[Boost-bugs] [Boost C++ Libraries] #2584: boost::enable_shared_from_this + boost.python library

Subject: [Boost-bugs] [Boost C++ Libraries] #2584: boost::enable_shared_from_this + boost.python library
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-12-12 09:33:33

#2584: boost::enable_shared_from_this + boost.python library
--------------------------------------------------+-------------------------
 Reporter:  Nicolas Lelong <nico_ml_at_[hidden]>  |       Owner:  pdimov   
     Type:  Bugs                                  |      Status:  new      
Milestone:  Boost 1.38.0                          |   Component:  smart_ptr
  Version:  Boost 1.37.0                          |    Severity:  Problem  
 Keywords:  enable_shared_from_this               |  
--------------------------------------------------+-------------------------
 A problem that was raised, on february, on c++-sig mailing list about a
 problem happening when wrapping classes derived from
 'enable_shared_from_this' using boost.python library.

 The problem is briefly described in this post - including a patch to
 boost/shared_ptr.hpp that would allow to work around the problem.
 http://mail.python.org/pipermail/cplusplus-sig/2008-February/012973.html


 To make it short, boost.python creates shared_ptr objects, holding the
 wrapped c++ objects, with a custom deleter managing the python object
 reference count. This leads to something like that :

 #include <boost/enable_shared_from_this.hpp>

 namespace {[[BR]]
   class A : public boost::enable_shared_from_this<A>[[BR]]
   {[[BR]]
   public:[[BR]]
     ~A() {};[[BR]]
   };[[BR]]
   void my_deleter(void*)[[BR]]
   {[[BR]]
   }[[BR]]
 };[[BR]]
 BOOST_AUTO_TEST_CASE( test_enable_shared_from_this )[[BR]]
 {[[BR]]
   boost::shared_ptr<A> a( new A );[[BR]]
   {[[BR]]
     boost::shared_ptr<A> ater = [[BR]]
       boost::shared_ptr<A>( a.get(), my_deleter );[[BR]]
     // OP patch proposal:[[BR]]
     // boost::shared_ptr<A> ater = [[BR]]
     //   boost::shared_ptr<A>( a.get(), my_deleter[[BR]]
     //   , boost::dont_enable_shared_from_this() );[[BR]]
     BOOST_CHECK( a == ater );[[BR]]
   }[[BR]]
   boost::shared_ptr<A> abug = a->shared_from_this(); // this throws
 bad_weak_ptr[[BR]]
 }

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/2584>
Boost C++ Libraries <http://www.boost.org/>
Boost provides free peer-reviewed portable C++ source libraries.