From c8e8ccfa22a888e4f7930f80814691c35e6c2408 Mon Sep 17 00:00:00 2001
From: Dave Abrahams <dave@boostpro.com>
Date: Mon, 26 Jul 2004 15:34:36 +0000
Subject: [PATCH] New-style polymorphism

[SVN r24083]
---
 build/Jamfile                                 |   1 +
 include/boost/python/base_type_traits.hpp     |   6 +
 include/boost/python/class.hpp                |  79 +++++----
 .../python/converter/return_from_python.hpp   |   2 +
 include/boost/python/detail/enable_if.hpp     |  70 ++++++++
 include/boost/python/detail/is_wrapper.hpp    |  29 ++++
 include/boost/python/detail/sfinae.hpp        |  13 ++
 include/boost/python/detail/unwind_type.hpp   | 150 -----------------
 .../boost/python/detail/unwrap_type_id.hpp    |  31 ++++
 .../boost/python/detail/unwrap_wrapper.hpp    |  48 ++++++
 include/boost/python/detail/wrapper_base.hpp  |  86 ++++++++++
 include/boost/python/extract.hpp              |  15 +-
 .../boost/python/object/class_metadata.hpp    |  76 ++++++---
 .../boost/python/object/pointer_holder.hpp    |  33 +++-
 include/boost/python/object/value_holder.hpp  |  22 ++-
 include/boost/python/override.hpp             | 132 +++++++++++++++
 include/boost/python/to_python_indirect.hpp   | 108 ++++++------
 include/boost/python/wrapper.hpp              |  30 ++++
 src/object/life_support.cpp                   |   2 +-
 src/wrapper.cpp                               |  65 +++++++
 test/Jamfile                                  |   1 +
 test/embedding.cpp                            |  22 +--
 test/polymorphism2.cpp                        | 159 ++++++++++++++++++
 test/polymorphism2.py                         |  71 ++++++++
 24 files changed, 957 insertions(+), 294 deletions(-)
 create mode 100755 include/boost/python/detail/enable_if.hpp
 create mode 100755 include/boost/python/detail/is_wrapper.hpp
 create mode 100755 include/boost/python/detail/sfinae.hpp
 delete mode 100644 include/boost/python/detail/unwind_type.hpp
 create mode 100755 include/boost/python/detail/unwrap_type_id.hpp
 create mode 100755 include/boost/python/detail/unwrap_wrapper.hpp
 create mode 100755 include/boost/python/detail/wrapper_base.hpp
 create mode 100755 include/boost/python/override.hpp
 create mode 100755 include/boost/python/wrapper.hpp
 create mode 100755 src/wrapper.cpp
 create mode 100755 test/polymorphism2.cpp
 create mode 100644 test/polymorphism2.py

diff --git a/build/Jamfile b/build/Jamfile
index 428f161c..59dd3912 100644
--- a/build/Jamfile
+++ b/build/Jamfile
@@ -53,6 +53,7 @@ if [ check-python-config ]
     object/iterator.cpp
     object_protocol.cpp
     object_operators.cpp
+    wrapper.cpp
     ;
   
   dll boost_python
diff --git a/include/boost/python/base_type_traits.hpp b/include/boost/python/base_type_traits.hpp
index 12322539..e1c6a484 100755
--- a/include/boost/python/base_type_traits.hpp
+++ b/include/boost/python/base_type_traits.hpp
@@ -32,6 +32,12 @@ struct base_type_traits<PyTypeObject>
     typedef PyObject type;
 };
 
+template <>
+struct base_type_traits<PyMethodObject>
+{
+    typedef PyObject type;
+};
+
 }} // namespace boost::python
 
 #endif // BASE_TYPE_TRAITS_DWA2002614_HPP
diff --git a/include/boost/python/class.hpp b/include/boost/python/class.hpp
index d5c0de6a..b98435be 100644
--- a/include/boost/python/class.hpp
+++ b/include/boost/python/class.hpp
@@ -29,6 +29,8 @@
 # include <boost/python/detail/operator_id.hpp>
 # include <boost/python/detail/def_helper.hpp>
 # include <boost/python/detail/force_instantiate.hpp>
+# include <boost/python/detail/unwrap_type_id.hpp>
+# include <boost/python/detail/unwrap_wrapper.hpp>
 
 # include <boost/type_traits/is_same.hpp>
 # include <boost/type_traits/is_member_function_pointer.hpp>
@@ -151,7 +153,7 @@ namespace detail
 // This is the primary mechanism through which users will expose
 // C++ classes to Python.
 template <
-    class T // class being wrapped
+    class W // class being wrapped
     , class X1 // = detail::not_specified
     , class X2 // = detail::not_specified
     , class X3 // = detail::not_specified
@@ -160,9 +162,9 @@ class class_ : public objects::class_base
 {
  public: // types
     typedef objects::class_base base;
-    typedef class_<T,X1,X2,X3> self;
-    typedef typename objects::class_metadata<T,X1,X2,X3> metadata;
-    typedef T wrapped_type;
+    typedef class_<W,X1,X2,X3> self;
+    typedef typename objects::class_metadata<W,X1,X2,X3> metadata;
+    typedef W wrapped_type;
     
  private: // types
 
@@ -175,7 +177,7 @@ class class_ : public objects::class_base
         id_vector()
         {
             // Stick the derived class id into the first element of the array
-            ids[0] = type_id<T>();
+            ids[0] = detail::unwrap_type_id((W*)0, (W*)0);
 
             // Write the rest of the elements into succeeding positions.
             type_info* p = ids + 1;
@@ -231,7 +233,9 @@ class class_ : public objects::class_base
     template <class F>
     self& def(char const* name, F f)
     {
-        this->def_impl(name, f, detail::def_helper<char const*>(0), &f);
+        this->def_impl(
+            detail::unwrap_wrapper((W*)0)
+          , name, f, detail::def_helper<char const*>(0), &f);
         return *this;
     }
 
@@ -250,9 +254,10 @@ class class_ : public objects::class_base
         //      def(name, function, doc_string, policy)
 
         this->def_impl(
-            name, fn
-            , detail::def_helper<A1,A2>(a1,a2)
-            , &fn);
+            detail::unwrap_wrapper((W*)0)
+          , name, fn
+          , detail::def_helper<A1,A2>(a1,a2)
+          , &fn);
 
         return *this;
     }
@@ -261,9 +266,10 @@ class class_ : public objects::class_base
     self& def(char const* name, Fn fn, A1 const& a1, A2 const& a2, A3 const& a3)
     {
         this->def_impl(
-            name, fn
-            , detail::def_helper<A1,A2,A3>(a1,a2,a3)
-            , &fn);
+            detail::unwrap_wrapper((W*)0)
+          , name, fn
+          , detail::def_helper<A1,A2,A3>(a1,a2,a3)
+          , &fn);
 
         return *this;
     }
@@ -371,7 +377,8 @@ class class_ : public objects::class_base
         typedef typename api::is_object_operators<F>::type is_obj_or_proxy;
         
         return this->make_fn_impl(
-            f, is_obj_or_proxy(), (char*)0, detail::is_data_member_pointer<F>()
+            detail::unwrap_wrapper((W*)0)
+          , f, is_obj_or_proxy(), (char*)0, detail::is_data_member_pointer<F>()
         );
     }
     
@@ -381,32 +388,33 @@ class class_ : public objects::class_base
         typedef typename api::is_object_operators<F>::type is_obj_or_proxy;
         
         return this->make_fn_impl(
-            f, is_obj_or_proxy(), (int*)0, detail::is_data_member_pointer<F>()
+            detail::unwrap_wrapper((W*)0)
+          , f, is_obj_or_proxy(), (int*)0, detail::is_data_member_pointer<F>()
         );
     }
     
-    template <class F>
-    object make_fn_impl(F const& f, mpl::false_, void*, mpl::false_)
+    template <class T, class F>
+    object make_fn_impl(T*, F const& f, mpl::false_, void*, mpl::false_)
     {
         return python::make_function(f, default_call_policies(), detail::get_signature(f, (T*)0));
     }
 
-    template <class D, class B>
-    object make_fn_impl(D B::*pm_, mpl::false_, char*, mpl::true_)
+    template <class T, class D, class B>
+    object make_fn_impl(T*, D B::*pm_, mpl::false_, char*, mpl::true_)
     {
         D T::*pm = pm_;
         return python::make_getter(pm);
     }
 
-    template <class D, class B>
-    object make_fn_impl(D B::*pm_, mpl::false_, int*, mpl::true_)
+    template <class T, class D, class B>
+    object make_fn_impl(T*, D B::*pm_, mpl::false_, int*, mpl::true_)
     {
         D T::*pm = pm_;
         return python::make_setter(pm);
     }
 
-    template <class F>
-    object make_fn_impl(F const& x, mpl::true_, void*, mpl::false_)
+    template <class T, class F>
+    object make_fn_impl(T*, F const& x, mpl::true_, void*, mpl::false_)
     {
         return x;
     }
@@ -462,9 +470,10 @@ class class_ : public objects::class_base
     // generic visitor and everything else.
     //
     // @group def_impl {
-    template <class Helper, class LeafVisitor, class Visitor>
+    template <class T, class Helper, class LeafVisitor, class Visitor>
     inline void def_impl(
-        char const* name
+        T*
+      , char const* name
       , LeafVisitor
       , Helper const& helper
       , def_visitor<Visitor> const* v
@@ -473,9 +482,10 @@ class class_ : public objects::class_base
         v->visit(*this, name,  helper);
     }
 
-    template <class Fn, class Helper>
+    template <class T, class Fn, class Helper>
     inline void def_impl(
-        char const* name
+        T*
+      , char const* name
       , Fn fn
       , Helper const& helper
       , ...
@@ -510,7 +520,7 @@ class class_ : public objects::class_base
         , Helper const& helper
         , mpl::bool_<true>)
     {
-        detail::error::virtual_function_default<T,Fn>::must_be_derived_class_member(
+        detail::error::virtual_function_default<W,Fn>::must_be_derived_class_member(
             helper.default_implementation());
             
         objects::add_to_namespace(
@@ -554,7 +564,8 @@ class class_ : public objects::class_base
         , ...)
     {
         this->def_impl(
-            name
+            detail::unwrap_wrapper((W*)0)
+          , name
           , fn
           , detail::def_helper<A1>(a1)
           , &fn
@@ -569,23 +580,23 @@ class class_ : public objects::class_base
 // implementations
 //
 
-template <class T, class X1, class X2, class X3>
-inline class_<T,X1,X2,X3>::class_(char const* name, char const* doc)
+template <class W, class X1, class X2, class X3>
+inline class_<W,X1,X2,X3>::class_(char const* name, char const* doc)
     : base(name, id_vector::size, id_vector().ids, doc)
 {
     this->initialize(init<>());
 //  select_holder::assert_default_constructible();
 }
 
-template <class T, class X1, class X2, class X3>
-inline class_<T,X1,X2,X3>::class_(char const* name, no_init_t)
+template <class W, class X1, class X2, class X3>
+inline class_<W,X1,X2,X3>::class_(char const* name, no_init_t)
     : base(name, id_vector::size, id_vector().ids)
 {
     this->initialize(no_init);
 }
 
-template <class T, class X1, class X2, class X3>
-inline class_<T,X1,X2,X3>::class_(char const* name, char const* doc, no_init_t)
+template <class W, class X1, class X2, class X3>
+inline class_<W,X1,X2,X3>::class_(char const* name, char const* doc, no_init_t)
     : base(name, id_vector::size, id_vector().ids, doc)
 {
     this->initialize(no_init);
diff --git a/include/boost/python/converter/return_from_python.hpp b/include/boost/python/converter/return_from_python.hpp
index 999e1151..5db97485 100755
--- a/include/boost/python/converter/return_from_python.hpp
+++ b/include/boost/python/converter/return_from_python.hpp
@@ -9,9 +9,11 @@
 # include <boost/python/converter/rvalue_from_python_data.hpp>
 # include <boost/python/converter/registered.hpp>
 # include <boost/python/converter/registered_pointee.hpp>
+# include <boost/python/converter/object_manager.hpp>
 # include <boost/python/detail/void_ptr.hpp>
 # include <boost/python/detail/void_return.hpp>
 # include <boost/python/errors.hpp>
+# include <boost/python/handle.hpp>
 # include <boost/type_traits/has_trivial_copy.hpp>
 # include <boost/mpl/and.hpp>
 # include <boost/mpl/bool.hpp>
diff --git a/include/boost/python/detail/enable_if.hpp b/include/boost/python/detail/enable_if.hpp
new file mode 100755
index 00000000..247b06f2
--- /dev/null
+++ b/include/boost/python/detail/enable_if.hpp
@@ -0,0 +1,70 @@
+// Copyright David Abrahams 2004. Distributed under the Boost
+// Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#ifndef ENABLE_IF_DWA2004722_HPP
+# define ENABLE_IF_DWA2004722_HPP
+
+# include <boost/python/detail/sfinae.hpp>
+# include <boost/detail/workaround.hpp>
+
+# if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
+#  include <boost/mpl/if.hpp>
+
+namespace boost { namespace python { namespace detail { 
+
+template <class C, class T = int>
+struct enable_if_arg
+{
+    typedef typename mpl::if_<C,T,int&>::type type;
+};
+             
+template <class C, class T = int>
+struct disable_if_arg
+{
+    typedef typename mpl::if_<C,int&,T>::type type;
+};
+             
+template <class C, class T>
+struct enable_if_ret
+{
+    typedef typename mpl::if_<C,T,int[2]>::type type;
+};
+             
+template <class C, class T>
+struct disable_if_ret
+{
+    typedef typename mpl::if_<C,int[2],T>::type type;
+};
+             
+}}} // namespace boost::python::detail
+
+# elif !defined(BOOST_NO_SFINAE)
+#  include <boost/utility/enable_if.hpp>
+
+namespace boost { namespace python { namespace detail { 
+
+template <class C, class T>
+struct enable_if_arg
+  : enable_if<C,T>
+{};
+             
+template <class C, class T>
+struct disable_if_arg
+  : disable_if<C,T>
+{};
+             
+template <class C, class T>
+struct enable_if_ret
+  : enable_if<C,T>
+{};
+             
+template <class C, class T>
+struct disable_if_ret
+  : disable_if<C,T>
+{};
+             
+}}} // namespace boost::python::detail
+
+# endif
+
+#endif // ENABLE_IF_DWA2004722_HPP
diff --git a/include/boost/python/detail/is_wrapper.hpp b/include/boost/python/detail/is_wrapper.hpp
new file mode 100755
index 00000000..d7bce7b6
--- /dev/null
+++ b/include/boost/python/detail/is_wrapper.hpp
@@ -0,0 +1,29 @@
+// Copyright David Abrahams 2004. Distributed under the Boost
+// Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#ifndef IS_WRAPPER_DWA2004723_HPP
+# define IS_WRAPPER_DWA2004723_HPP
+
+# include <boost/python/detail/prefix.hpp>
+# include <boost/mpl/bool.hpp>
+
+namespace boost { namespace python {
+
+template <class T> class wrapper;
+
+namespace detail
+{
+  typedef char (&is_not_wrapper)[2];
+  is_not_wrapper is_wrapper_helper(...);
+  template <class T>
+  char is_wrapper_helper(wrapper<T> const volatile*);
+
+  // A metafunction returning true iff T is [derived from] wrapper<U> 
+  template <class T>
+  struct is_wrapper
+    : mpl::bool_<(sizeof(detail::is_wrapper_helper((T*)0)) == 1)>
+  {};
+
+}}} // namespace boost::python::detail
+
+#endif // IS_WRAPPER_DWA2004723_HPP
diff --git a/include/boost/python/detail/sfinae.hpp b/include/boost/python/detail/sfinae.hpp
new file mode 100755
index 00000000..62818751
--- /dev/null
+++ b/include/boost/python/detail/sfinae.hpp
@@ -0,0 +1,13 @@
+// Copyright David Abrahams 2004. Distributed under the Boost
+// Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#ifndef SFINAE_DWA2004723_HPP
+# define SFINAE_DWA2004723_HPP
+
+# include <boost/python/detail/prefix.hpp>
+
+# if defined(BOOST_NO_SFINAE) && !defined(BOOST_MSVC)
+#  define BOOST_PYTHON_NO_SFINAE
+# endif
+
+#endif // SFINAE_DWA2004723_HPP
diff --git a/include/boost/python/detail/unwind_type.hpp b/include/boost/python/detail/unwind_type.hpp
deleted file mode 100644
index 5d6a9b84..00000000
--- a/include/boost/python/detail/unwind_type.hpp
+++ /dev/null
@@ -1,150 +0,0 @@
-// Copyright David Abrahams 2002.
-// Distributed under the Boost Software License, Version 1.0. (See
-// accompanying file LICENSE_1_0.txt or copy at
-// http://www.boost.org/LICENSE_1_0.txt)
-#ifndef UNWIND_TYPE_DWA200222_HPP
-# define UNWIND_TYPE_DWA200222_HPP
-
-# include <boost/python/detail/cv_category.hpp>
-# include <boost/python/detail/indirect_traits.hpp>
-# include <boost/type_traits/object_traits.hpp>
-
-namespace boost { namespace python { namespace detail { 
-
-template <class Generator, class U>
-inline typename Generator::result_type
-unwind_type_cv(U* p, cv_unqualified, Generator* = 0)
-{
-    return Generator::execute(p);
-}
-    
-template <class Generator, class U>
-inline typename Generator::result_type
-unwind_type_cv(U const* p, const_, Generator* = 0)
-{
-    return unwind_type(const_cast<U*>(p), (Generator*)0);
-}
-    
-template <class Generator, class U>
-inline typename Generator::result_type
-unwind_type_cv(U volatile* p, volatile_, Generator* = 0)
-{
-    return unwind_type(const_cast<U*>(p), (Generator*)0);
-}
-    
-template <class Generator, class U>
-inline typename Generator::result_type
-unwind_type_cv(U const volatile* p, const_volatile_, Generator* = 0)
-{
-    return unwind_type(const_cast<U*>(p), (Generator*)0);
-}
-    
-template <class Generator, class U>
-inline typename Generator::result_type
-unwind_ptr_type(U* p, Generator* = 0)
-{
-    typedef typename cv_category<U>::type tag;
-    return unwind_type_cv<Generator>(p, tag());
-}
-
-template <bool is_ptr>
-struct unwind_helper
-{
-    template <class Generator, class U>
-    static typename Generator::result_type
-    execute(U p, Generator* = 0)
-    {
-        return unwind_ptr_type(p, (Generator*)0);
-    }
-};
-
-template <>
-struct unwind_helper<false>
-{
-    template <class Generator, class U>
-    static typename Generator::result_type
-    execute(U& p, Generator* = 0)
-    {
-        return unwind_ptr_type(&p, (Generator*)0);
-    }
-};
-
-template <class Generator, class U>
-inline typename Generator::result_type
-unwind_type(U const& p, Generator* = 0)
-{
-    return unwind_helper<is_pointer<U>::value>::execute(p, (Generator*)0);
-}
-
-enum { direct_ = 0, pointer_ = 1, reference_ = 2, reference_to_pointer_ = 3 };
-template <int indirection> struct unwind_helper2;
-
-template <>
-struct unwind_helper2<direct_>
-{
-    template <class Generator, class U>
-    static typename Generator::result_type
-    execute(U(*)(), Generator* = 0)
-    {
-        return unwind_ptr_type((U*)0, (Generator*)0);
-    }
-};
-
-template <>
-struct unwind_helper2<pointer_>
-{
-    template <class Generator, class U>
-    static typename Generator::result_type
-    execute(U*(*)(), Generator* = 0)
-    {
-        return unwind_ptr_type((U*)0, (Generator*)0);
-    }
-};
-
-template <>
-struct unwind_helper2<reference_>
-{
-    template <class Generator, class U>
-    static typename Generator::result_type
-    execute(U&(*)(), Generator* = 0)
-    {
-        return unwind_ptr_type((U*)0, (Generator*)0);
-    }
-};
-
-template <>
-struct unwind_helper2<reference_to_pointer_>
-{
-    template <class Generator, class U>
-    static typename Generator::result_type
-    execute(U&(*)(), Generator* = 0)
-    {
-        return unwind_ptr_type(U(0), (Generator*)0);
-    }
-};
-
-// Call this one with both template parameters explicitly specified
-// and no function arguments:
-//
-//      return unwind_type<my_generator,T>();
-//
-// Doesn't work if T is an array type; we could handle that case, but
-// why bother?
-template <class Generator, class U>
-inline typename Generator::result_type
-unwind_type(boost::type<U>*p = 0, Generator* = 0)
-{
-    BOOST_STATIC_CONSTANT(int, indirection
-                          = (is_pointer<U>::value ? pointer_ : 0)
-                          + (is_reference_to_pointer<U>::value
-                             ? reference_to_pointer_
-                             : is_reference<U>::value
-                             ? reference_
-                             : 0));
-        
-    return unwind_helper2<indirection>::execute((U(*)())0,(Generator*)0);
-}
-
-}}} // namespace boost::python::detail
-
-#endif // UNWIND_TYPE_DWA200222_HPP
diff --git a/include/boost/python/detail/unwrap_type_id.hpp b/include/boost/python/detail/unwrap_type_id.hpp
new file mode 100755
index 00000000..96c1f530
--- /dev/null
+++ b/include/boost/python/detail/unwrap_type_id.hpp
@@ -0,0 +1,31 @@
+// Copyright David Abrahams 2004. Distributed under the Boost
+// Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#ifndef UNWRAP_TYPE_ID_DWA2004722_HPP
+# define UNWRAP_TYPE_ID_DWA2004722_HPP
+
+# include <boost/python/type_id.hpp>
+
+# include <boost/mpl/bool.hpp>
+
+namespace boost { namespace python {
+
+template <class T> class wrapper;
+
+namespace detail { 
+
+template <class T>
+inline type_info unwrap_type_id(T*, ...)
+{
+    return type_id<T>();
+}
+
+template <class U, class T>
+inline type_info unwrap_type_id(U*, wrapper<T>*)
+{
+    return type_id<T>();
+}
+
+}}} // namespace boost::python::detail
+
+#endif // UNWRAP_TYPE_ID_DWA2004722_HPP
diff --git a/include/boost/python/detail/unwrap_wrapper.hpp b/include/boost/python/detail/unwrap_wrapper.hpp
new file mode 100755
index 00000000..7ae5b233
--- /dev/null
+++ b/include/boost/python/detail/unwrap_wrapper.hpp
@@ -0,0 +1,48 @@
+// Copyright David Abrahams 2004. Distributed under the Boost
+// Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#ifndef UNWRAP_WRAPPER_DWA2004723_HPP
+# define UNWRAP_WRAPPER_DWA2004723_HPP
+
+# include <boost/python/detail/prefix.hpp>
+# include <boost/python/detail/is_wrapper.hpp>
+#  if defined(BOOST_PYTHON_NO_SFINAE)
+#   include <boost/mpl/apply_if.hpp>
+#   include <boost/mpl/identity.hpp>
+#  else 
+#   include <boost/python/detail/enable_if.hpp>
+#  endif 
+
+namespace boost { namespace python { namespace detail { 
+
+#  if defined(BOOST_PYTHON_NO_SFINAE)
+template <class T>
+struct unwrap_wrapper_helper
+{
+    typedef typename T::_wrapper_wrapped_type_ type;
+};
+  
+template <class T>
+typename mpl::apply_if<is_wrapper<T>,unwrap_wrapper_helper<T>,mpl::identity<T> >::type*
+unwrap_wrapper(T*)
+{
+    return 0;
+}
+#  else 
+template <class T>
+typename disable_if_ret<is_wrapper<T>,T*>::type
+unwrap_wrapper(T*)
+{
+    return 0;
+}
+
+template <class T>
+T* unwrap_wrapper(wrapper<T>*)
+{
+    return 0;
+}
+#  endif 
+
+}}} // namespace boost::python::detail
+
+#endif // UNWRAP_WRAPPER_DWA2004723_HPP
diff --git a/include/boost/python/detail/wrapper_base.hpp b/include/boost/python/detail/wrapper_base.hpp
new file mode 100755
index 00000000..99d23b29
--- /dev/null
+++ b/include/boost/python/detail/wrapper_base.hpp
@@ -0,0 +1,86 @@
+// Copyright David Abrahams 2004. Distributed under the Boost
+// Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#ifndef WRAPPER_BASE_DWA2004722_HPP
+# define WRAPPER_BASE_DWA2004722_HPP
+
+# include <boost/python/detail/prefix.hpp>
+# include <boost/type_traits/is_polymorphic.hpp>
+# include <boost/mpl/bool.hpp>
+
+namespace boost { namespace python {
+
+class override;
+
+namespace detail
+{
+  class BOOST_PYTHON_DECL wrapper_base;
+  
+  namespace wrapper_base_ // ADL disabler
+  {
+    inline PyObject* get_owner(wrapper_base const volatile& w);
+
+    inline PyObject*
+    owner_impl(void const volatile* x, mpl::false_)
+    {
+        return 0;
+    }
+    
+    template <class T>
+    inline PyObject*
+    owner_impl(T const volatile* x, mpl::true_)
+    {
+        if (wrapper_base const volatile* w = dynamic_cast<wrapper_base const volatile*>(x))
+        {
+            return wrapper_base_::get_owner(*w);
+        }
+        return 0;
+    }
+    
+    template <class T>
+    inline PyObject*
+    owner(T const volatile* x)
+    {
+        return wrapper_base_::owner_impl(x,is_polymorphic<T>());
+    }
+  }
+  
+  class BOOST_PYTHON_DECL wrapper_base
+  {
+      friend void initialize_wrapper(PyObject* self, wrapper_base* w);
+      friend PyObject* wrapper_base_::get_owner(wrapper_base const volatile& w);
+   protected:
+      wrapper_base() : m_self(0) {}
+          
+      override get_override(
+          char const* name, PyTypeObject* class_object) const;
+
+   private:
+      void detach();
+      
+   private:
+      PyObject* m_self;
+  };
+
+  namespace wrapper_base_ // ADL disabler
+  {
+    inline PyObject* get_owner(wrapper_base const volatile& w)
+    {
+        return w.m_self;
+    }
+  }
+  
+  inline void initialize_wrapper(PyObject* self, wrapper_base* w)
+  {
+      w->m_self = self;
+  }
+
+  inline void initialize_wrapper(PyObject* self, ...) {}
+
+  
+  
+} // namespace detail
+
+}} // namespace boost::python
+
+#endif // WRAPPER_BASE_DWA2004722_HPP
diff --git a/include/boost/python/extract.hpp b/include/boost/python/extract.hpp
index ecfb6ce0..f2269b1d 100644
--- a/include/boost/python/extract.hpp
+++ b/include/boost/python/extract.hpp
@@ -12,16 +12,23 @@
 # include <boost/python/converter/rvalue_from_python_data.hpp>
 # include <boost/python/converter/registered.hpp>
 # include <boost/python/converter/registered_pointee.hpp>
-# include <boost/call_traits.hpp>
+
 # include <boost/python/object_core.hpp>
 # include <boost/python/refcount.hpp>
-# include <boost/utility.hpp>
+
 # include <boost/python/detail/copy_ctor_mutates_rhs.hpp>
 # include <boost/python/detail/void_ptr.hpp>
 # include <boost/python/detail/void_return.hpp>
+# include <boost/utility.hpp>
+# include <boost/call_traits.hpp>
 
 namespace boost { namespace python {
 
+namespace api
+{
+  class object;
+}
+
 namespace converter
 {
   template <class Ptr>
@@ -125,7 +132,7 @@ struct extract
     }
     
     extract(PyObject*);
-    extract(object const&);
+    extract(api::object const&);
 };
 
 //
@@ -138,7 +145,7 @@ inline extract<T>::extract(PyObject* o)
 }
 
 template <class T>
-inline extract<T>::extract(object const& o)
+inline extract<T>::extract(api::object const& o)
     : base(o.ptr())
 {
 }
diff --git a/include/boost/python/object/class_metadata.hpp b/include/boost/python/object/class_metadata.hpp
index d9bda9b3..ef56d560 100755
--- a/include/boost/python/object/class_metadata.hpp
+++ b/include/boost/python/object/class_metadata.hpp
@@ -75,7 +75,7 @@ struct register_base_of
 // need some registration of their own.
 //
 template <class T, class Bases>
-void register_shared_ptr_from_python_and_casts(T*, Bases)
+inline void register_shared_ptr_from_python_and_casts(T*, Bases)
 {
     // Constructor performs registration
     python::detail::force_instantiate(converter::shared_ptr_from_python<T>());
@@ -166,16 +166,13 @@ struct class_metadata
         use_value_holder
       , mpl::identity<held_type>
       , pointee<held_type>
-    >::type wrapper;
+    >::type wrapped;
 
-    // Determine whether wrapper needs to be separately registered
-    typedef is_base_and_derived<T,wrapper> use_callback_class;
-
-    // Determine whether to use a holder with a back-reference
+    // Determine whether to use a "back-reference holder"
     typedef mpl::or_<
-        use_callback_class
-      , has_back_reference<T>
+        has_back_reference<T>
       , is_same<held_type_arg,T>
+      , is_base_and_derived<T,wrapped>
     > use_back_reference;
 
     // Select the holder.
@@ -183,7 +180,7 @@ struct class_metadata
         use_back_reference
       , mpl::if_<
             use_value_holder
-          , value_holder_back_reference<T, wrapper>
+          , value_holder_back_reference<T, wrapped>
           , pointer_holder_back_reference<held_type,T>
         >
       , mpl::if_<
@@ -195,52 +192,75 @@ struct class_metadata
     
     inline static void register_() // Register the runtime metadata.
     {
-        objects::register_shared_ptr_from_python_and_casts((T*)0, bases());
-
-        class_metadata::maybe_register_callback_class(use_callback_class());
-
-        class_metadata::maybe_register_class_to_python(is_noncopyable());
-        
-        class_metadata::maybe_register_pointer_to_python(
-            (use_value_holder*)0, (use_back_reference*)0);
+        class_metadata::register_aux((T*)0);
     }
 
  private:
+    template <class T2>
+    inline static void register_aux(python::wrapper<T2>*) 
+    {
+        class_metadata::register_aux2((T2*)0, mpl::true_());
+    }
+
+    inline static void register_aux(void*) 
+    {
+        typedef typename is_base_and_derived<T,wrapped>::type use_callback;
+        class_metadata::register_aux2((T*)0, use_callback());
+    }
+
+    template <class T2, class Callback>
+    inline static void register_aux2(T2*, Callback) 
+    {
+        objects::register_shared_ptr_from_python_and_casts((T2*)0, bases());
+        
+        class_metadata::maybe_register_callback_class((T2*)0, Callback());
+
+        class_metadata::maybe_register_class_to_python((T2*)0, is_noncopyable());
+        
+        class_metadata::maybe_register_pointer_to_python(
+            (T2*)0, (use_value_holder*)0, (use_back_reference*)0);
+    }
+
+
     //
     // Support for converting smart pointers to python
     //
-    inline static void maybe_register_pointer_to_python(void*,void*) {}
-    
-    inline static void maybe_register_pointer_to_python(mpl::false_*, mpl::false_*)
+    inline static void maybe_register_pointer_to_python(void*,void*,void*) {}
+
+    template <class T2>
+    inline static void maybe_register_pointer_to_python(T2*, mpl::false_*, mpl::false_*)
     {
         python::detail::force_instantiate(
             objects::class_value_wrapper<
                 held_type
-              , make_ptr_instance<T, pointer_holder<held_type, T> >
+              , make_ptr_instance<T2, pointer_holder<held_type, T2> >
             >()
         );
     }
     //
     // Support for registering to-python converters
     //
-    inline static void maybe_register_class_to_python(mpl::true_) {}
-    inline static void maybe_register_class_to_python(mpl::false_)
+    inline static void maybe_register_class_to_python(void*, mpl::true_) {}
+    
+    template <class T2>
+    inline static void maybe_register_class_to_python(T2*, mpl::false_)
     {
-        python::detail::force_instantiate(class_cref_wrapper<T, make_instance<T, holder> >());
+        python::detail::force_instantiate(class_cref_wrapper<T2, make_instance<T2, holder> >());
     }
 
     //
     // Support for registering callback classes
     //
-    inline static void maybe_register_callback_class(mpl::false_) {}
+    inline static void maybe_register_callback_class(void*, mpl::false_) {}
 
-    inline static void maybe_register_callback_class(mpl::true_)
+    template <class T2>
+    inline static void maybe_register_callback_class(T2*, mpl::true_)
     {
         objects::register_shared_ptr_from_python_and_casts(
-            (wrapper*)0, mpl::single_view<T>());
+            (wrapped*)0, mpl::single_view<T2>());
 
         // explicit qualification of type_id makes msvc6 happy
-        objects::copy_class_object(python::type_id<T>(), python::type_id<wrapper>());
+        objects::copy_class_object(python::type_id<T2>(), python::type_id<wrapped>());
     }
 };
 
diff --git a/include/boost/python/object/pointer_holder.hpp b/include/boost/python/object/pointer_holder.hpp
index 764848e8..d50c689d 100644
--- a/include/boost/python/object/pointer_holder.hpp
+++ b/include/boost/python/object/pointer_holder.hpp
@@ -12,13 +12,17 @@
 #  include <boost/type.hpp>
 
 #  include <boost/python/instance_holder.hpp>
-#  include <boost/python/type_id.hpp>
 #  include <boost/python/object/inheritance_query.hpp>
 #  include <boost/python/object/forward.hpp>
+
 #  include <boost/python/pointee.hpp>
+#  include <boost/python/type_id.hpp>
+
+#  include <boost/python/detail/wrapper_base.hpp>
 #  include <boost/python/detail/force_instantiate.hpp>
 #  include <boost/python/detail/preprocessor.hpp>
 
+
 #  include <boost/mpl/if.hpp>
 #  include <boost/mpl/apply.hpp>
 
@@ -31,6 +35,13 @@
 
 #  include <boost/detail/workaround.hpp>
 
+namespace boost { namespace python {
+
+template <class T> class wrapper;
+
+}}
+
+
 namespace boost { namespace python { namespace objects {
 
 #  if BOOST_WORKAROUND(__GNUC__, == 2)
@@ -55,6 +66,17 @@ struct pointer_holder : instance_holder
     
  private: // required holder implementation
     void* holds(type_info);
+    
+    template <class T>
+    inline void* holds_wrapped(type_info dst_t, wrapper<T>*,T* p)
+    {
+        return python::type_id<T>() == dst_t ? p : 0;
+    }
+    
+    inline void* holds_wrapped(type_info, ...)
+    {
+        return 0;
+    }
 
  private: // data members
     Pointer m_p;
@@ -107,6 +129,9 @@ void* pointer_holder<Pointer, Value>::holds(type_info dst_t)
     if (p == 0)
         return 0;
     
+    if (void* wrapped = holds_wrapped(dst_t, p, p))
+        return wrapped;
+    
     type_info src_t = python::type_id<Value>();
     return src_t == dst_t ? p : find_dynamic_type(p, src_t, dst_t);
 }
@@ -145,11 +170,13 @@ void* pointer_holder_back_reference<Pointer, Value>::holds(type_info dst_t)
 # if (N != 0)
     template< BOOST_PP_ENUM_PARAMS_Z(1, N, class A) >
 # endif
-    pointer_holder(PyObject* BOOST_PP_COMMA_IF(N) BOOST_PP_ENUM_BINARY_PARAMS_Z(1, N, A, a))
+    pointer_holder(PyObject* self BOOST_PP_COMMA_IF(N) BOOST_PP_ENUM_BINARY_PARAMS_Z(1, N, A, a))
         : m_p(new Value(
                 BOOST_PP_REPEAT_1ST(N, BOOST_PYTHON_UNFORWARD_LOCAL, nil)
             ))
-    {}
+    {
+        python::detail::initialize_wrapper(self, &*this->m_p);
+    }
 
 # undef N
 
diff --git a/include/boost/python/object/value_holder.hpp b/include/boost/python/object/value_holder.hpp
index f326821c..02687e33 100644
--- a/include/boost/python/object/value_holder.hpp
+++ b/include/boost/python/object/value_holder.hpp
@@ -13,6 +13,7 @@
 
 #  include <boost/python/instance_holder.hpp>
 #  include <boost/python/type_id.hpp>
+#  include <boost/python/wrapper.hpp>
 
 #  include <boost/python/object/inheritance_query.hpp>
 #  include <boost/python/object/forward.hpp>
@@ -49,7 +50,17 @@ struct value_holder : instance_holder
 
  private: // required holder implementation
     void* holds(type_info);
-
+    
+    template <class T>
+    inline void* holds_wrapped(type_info dst_t, wrapper<T>*,T* p)
+    {
+        return python::type_id<T>() == dst_t ? p : 0;
+    }
+    
+    inline void* holds_wrapped(type_info, ...)
+    {
+        return 0;
+    }
  private: // data members
     Value m_held;
 };
@@ -76,6 +87,9 @@ private: // required holder implementation
 template <class Value>
 void* value_holder<Value>::holds(type_info dst_t)
 {
+    if (void* wrapped = holds_wrapped(dst_t, &m_held, &m_held))
+        return wrapped;
+    
     type_info src_t = python::type_id<Value>();
     return src_t == dst_t ? &m_held
         : find_static_type(&m_held, src_t, dst_t);
@@ -114,11 +128,13 @@ void* value_holder_back_reference<Value,Held>::holds(
     template <BOOST_PP_ENUM_PARAMS_Z(1, N, class A)>
 # endif
     value_holder(
-      PyObject* BOOST_PP_COMMA_IF(N) BOOST_PP_ENUM_BINARY_PARAMS_Z(1, N, A, a))
+      PyObject* self BOOST_PP_COMMA_IF(N) BOOST_PP_ENUM_BINARY_PARAMS_Z(1, N, A, a))
         : m_held(
             BOOST_PP_REPEAT_1ST(N, BOOST_PYTHON_UNFORWARD_LOCAL, nil)
             )
-    {}
+    {
+        python::detail::initialize_wrapper(self, &this->m_held);
+    }
 
 # undef N
 
diff --git a/include/boost/python/override.hpp b/include/boost/python/override.hpp
new file mode 100755
index 00000000..dbc00303
--- /dev/null
+++ b/include/boost/python/override.hpp
@@ -0,0 +1,132 @@
+#if !defined(BOOST_PP_IS_ITERATING)
+
+// Copyright David Abrahams 2004. Distributed under the Boost
+// Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#ifndef OVERRIDE_DWA2004721_HPP
+# define OVERRIDE_DWA2004721_HPP
+
+# include <boost/python/detail/prefix.hpp>
+
+# include <boost/python/converter/return_from_python.hpp>
+
+# include <boost/python/extract.hpp>
+# include <boost/python/handle.hpp>
+
+#  include <boost/preprocessor/iterate.hpp>
+#  include <boost/preprocessor/repeat.hpp>
+#  include <boost/preprocessor/debug/line.hpp>
+#  include <boost/preprocessor/repetition/enum_params.hpp>
+#  include <boost/preprocessor/repetition/enum_binary_params.hpp>
+
+#  include <boost/type.hpp>
+
+namespace boost { namespace python {
+
+class override;
+
+namespace detail
+{
+  class wrapper_base;
+  
+  // The result of calling a method.
+  class method_result
+  {
+   private:
+      friend class override;
+      explicit method_result(PyObject* x)
+        : m_obj(x)
+      {}
+
+   public:
+      template <class T>
+      operator T()
+      {
+          converter::return_from_python<T> converter;
+          return converter(m_obj.release());
+      }
+
+#  if !defined(BOOST_MSVC) || BOOST_WORKAROUND(_MSC_FULL_VER, > 140040607)
+      template <class T>
+      operator T&() const
+      {
+          converter::return_from_python<T&> converter;
+          return converter(m_obj.release());
+      }
+#  endif 
+
+      template <class T>
+      T as(type<T>* = 0)
+      {
+          converter::return_from_python<T> converter;
+          return converter(m_obj.release());
+      }
+
+      template <class T>
+      T unchecked(type<T>* = 0)
+      {
+          return extract<T>(m_obj)();
+      }
+   private:
+      mutable handle<> m_obj;
+  };
+}
+
+class override : public object
+{
+ private:
+    friend class detail::wrapper_base;
+    override(handle<> x)
+      : object(x)
+    {}
+    
+ public:
+    detail::method_result
+    operator()() const
+    {
+        detail::method_result x(
+            PyEval_CallFunction(
+                this->ptr()
+              , const_cast<char*>("()")
+            ));
+        return x;
+    }
+
+# define BOOST_PYTHON_fast_arg_to_python_get(z, n, _)   \
+    , converter::arg_to_python<A##n>(a##n).get()
+
+# define BOOST_PP_ITERATION_PARAMS_1 (3, (1, BOOST_PYTHON_MAX_ARITY, <boost/python/override.hpp>))
+# include BOOST_PP_ITERATE()
+
+# undef BOOST_PYTHON_fast_arg_to_python_get
+};
+
+}} // namespace boost::python
+
+#endif // OVERRIDE_DWA2004721_HPP
+
+#else
+# if !(BOOST_WORKAROUND(__MWERKS__, > 0x3100)                      \
+        && BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3201)))
+#  line BOOST_PP_LINE(__LINE__, override.hpp)
+# endif 
+
+# define N BOOST_PP_ITERATION()
+
+template <
+    BOOST_PP_ENUM_PARAMS_Z(1, N, class A)
+    >
+detail::method_result
+operator()( BOOST_PP_ENUM_BINARY_PARAMS_Z(1, N, A, const& a) ) const
+{
+    detail::method_result x(
+        PyEval_CallFunction(
+            this->ptr()
+          , const_cast<char*>("(" BOOST_PP_REPEAT_1ST(N, BOOST_PYTHON_FIXED, "O") ")")
+            BOOST_PP_REPEAT_1ST(N, BOOST_PYTHON_fast_arg_to_python_get, nil)
+        ));
+    return x;
+}
+
+# undef N
+#endif 
diff --git a/include/boost/python/to_python_indirect.hpp b/include/boost/python/to_python_indirect.hpp
index cf457ec1..a39b723d 100644
--- a/include/boost/python/to_python_indirect.hpp
+++ b/include/boost/python/to_python_indirect.hpp
@@ -7,24 +7,58 @@
 
 # include <boost/python/detail/prefix.hpp>
 
-# include <boost/type_traits/object_traits.hpp>
 # include <boost/python/object/pointer_holder.hpp>
-# include <boost/python/object/instance.hpp>
-# include <boost/python/converter/registered.hpp>
-# include <boost/python/detail/unwind_type.hpp>
-# include <boost/python/detail/none.hpp>
-# include <boost/shared_ptr.hpp>
 # include <boost/python/object/make_ptr_instance.hpp>
-# include <memory>
+
+# include <boost/python/detail/none.hpp>
+
+# include <boost/python/refcount.hpp>
+
+# include <boost/type_traits/is_pointer.hpp>
+# include <boost/type_traits/is_polymorphic.hpp>
+
+# include <boost/mpl/bool.hpp>
+
+# if defined(__ICL) && __ICL < 600 
+#  include <boost/shared_ptr.hpp>
+# else 
+#  include <memory>
+# endif
 
 namespace boost { namespace python {
 
 template <class T, class MakeHolder>
 struct to_python_indirect
 {
-    PyObject* operator()(T ptr) const;
+    template <class U>
+    inline PyObject*
+    operator()(U const& ref) const
+    {
+        return this->execute(const_cast<U&>(ref), is_pointer<U>());
+    }
+
  private:
-    static PyTypeObject* type();
+    template <class U>
+    inline PyObject* execute(U* ptr, mpl::true_) const
+    {
+        // No special NULL treatment for references
+        if (ptr == 0)
+            return python::detail::none();
+        else
+            return this->execute(*ptr, mpl::false_());
+    }
+    
+    template <class U>
+    inline PyObject* execute(U const& x, mpl::false_) const
+    {
+        U* const p = &const_cast<U&>(x);
+        if (is_polymorphic<U>::value)
+        {
+            if (PyObject* o = detail::wrapper_base_::owner(p))
+                return incref(o);
+        }
+        return MakeHolder::execute(p);
+    }
 };
 
 //
@@ -34,9 +68,8 @@ namespace detail
 {
   struct make_owning_holder
   {
-      typedef PyObject* result_type;
       template <class T>
-      static result_type execute(T* p)
+      static PyObject* execute(T* p)
       {
           // can't use auto_ptr with Intel 5 and VC6 Dinkum library
           // for some reason. We get link errors against the auto_ptr
@@ -48,66 +81,21 @@ namespace detail
 # endif
           typedef objects::pointer_holder<smart_pointer, T> holder_t;
 
-          smart_pointer ptr(p);
+          smart_pointer ptr(const_cast<T*>(p));
           return objects::make_ptr_instance<T, holder_t>::execute(ptr);
       }
   };
 
   struct make_reference_holder
   {
-      typedef PyObject* result_type;
       template <class T>
-      static result_type execute(T* p)
+      static PyObject* execute(T* p)
       {
           typedef objects::pointer_holder<T*, T> holder_t;
-          return objects::make_ptr_instance<T, holder_t>::execute(p);
+          T* q = const_cast<T*>(p);
+          return objects::make_ptr_instance<T, holder_t>::execute(q);
       }
   };
-
-  struct get_pointer_class
-  {
-      typedef PyTypeObject* result_type;
-      template <class T>
-      static result_type execute(T* p)
-      {
-          BOOST_STATIC_ASSERT(is_class<T>::value);
-          return converter::registered<T>::converters.class_object;
-      }
-  };
-
-  // null_pointer_to_none -- return none() for null pointers and 0 for all other types/values
-  // 
-  // Uses simulated partial ordering
-  template <class T>
-  inline PyObject* null_pointer_to_none(T&, int)
-  {
-      return 0;
-  }
-
-  // overload for pointers
-  template <class T>
-  inline PyObject* null_pointer_to_none(T* x, long)
-  {
-      return x == 0 ? python::detail::none() : 0;
-  }
-}
-
-template <class T, class MakeHolder>
-inline PyObject* to_python_indirect<T,MakeHolder>::operator()(T x) const
-{
-    BOOST_STATIC_ASSERT(is_pointer<T>::value || is_reference<T>::value);
-        
-    PyObject* const null_result = detail::null_pointer_to_none(x, 1L);
-    if (null_result != 0)
-        return null_result;
-
-    return detail::unwind_type<MakeHolder>(x);
-}
-
-template <class T, class MakeHolder>
-inline PyTypeObject* to_python_indirect<T,MakeHolder>::type()
-{
-    return detail::unwind_type<detail::get_pointer_class,T>();
 }
 
 }} // namespace boost::python
diff --git a/include/boost/python/wrapper.hpp b/include/boost/python/wrapper.hpp
new file mode 100755
index 00000000..37d24e76
--- /dev/null
+++ b/include/boost/python/wrapper.hpp
@@ -0,0 +1,30 @@
+// Copyright David Abrahams 2004. Distributed under the Boost
+// Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#ifndef WRAPPER_DWA2004720_HPP
+# define WRAPPER_DWA2004720_HPP
+
+# include <boost/python/detail/wrapper_base.hpp>
+# include <boost/python/override.hpp>
+# include <boost/python/converter/registered.hpp>
+# include <boost/python/detail/sfinae.hpp>
+
+namespace boost { namespace python { 
+
+template <class T>
+class wrapper : public detail::wrapper_base
+{
+#   if defined(BOOST_PYTHON_NO_SFINAE)
+    typedef T _wrapper_wrapped_type_;
+#   endif 
+ protected:
+    override get_override(char const* name) const
+    {
+        return this->wrapper_base::get_override(
+            name, converter::registered<T>::converters.get_class_object());
+    }
+};
+
+}} // namespace boost::python
+
+#endif // WRAPPER_DWA2004720_HPP
diff --git a/src/object/life_support.cpp b/src/object/life_support.cpp
index 9f7645de..f4bc7b80 100644
--- a/src/object/life_support.cpp
+++ b/src/object/life_support.cpp
@@ -80,7 +80,7 @@ PyTypeObject life_support_type = {
 
 PyObject* make_nurse_and_patient(PyObject* nurse, PyObject* patient)
 {
-    if (nurse == Py_None)
+    if (nurse == Py_None || nurse == patient)
         return nurse;
     
     if (life_support_type.ob_type == 0)
diff --git a/src/wrapper.cpp b/src/wrapper.cpp
new file mode 100755
index 00000000..eac7d972
--- /dev/null
+++ b/src/wrapper.cpp
@@ -0,0 +1,65 @@
+// Copyright David Abrahams 2004. Distributed under the Boost
+// Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/python/wrapper.hpp>
+
+namespace boost { namespace python {
+
+namespace detail
+{
+  override wrapper_base::get_override(
+      char const* name
+    , PyTypeObject* class_object
+  ) const
+  {
+      if (this->m_self)
+      {
+          if (handle<> m = handle<>(
+                  python::allow_null(
+                      ::PyObject_GetAttrString(
+                          this->m_self, const_cast<char*>(name))))
+          )
+          {
+              PyObject* borrowed_f = 0;
+            
+              if (
+                  PyMethod_Check(m.get())
+                  && ((PyMethodObject*)m.get())->im_self == this->m_self
+                  && class_object->tp_dict != 0
+              )
+              {
+                  borrowed_f = ::PyDict_GetItemString(class_object->tp_dict, name);
+
+
+              }
+              if (borrowed_f != ((PyMethodObject*)m.get())->im_func)
+                  return override(m);
+          }
+      }
+      return override(handle<>(detail::none()));
+  }
+}
+
+#if 0
+namespace converter
+{
+  PyObject* BOOST_PYTHON_DECL do_polymorphic_ref_to_python(
+      python::detail::wrapper_base const volatile* x, type_info src
+  )
+  {
+      if (x == 0)
+      {
+          ::PyErr_Format(
+              PyExc_TypeError
+            , "Attempting to returning pointer or reference to instance of %s\n"
+              "for which no corresponding Python object exists. Wrap this function"
+              "with a return return value policy"
+          )
+      }
+  }
+  
+}
+#endif 
+
+}} // namespace boost::python::detail
diff --git a/test/Jamfile b/test/Jamfile
index 1a1e663d..32dc054f 100644
--- a/test/Jamfile
+++ b/test/Jamfile
@@ -99,6 +99,7 @@ bpl-test crossmod_exception
 [ bpl-test staticmethod ]
 [ bpl-test shared_ptr ]
 [ bpl-test polymorphism ]
+[ bpl-test polymorphism2 ]
 [ bpl-test auto_ptr ]
 [ bpl-test minimal ]
 [ bpl-test args ]
diff --git a/test/embedding.cpp b/test/embedding.cpp
index d280a163..d2bd021a 100644
--- a/test/embedding.cpp
+++ b/test/embedding.cpp
@@ -74,7 +74,7 @@ void test()
     )();
 
     // Retrieve the main module's namespace
-    python::object main_namespace(main_module.attr("__dict__"));
+    python::object main_namespace((main_module.attr("__dict__")));
 
     // Define the derived class in Python.
     // (You'll normally want to put this in a .py file.)
@@ -115,12 +115,12 @@ test_tutorial()
 {
     using namespace boost::python;
 
-    object main_module(
-        handle<>(borrowed(PyImport_AddModule("__main__"))));
+    object main_module((
+        handle<>(borrowed(PyImport_AddModule("__main__")))));
 
     object main_namespace = main_module.attr("__dict__");
 
-    handle<>(PyRun_String(
+    handle<> ignored((PyRun_String(
 
         "hello = file('hello.txt', 'w')\n"
         "hello.write('Hello world!')\n"
@@ -129,7 +129,7 @@ test_tutorial()
       , Py_file_input
       , main_namespace.ptr()
       , main_namespace.ptr())
-    );
+    ));
 }
 
 void
@@ -137,29 +137,29 @@ test_tutorial2()
 {
     using namespace boost::python;
 
-    object main_module(
-        handle<>(borrowed(PyImport_AddModule("__main__"))));
+    object main_module((
+         handle<>(borrowed(PyImport_AddModule("__main__")))));
 
     object main_namespace = main_module.attr("__dict__");
 
-    handle<>(PyRun_String(
+    handle<> ignored((PyRun_String(
 
         "result = 5 ** 2"
 
         , Py_file_input
         , main_namespace.ptr()
         , main_namespace.ptr())
-    );
+    ));
 
     int five_squared = extract<int>(main_namespace["result"]);
     assert(five_squared == 25);
 
-    object result(handle<>(
+    object result((handle<>(
         PyRun_String("5 ** 2"
             , Py_eval_input
             , main_namespace.ptr()
             , main_namespace.ptr()))
-    );
+    ));
 
     int five_squared2 = extract<int>(result);
     assert(five_squared2 == 25);
diff --git a/test/polymorphism2.cpp b/test/polymorphism2.cpp
new file mode 100755
index 00000000..13e8ab4d
--- /dev/null
+++ b/test/polymorphism2.cpp
@@ -0,0 +1,159 @@
+// Copyright David Abrahams 2002. Permission to copy, use,
+// modify, sell and distribute this software is granted provided this
+// copyright notice appears in all copies. This software is provided
+// "as is" without express or implied warranty, and with no claim as
+// to its suitability for any purpose.
+#include <boost/python/module.hpp>
+#include <boost/python/class.hpp>
+#include <boost/python/return_value_policy.hpp>
+#include <boost/python/manage_new_object.hpp>
+#include <boost/python/reference_existing_object.hpp>
+#include <boost/python/pure_virtual.hpp>
+#include <boost/python/wrapper.hpp>
+#include <boost/python/def.hpp>
+#include <boost/python/call.hpp>
+#include <boost/utility.hpp>
+
+using namespace boost::python;
+
+struct P
+{
+    virtual ~P(){}
+    virtual char const* f() = 0;
+    char const* g() { return "P::g()"; }
+};
+
+struct PCallback : P, wrapper<P>
+{
+    char const* f()
+    {
+#if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
+        return call<char const*>(this->get_override("f").ptr());
+#else 
+        return this->get_override("f")();
+#endif 
+    }
+};
+
+struct Q : virtual P
+{
+    char const* f() { return "Q::f()"; } 
+};
+
+struct A
+{
+    virtual ~A(){}
+    virtual char const* f() { return "A::f()"; }
+};
+
+struct ACallback :  A, wrapper<A>
+{
+    char const* f()
+    {
+        if (override f = this->get_override("f"))
+#if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
+            return call<char const*>(f.ptr());
+#else 
+            return f();
+#endif 
+        else
+            return A::f();
+    }
+};
+
+struct B : A
+{
+    virtual char const* f() { return "B::f()"; } 
+};
+
+struct C : A
+{
+    virtual char const* f() { return "C::f()"; }
+};
+
+struct D : A
+{
+    virtual char const* f() { return "D::f()"; }
+    char const* g() { return "D::g()"; }
+};
+
+struct DCallback :  D,  wrapper<D>
+{
+    char const* f()
+    {
+        if (override f = this->get_override("f"))
+#if BOOST_WORKAROUND(BOOST_MSVC, <= 1300)
+            return call<char const*>(f.ptr());
+#else 
+            return f();
+#endif 
+        else
+            return D::f();
+    }
+};
+
+    
+A& getBCppObj ()
+{
+    static B b;
+    return b;
+}
+
+char const* call_f(A& a) { return a.f(); }
+
+A* factory(unsigned choice)
+{
+    switch (choice % 3)
+    {
+    case 0: return new A;
+        break;
+    case 1: return new B;
+        break;
+    default: return new C;
+        break;
+    }
+}
+
+C& getCCppObj ()
+{
+    static C c;
+    return c;
+}
+
+A* pass_a(A* x) { return x; }
+
+BOOST_PYTHON_MODULE_INIT(polymorphism2_ext)
+{
+    class_<ACallback,boost::noncopyable>("A")
+        .def("f", &A::f)
+        ;
+    
+    def("getBCppObj", getBCppObj, return_value_policy<reference_existing_object>());
+
+    class_<C,bases<A>,boost::noncopyable>("C")
+        .def("f", &C::f)
+        ;
+    
+    class_<DCallback,bases<A>,boost::noncopyable>("D")
+        .def("f", &D::f)
+        .def("g", &D::g)
+        ;
+
+    def("pass_a", &pass_a,  return_internal_reference<>());
+    
+    def("getCCppObj", getCCppObj, return_value_policy<reference_existing_object>());
+
+    def("factory", factory, return_value_policy<manage_new_object>());
+
+    def("call_f", call_f);
+
+    class_<PCallback,boost::noncopyable>("P")
+        .def("f", pure_virtual(&P::f))
+        ;
+
+    class_<Q, bases<P> >("Q")
+        .def("g", &P::g) // make sure virtual inheritance doesn't interfere
+        ;
+}
+
+//#include "module_tail.cpp"
diff --git a/test/polymorphism2.py b/test/polymorphism2.py
new file mode 100644
index 00000000..79d87b37
--- /dev/null
+++ b/test/polymorphism2.py
@@ -0,0 +1,71 @@
+import unittest
+from polymorphism2_ext import *
+
+class PolymorphTest(unittest.TestCase):
+
+   def testReturnCpp(self):
+
+      # Python Created Object With Same Id As
+      # Cpp Created B Object 
+      # b = B(872)  
+
+      #  Get Reference To Cpp Created B Object
+      a = getBCppObj()
+
+      # Python Created B Object and Cpp B Object
+      # Should have same result by calling f()
+      self.failUnlessEqual ('B::f()', a.f())
+      self.failUnlessEqual ('B::f()', call_f(a))
+      self.failUnlessEqual ('A::f()', call_f(A()))
+
+   def test_references(self):
+      # B is not exposed to Python
+      a = getBCppObj()
+      self.failUnlessEqual(type(a), A)
+
+      # C is exposed to Python
+      c = getCCppObj()
+      self.failUnlessEqual(type(c), C)
+      
+   def test_factory(self):
+      self.failUnlessEqual(type(factory(0)), A)
+      self.failUnlessEqual(type(factory(1)), A)
+      self.failUnlessEqual(type(factory(2)), C)
+
+   def test_return_py(self):
+
+      class X(A):
+         def f(self):
+            return 'X.f'
+
+      x = X()
+      
+      self.failUnlessEqual ('X.f', x.f())
+      self.failUnlessEqual ('X.f', call_f(x))
+
+   def test_wrapper_downcast(self):
+      a = pass_a(D())
+      self.failUnlessEqual('D::g()', a.g())
+
+   def test_pure_virtual(self):
+      p = P()
+      self.assertRaises(RuntimeError, p.f)
+      
+      q = Q()
+      self.failUnlessEqual ('Q::f()', q.f())
+      
+      class R(P):
+         def f(self):
+            return 'R.f'
+
+      r = R()
+      self.failUnlessEqual ('R.f', r.f())
+      
+                        
+if __name__ == "__main__":
+   
+   # remove the option which upsets unittest
+   import sys
+   sys.argv = [ x for x in sys.argv if x != '--broken-auto-ptr' ]
+   
+   unittest.main()