[gtk/wip/otte/listview: 4/159] builder: Add gtk_builder_set_current_object()

[Benjamin Otte <otte src gnome org>]

commit 2bcdfdb5bb43dffb5169846b2f0738d2c0855d3c
Author: Benjamin Otte <otte redhat com>
Date:   Thu Nov 28 04:01:19 2019 +0100

    builder: Add gtk_builder_set_current_object()
    
    Use it as the default object for expression binds and when connecting
    signals. It is intended to work kind of as the "this" object while
    parsing. In fact, the term "current object" was stolen from the Java
    docs and various C++ tutorials for the this pointer.
    
    Set the current object in gtk_widget_init_template() and
    GtkListItemBuilder.
    
    This more-or-less replaces the object passed to
    gtk_builder_connect_signals() in GTK3.

 docs/reference/gtk/gtk4-sections.txt |  2 +
 gtk/gtkbuilder.c                     | 87 ++++++++++++++++++++++++++++++++++++
 gtk/gtkbuilder.h                     |  5 +++
 gtk/gtkwidget.c                      | 22 +--------
 4 files changed, 96 insertions(+), 20 deletions(-)
---
diff --git a/docs/reference/gtk/gtk4-sections.txt b/docs/reference/gtk/gtk4-sections.txt
index cb7ed29ddd..efa6c32df7 100644
--- a/docs/reference/gtk/gtk4-sections.txt
+++ b/docs/reference/gtk/gtk4-sections.txt
@@ -541,6 +541,8 @@ gtk_builder_extend_with_template
 gtk_builder_get_object
 gtk_builder_get_objects
 gtk_builder_expose_object
+gtk_builder_set_current_object
+gtk_builder_get_current_object
 gtk_builder_set_translation_domain
 gtk_builder_get_translation_domain
 gtk_builder_get_type_from_name
diff --git a/gtk/gtkbuilder.c b/gtk/gtkbuilder.c
index cafbe4e5f6..0be335e63b 100644
--- a/gtk/gtkbuilder.c
+++ b/gtk/gtkbuilder.c
@@ -253,6 +253,7 @@ static void gtk_builder_get_property   (GObject         *object,
 
 enum {
   PROP_0,
+  PROP_CURRENT_OBJECT,
   PROP_TRANSLATION_DOMAIN,
   LAST_PROP
 };
@@ -281,6 +282,7 @@ typedef struct
   gchar *filename;
   gchar *resource_prefix;
   GType template_type;
+  GObject *current_object;
 
   GtkBuilderClosureFunc closure_func;
   gpointer closure_data;
@@ -289,11 +291,22 @@ typedef struct
 
 G_DEFINE_TYPE_WITH_PRIVATE (GtkBuilder, gtk_builder, G_TYPE_OBJECT)
 
+static void
+gtk_builder_dispose (GObject *object)
+{
+  GtkBuilderPrivate *priv = gtk_builder_get_instance_private (GTK_BUILDER (object));
+
+  g_clear_object (&priv->current_object);
+
+  G_OBJECT_CLASS (gtk_builder_parent_class)->dispose (object);
+}
+
 static void
 gtk_builder_class_init (GtkBuilderClass *klass)
 {
   GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
 
+  gobject_class->dispose = gtk_builder_dispose;
   gobject_class->finalize = gtk_builder_finalize;
   gobject_class->set_property = gtk_builder_set_property;
   gobject_class->get_property = gtk_builder_get_property;
@@ -313,6 +326,18 @@ gtk_builder_class_init (GtkBuilderClass *klass)
                            NULL,
                            GTK_PARAM_READWRITE);
 
+ /**
+  * GtkBuilder:current-object:
+  *
+  * The object the builder is evaluating for.
+  */
+  builder_props[PROP_CURRENT_OBJECT] =
+      g_param_spec_object ("current-object",
+                           P_("Current object"),
+                           P_("The object the builder is evaluating for"),
+                           G_TYPE_OBJECT,
+                           GTK_PARAM_READWRITE);
+
   g_object_class_install_properties (gobject_class, LAST_PROP, builder_props);
 }
 
@@ -364,9 +389,14 @@ gtk_builder_set_property (GObject      *object,
 
   switch (prop_id)
     {
+    case PROP_CURRENT_OBJECT:
+      gtk_builder_set_current_object (builder, g_value_get_object (value));
+      break;
+
     case PROP_TRANSLATION_DOMAIN:
       gtk_builder_set_translation_domain (builder, g_value_get_string (value));
       break;
+
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -384,9 +414,14 @@ gtk_builder_get_property (GObject    *object,
 
   switch (prop_id)
     {
+    case PROP_CURRENT_OBJECT:
+      g_value_set_object (value, priv->current_object);
+      break;
+
     case PROP_TRANSLATION_DOMAIN:
       g_value_set_string (value, priv->domain);
       break;
+
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
       break;
@@ -1677,6 +1712,54 @@ gtk_builder_expose_object (GtkBuilder    *builder,
                        g_object_ref (object));
 }
 
+/**
+ * gtk_builder_get_current_object:
+ * @self: a #GtkBuilder
+ *
+ * Gets the current object set via gtk_builder_set_current_object().
+ *
+ * Returns: (nullable) (transfer none): the current object
+ **/
+GObject *
+gtk_builder_get_current_object (GtkBuilder *self)
+{
+  GtkBuilderPrivate *priv = gtk_builder_get_instance_private (self);
+
+  g_return_val_if_fail (GTK_IS_BUILDER (self), NULL);
+
+  return priv->current_object;
+}
+
+/**
+ * gtk_builder_set_current_object:
+ * @self: a #GtkBuilder
+ * @current_object: (nullable) (transfer none): the new current object or
+ *     %NULL for none
+ *
+ * Sets the current object for the @self. The current object can be
+ * tought of as the `this` object that the builder is working for and
+ * will often be used as the default object when an object is optional.
+ *
+ * gtk_widget_init_template() for example will set the current object to
+ * the widget the template is inited for.  
+ * For functions like gtk_builder_new_from_resource(), the current object
+ * will be %NULL.
+ **/
+void
+gtk_builder_set_current_object (GtkBuilder *self,
+                                GObject    *current_object)
+{
+  GtkBuilderPrivate *priv = gtk_builder_get_instance_private (self);
+
+  g_return_if_fail (GTK_IS_BUILDER (self));
+  g_return_if_fail (current_object || G_IS_OBJECT (current_object));
+
+  if (!g_set_object (&priv->current_object, current_object))
+    return;
+
+  g_object_notify_by_pspec (G_OBJECT (self), builder_props[PROP_CURRENT_OBJECT]);
+}
+
 /**
  * GtkBuilderClosureFunc:
  * @builder: a #GtkBuilder
@@ -2701,8 +2784,12 @@ gtk_builder_create_closure_for_funcptr (GtkBuilder *builder,
                                         gboolean    swapped,
                                         GObject    *object)
 {
+  GtkBuilderPrivate *priv = gtk_builder_get_instance_private (builder);
   GClosure *closure;
 
+  if (object == NULL)
+    object = priv->current_object;
+
   if (object)
     {
       if (swapped)
diff --git a/gtk/gtkbuilder.h b/gtk/gtkbuilder.h
index 3bc752852b..4c7e6e934c 100644
--- a/gtk/gtkbuilder.h
+++ b/gtk/gtkbuilder.h
@@ -142,6 +142,11 @@ void         gtk_builder_expose_object           (GtkBuilder    *builder,
                                                   const gchar   *name,
                                                   GObject       *object);
 GDK_AVAILABLE_IN_ALL
+GObject *    gtk_builder_get_current_object      (GtkBuilder    *self);
+GDK_AVAILABLE_IN_ALL
+void         gtk_builder_set_current_object      (GtkBuilder    *self,
+                                                  GObject       *current_object);
+GDK_AVAILABLE_IN_ALL
 void         gtk_builder_set_translation_domain  (GtkBuilder           *builder,
                                                   const gchar          *domain);
 GDK_AVAILABLE_IN_ALL
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 1f86d04bb3..c2a4ef1cbf 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -12113,24 +12113,6 @@ setup_template_child (GtkWidgetTemplate   *template_data,
   return TRUE;
 }
 
-static GClosure *
-gtk_widget_template_closure_func (GtkBuilder  *builder,
-                                  const char  *function_name,
-                                  gboolean     swapped,
-                                  GObject     *object,
-                                  gpointer     user_data,
-                                  GError     **error)
-{
-  if (object == NULL)
-    object = user_data;
-
-  return gtk_builder_create_cclosure (builder,
-                                      function_name,
-                                      swapped,
-                                      object,
-                                      error);
-}
-
 /**
  * gtk_widget_init_template:
  * @widget: a #GtkWidget
@@ -12172,6 +12154,8 @@ gtk_widget_init_template (GtkWidget *widget)
 
   builder = gtk_builder_new ();
 
+  gtk_builder_set_current_object (builder, G_OBJECT (widget));
+
   /* Setup closure handling. All signal data from a template receive the 
    * template instance as user data automatically.
    *
@@ -12180,8 +12164,6 @@ gtk_widget_init_template (GtkWidget *widget)
    */
   if (template->closure_func)
     gtk_builder_set_closure_func (builder, template->closure_func, template->closure_data, NULL);
-  else
-    gtk_builder_set_closure_func (builder, gtk_widget_template_closure_func, widget, NULL);
 
   /* Add any callback symbols declared for this GType to the GtkBuilder namespace */
   for (l = template->callbacks; l; l = l->next)