[california/wip/730603-gsettings] Clean up some binding issues

[Jim Nelson <jnelson src gnome org>]

commit d811787591fc08f9e1706574db02178b3a6f46dd
Author: Jim Nelson <jim yorba org>
Date:   Thu May 29 17:31:43 2014 -0700

    Clean up some binding issues

 src/base/base-object.vala      |   17 +++++++++++++++++
 src/host/host-main-window.vala |   22 ++++++++++++++++++++--
 2 files changed, 37 insertions(+), 2 deletions(-)
---
diff --git a/src/base/base-object.vala b/src/base/base-object.vala
index 99025b4..97779dd 100644
--- a/src/base/base-object.vala
+++ b/src/base/base-object.vala
@@ -4,6 +4,10 @@
  * (version 2.1 or later).  See the COPYING file in this distribution.
  */
 
+// It's either this or double-unref Binding objects; see
+// https://bugzilla.gnome.org/show_bug.cgi?id=730967
+extern void g_binding_unbind(Binding *binding);
+
 namespace California {
 
 /**
@@ -15,6 +19,19 @@ public abstract class BaseObject : Object {
     }
     
     /**
+     * Helper for unbinding properties until g_binding_unbind() is bound.
+     *
+     * See [[https://bugzilla.gnome.org/show_bug.cgi?id=730967]]
+     */
+    public static void unbind_property(ref Binding? binding) {
+        if (binding == null)
+            return;
+        
+        g_binding_unbind(binding);
+        binding = null;
+    }
+    
+    /**
      * Returns a string representation of the object ''for debugging and logging only''.
      *
      * String conversion for other purposes (user labels, serialization, etc.) should be handled
diff --git a/src/host/host-main-window.vala b/src/host/host-main-window.vala
index a8d8657..ddb084a 100644
--- a/src/host/host-main-window.vala
+++ b/src/host/host-main-window.vala
@@ -51,6 +51,8 @@ public class MainWindow : Gtk.ApplicationWindow {
     private Gtk.Stack view_stack = new Gtk.Stack();
     private Gtk.HeaderBar headerbar = new Gtk.HeaderBar();
     private Gtk.Button today = new Gtk.Button.with_label(_("_Today"));
+    private Binding view_stack_binding;
+    private Gee.HashSet<string> view_stack_ids = new Gee.HashSet<string>();
     
     public MainWindow(Application app) {
         Object (application: app);
@@ -164,8 +166,23 @@ public class MainWindow : Gtk.ApplicationWindow {
         
         // bind stack's visible child property to the settings for it, both ways ... because we want
         // to initialize with the settings, use it as the source w/ SYNC_CREATE
-        Settings.instance.bind_property(Settings.PROP_CALENDAR_VIEW, view_stack, "visible-child-name",
-            BindingFlags.SYNC_CREATE | BindingFlags.BIDIRECTIONAL);
+        view_stack_binding = Settings.instance.bind_property(Settings.PROP_CALENDAR_VIEW, view_stack,
+            "visible-child-name", BindingFlags.SYNC_CREATE | BindingFlags.BIDIRECTIONAL,
+            transform_setting_to_calendar_view);
+        
+        // to prevent storing the different children's names as the widget is destroyed (cleared,
+        // i.e. remove each one by one), unbind before that occurs
+        view_stack.destroy.connect(() => { BaseObject.unbind_property(ref view_stack_binding); });
+    }
+    
+    // only allow known stack children ids through
+    private bool transform_setting_to_calendar_view(Binding binding, Value source, ref Value target) {
+        if (!view_stack_ids.contains(source.get_string()))
+            return false;
+        
+        target = source;
+        
+        return true;
     }
     
     public override void map() {
@@ -177,6 +194,7 @@ public class MainWindow : Gtk.ApplicationWindow {
     }
     
     private void add_controller(View.Controllable controller) {
+        view_stack_ids.add(controller.id);
         view_stack.add_titled(controller.get_container(), controller.id, controller.title);
         controller.get_container().show_all();
     }