View_Subscriber and View_Linked are two class templates derived from the Bakery::View template.
A View_Subscriber is linked with one or more View_Linked. (The implementation of the association is View_Subscriber <-> Bakery::View to reduce dependencies, but subscribees MUST be View_Linked based objects).

The View_Subscriber provides the following public methods :
- subscribe_view, unsubscribe_view, delete_subscribed_views are used to add / remove (one or all) subscribees
- notify_subscribees() notifies the subscribees about a change in the Subscriber view
- set_entity() sets the subscriber record

The View_Linked provides the following public methods :
- set_parent_entity() sets the subscriber entity. This method calls the load_from_document() method which should rely on the subscriber entity.
- parent_change_before_callback and parent_change_after_callback are two virtual method which are called respectively before and after the load_from_document() methods. You may overload them to extend the default behaviour without overload the set_parent_entity method.

Make your App use those templates

First of all, your app should use the Bakery framework ! You should read explanations here.

Navigator / Target

Create the Navigator view

    class ViewExampleNavigator :
      public BakeryExtras::View_Navigator < DocumentExample, KeyTypeExample >         
      {
        public:
        // standard overrides (Bakery::View)
        virtual void load_from_document();
        // declare and implement a method which
        // call Navigate() on response of a user event
      }; 

Create the Target view

    class ViewExampleTarget :
        public BakeryExtras::View_Target< DocumentExample, KeyTypeExample >
        {
        public:
            ViewExampleTarget(void);
            ~ViewExampleTarget(void);
            // overrides
            virtual void load_from_document();
            virtual void Goto(KeyTypeExample const &key);
        };

Make your app use the Navigator / Target views

The main view connected to your app should link together Navigator and Target views (for instance in the constructor) :
    class View : public MMI,
        public Bakery::View<DocumentExample>
       {
       public:
         View() :
        _view_target_example(0),
        _view_navigator_example(0)
        {
            _view_target_example = new ViewExampleTarget();
            _view_navigator_example = new ViewExampleNavigator();
            _view_navigator_example->setTarget(_view_target_example);
        };
         virtual ~View();
       private:
           ViewExampleTarget * _view_target_example;       
           ViewExampleNavigator * _view_navigator_example;
        };

Subscriber / Linked

Create the Subscriber view

    class ViewExampleSubscriber :
      public BakeryExtras::View_Subscriber < DocumentExample, EntityExample >         
      {
        public:
        // standard overrides (Bakery::View)
        virtual void load_from_document(); // the load_from_document must call the notify_subscribees() method
      };

Create the Linked view

    class ViewExampleLinked :
      public BakeryExtras::View_Linked < DocumentExample, EntityExample >         
      {
        public:
        // standard overrides (Bakery::View)
        virtual void load_from_document(); // the load_from_document must relies on the _parent_entity attribute to display its data
      };

Make your app use the Subscriber / Linked views

The main view connected to your app should link together Navigator and Target views (for instance in the constructor) :
    class View : public MMI,
        public Bakery::View<DocumentExample>
       {
       public:
         View() :
        _view_subscriber_example(0),
        _view_linked_example(0)
        {
            _view_subscriber_example = new ViewExampleSubscriber();
            _view_linked_example = new ViewExampleLinked();
            _view_subscriber_example->subscribe_view(_view_linked_example);
        };
         virtual ~View();
       private:
           ViewExampleSubscriber * _view_subscriber_example;       
           ViewExampleLinked * _view_linked_example;
        };