an
    app.

 devhelp/dh-book-manager.c |    6 +++---
 devhelp/dh-init.c         |    2 +-
 devhelp/dh-settings.c     |   25 ++++++++++++-------------
 devhelp/dh-settings.h     |    4 ++--
 src/dh-preferences.c      |    2 +-
 5 files changed, 19 insertions(+), 20 deletions(-)
---
diff --git a/devhelp/dh-book-manager.c b/devhelp/dh-book-manager.c
index 98d3f94..c326cbd 100644
--- a/devhelp/dh-book-manager.c
+++ b/devhelp/dh-book-manager.c
@@ -355,7 +355,7 @@ load_books_disabled (DhBookManager *book_manager)
 
         g_assert (priv->books_disabled == NULL);
 
-        settings = dh_settings_get_singleton ();
+        settings = dh_settings_get_default ();
         contents_settings = dh_settings_peek_contents_settings (settings);
         books_disabled_strv = g_settings_get_strv (contents_settings, "books-disabled");
 
@@ -392,7 +392,7 @@ store_books_disabled (DhBookManager *book_manager)
         variant = g_variant_builder_end (builder);
         g_variant_builder_unref (builder);
 
-        settings = dh_settings_get_singleton ();
+        settings = dh_settings_get_default ();
         contents_settings = dh_settings_peek_contents_settings (settings);
         g_settings_set_value (contents_settings, "books-disabled", variant);
 }
@@ -837,7 +837,7 @@ dh_book_manager_init (DhBookManager *book_manager)
 
         load_books_disabled (book_manager);
 
-        settings = dh_settings_get_singleton ();
+        settings = dh_settings_get_default ();
         contents_settings = dh_settings_peek_contents_settings (settings);
         g_settings_bind (contents_settings, "group-books-by-language",
                          book_manager, "group-by-language",
diff --git a/devhelp/dh-init.c b/devhelp/dh-init.c
index 30f45e4..bdc8b11 100644
--- a/devhelp/dh-init.c
+++ b/devhelp/dh-init.c
@@ -82,7 +82,7 @@ dh_finalize (void)
          */
         if (!done) {
                 _dh_book_manager_unref_singleton ();
-                _dh_settings_unref_singleton ();
+                _dh_settings_unref_default ();
                 done = TRUE;
         }
 }
diff --git a/devhelp/dh-settings.c b/devhelp/dh-settings.c
index a23ce4c..09dfb7c 100644
--- a/devhelp/dh-settings.c
+++ b/devhelp/dh-settings.c
@@ -28,8 +28,7 @@ struct _DhSettingsPrivate {
         GSettings *settings_contents;
 };
 
-/* DhSettings is a singleton. */
-static DhSettings *singleton = NULL;
+static DhSettings *default_instance = NULL;
 
 G_DEFINE_TYPE_WITH_PRIVATE (DhSettings, dh_settings, G_TYPE_OBJECT);
 
@@ -46,8 +45,8 @@ dh_settings_dispose (GObject *object)
 static void
 dh_settings_finalize (GObject *object)
 {
-        if (singleton == DH_SETTINGS (object))
-                singleton = NULL;
+        if (default_instance == DH_SETTINGS (object))
+                default_instance = NULL;
 
         G_OBJECT_CLASS (dh_settings_parent_class)->finalize (object);
 }
@@ -91,23 +90,23 @@ _dh_settings_new (const gchar *contents_path)
 }
 
 DhSettings *
-dh_settings_get_singleton (void)
+dh_settings_get_default (void)
 {
-        if (singleton == NULL) {
-                singleton = _dh_settings_new (/* Must be compatible with Devhelp app version 3.28: */
-                                              "/org/gnome/devhelp/state/main/contents/");
+        if (default_instance == NULL) {
+                default_instance = _dh_settings_new (/* Must be compatible with Devhelp app version 3.28: */
+                                                     "/org/gnome/devhelp/state/main/contents/");
         }
 
-        return singleton;
+        return default_instance;
 }
 
 void
-_dh_settings_unref_singleton (void)
+_dh_settings_unref_default (void)
 {
-        if (singleton != NULL)
-                g_object_unref (singleton);
+        if (default_instance != NULL)
+                g_object_unref (default_instance);
 
-        /* singleton is not set to NULL here, it is set to NULL in
+        /* default_instance is not set to NULL here, it is set to NULL in
          * dh_settings_finalize() (i.e. when we are sure that the ref count
          * reaches 0).
          */
diff --git a/devhelp/dh-settings.h b/devhelp/dh-settings.h
index 95645f2..009dd3d 100644
--- a/devhelp/dh-settings.h
+++ b/devhelp/dh-settings.h
@@ -51,10 +51,10 @@ struct _DhSettingsClass {
 
 GType           dh_settings_get_type                    (void) G_GNUC_CONST;
 
-DhSettings *    dh_settings_get_singleton               (void);
+DhSettings *    dh_settings_get_default                 (void);
 
 G_GNUC_INTERNAL
-void            _dh_settings_unref_singleton            (void);
+void            _dh_settings_unref_default              (void);
 
 GSettings *     dh_settings_peek_contents_settings      (DhSettings *self);
 
diff --git a/src/dh-preferences.c b/src/dh-preferences.c
index bbeadf6..2d1b59f 100644
--- a/src/dh-preferences.c
+++ b/src/dh-preferences.c
@@ -622,7 +622,7 @@ dh_preferences_init (DhPreferences *prefs)
         /* setup GSettings bindings */
         settings_app = dh_settings_app_get_singleton ();
         settings_fonts = dh_settings_app_peek_fonts_settings (settings_app);
-        settings_lib = dh_settings_get_singleton ();
+        settings_lib = dh_settings_get_default ();
         settings_contents = dh_settings_peek_contents_settings (settings_lib);
         g_settings_bind (settings_fonts, "use-system-fonts",
                          priv->system_fonts_button, "active",