ACE/examples/Smart_Pointers/Gadget_Part_Impl.h

   1 /* -*- C++ -*- */
   2 //=============================================================================
   3 /**
   4  *  @file    Gadget_Part_Impl.h
   5  *
   6  *  @author Christopher Kohlhoff <chris@kohlhoff.com>
   7  */
   8 //=============================================================================
   9
  10 #ifndef GADGET_PART_IMPL_H
  11 #define GADGET_PART_IMPL_H
  12
  13 #include "Gadget_Part.h"
  14 #include "Gadget.h"
  15
  16 /**
  17  * @class Gadget_Part_Impl
  18  *
  19  * @brief An implementation of the Gadget_Part interface.
  20  */
  21 class Gadget_Part_Impl : public Gadget_Part
  22 {
  23 public:
  24   /// Constructor.
  25   Gadget_Part_Impl (Gadget_ptr owner, const char* name, int size);
  26
  27   /// Destructor.
  28   virtual ~Gadget_Part_Impl ();
  29
  30   /// Ask the part to print information about itself.
  31   virtual void print_info ();
  32
  33   /// Ask the part to remove itself from the gadget that contains it.
  34   virtual void remove_from_owner ();
  35
  36 private:
  37   /// The gadget that contains this part.
  38   ///
  39   /// Some things to note about the choice of ACE_Weak_Bound_Ptr (from the
  40   /// typedef for Gadget_ptr):
  41   /// - We cannot use an ACE_Strong_Bound_Ptr (Gadget_var) since that would
  42   ///   result in circular ownership.
  43   /// - If we use a raw pointer we have no circular ownership problems, but we
  44   ///   are unable to guarantee the lifetime of the owner object for the
  45   ///   duration of the remove_from_owner call. This may not be a problem in
  46   ///   this limited example, but in multithreaded programs remove_from_owner
  47   ///   may be called from a different thread to the thread which manages the
  48   ///   owner's lifetime.
  49   /// - ACE_Weak_Bound_Ptr (Gadget_ptr) has no ownership semantics, so we have
  50   ///   no circular ownership problems. Weak pointers can also be converted
  51   ///   back into strong ones, so it is possible to guarantee the lifetime of
  52   ///   the owner object for the duration of the remove_from_owner call.
  53   Gadget_ptr owner_;
  54
  55   /// The name of this part.
  56   char *name_;
  57
  58   /// The size of this part.
  59   int size_;
  60 };
  61
  62 #endif /* GADGET_PART_IMPL_H */