ACE/examples/Smart_Pointers/Widget_Impl.h

   1 // -*- C++ -*-
   2
   3 //=============================================================================
   4 /**
   5  *  @file    Widget_Impl.h
   6  *
   7  *  @author Christopher Kohlhoff <chris@kohlhoff.com>
   8  */
   9 //=============================================================================
  10
  11 #ifndef WIDGET_IMPL_H
  12 #define WIDGET_IMPL_H
  13
  14 #include "Widget.h"
  15 #include "Widget_Part.h"
  16
  17 #include "ace/Unbounded_Queue.h"
  18 #include "ace/Refcounted_Auto_Ptr.h"
  19 #include "ace/Synch_Traits.h"
  20 #include "ace/Thread_Mutex.h"
  21
  22 /**
  23  * @class Widget_Impl
  24  *
  25  * @brief An implementation of the Widget interface.
  26  */
  27 class Widget_Impl : public Widget
  28 {
  29 public:
  30   /// Constructor.
  31   Widget_Impl ();
  32
  33   /// Destructor.
  34   virtual ~Widget_Impl ();
  35
  36   /// Add a new part to the widget. The widget takes ownership of the part
  37   /// object.
  38   virtual void add_part (Widget_Part *part);
  39
  40   /// Remove a random part from the widget. Ownership of the part is returned
  41   /// to the caller.
  42   virtual Widget_Part *remove_part ();
  43
  44   /// Ask the widget to print information about the parts that it contains.
  45   virtual void list_parts ();
  46
  47 private:
  48   /// The parts which make up this widget. The set actually contains instances
  49   /// of ACE_Refcounted_Auto_Ptr to automatically manage the lifetimes of the
  50   /// constituent parts.
  51   ///
  52   /// Some things to note about the choice of ACE_Refcounted_Auto_Ptr:
  53   /// - We cannot use auto_ptr to manage the objects, since auto_ptr does not
  54   ///   support the copying and assignment semantics necessary for storage in
  55   ///   a container.
  56   /// - The ACE_Strong_Bound_Ptr reference counted pointer could be used to
  57   ///   store objects in a container, however (for reasons of safety) it
  58   ///   provides no way to release ownership of the object from the smart
  59   ///   pointer. We need to be able to release ownership to implement the
  60   ///   remove_part method.
  61   /// - ACE_Refcounted_Ptr can both be stored in containers and allows us to
  62   ///   release ownership of the pointer that it contains.
  63   ACE_Unbounded_Queue<ACE_Refcounted_Auto_Ptr<Widget_Part, ACE_SYNCH_MUTEX> > parts_;
  64 };
  65
  66 #endif /* WIDGET_IMPL_H */