ceph/src/boost/libs/signals2/example/predestructor_example.cpp

   1 // Minimal example of defining a predestructor for a class which
   2 // uses boost::signals2::deconstruct as its factory function.
   3 //
   4 // Copyright Frank Mori Hess 2009.
   5
   6 // Use, modification and
   7 // distribution is subject to the Boost Software License, Version
   8 // 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   9 // http://www.boost.org/LICENSE_1_0.txt)
  10 // For more information, see http://www.boost.org
  11
  12 #include <boost/shared_ptr.hpp>
  13 #include <boost/signals2/deconstruct.hpp>
  14 #include <iostream>
  15
  16 namespace bs2 = boost::signals2;
  17
  18 namespace mynamespace
  19 {
  20   class X
  21   {
  22   public:
  23     ~X()
  24     {
  25       std::cout << "cruel world!" << std::endl;
  26     }
  27     /* This adl_predestruct friend function will be found by
  28     via argument-dependent lookup when using boost::signals2::deconstruct. */
  29     friend void adl_predestruct(X *)
  30     {
  31       std::cout << "Goodbye, ";
  32     }
  33     /* boost::signals2::deconstruct always requires an adl_postconstruct function
  34     which can be found via argument-dependent, so we define one which does nothing. */
  35     template<typename T> friend
  36       void adl_postconstruct(const boost::shared_ptr<T> &, X *)
  37     {}
  38   private:
  39     friend class bs2::deconstruct_access;  // give boost::signals2::deconstruct access to private constructor
  40     // private constructor forces use of boost::signals2::deconstruct to create objects.
  41     X()
  42     {}
  43   };
  44 }
  45
  46 int main()
  47 {
  48   {
  49     boost::shared_ptr<mynamespace::X> x = bs2::deconstruct<mynamespace::X>();
  50   }
  51   return 0;
  52 }