id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
2584	boost::enable_shared_from_this + boost.python library	Nicolas Lelong <nico_ml@…>	Peter Dimov	"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]]
}




"	Bugs	closed	Boost 1.39.0	smart_ptr	Boost 1.37.0	Problem	fixed	enable_shared_from_this