From bcaa1043ea9ae1f0ed052079d6220d066fd63c57 Mon Sep 17 00:00:00 2001
From: Dave Abrahams <dave@boostpro.com>
Date: Fri, 23 Aug 2002 18:07:27 +0000
Subject: [PATCH] More smart pointer handling

[SVN r15069]
---
 include/boost/python/class.hpp                | 10 +++--
 include/boost/python/instance_holder.hpp      |  4 ++
 include/boost/python/object/class_wrapper.hpp | 40 ++++++++++---------
 .../boost/python/object/pointer_holder.hpp    | 40 +++++++++++++++++--
 include/boost/python/object/value_holder.hpp  | 13 +++++-
 test/m1.cpp                                   | 10 ++++-
 test/newtest.py                               |  7 ++++
 7 files changed, 97 insertions(+), 27 deletions(-)

diff --git a/include/boost/python/class.hpp b/include/boost/python/class.hpp
index 870f644c..1e75a6f5 100644
--- a/include/boost/python/class.hpp
+++ b/include/boost/python/class.hpp
@@ -52,15 +52,17 @@ namespace detail
   // to the type of holder that must be created. The 3rd argument is a
   // reference to the Python type object to be created.
   template <class T, class Holder>
-  static inline void register_copy_constructor(mpl::bool_t<true> const&, Holder*, object const& obj, T* = 0)
+  static inline void register_copy_constructor(mpl::bool_t<true> const&, Holder*, T* = 0)
   {
-      objects::class_wrapper<T,Holder> x(obj);
+      force_instantiate(objects::class_wrapper<T,Holder>());
+      Holder::register_();
   }
 
   // Tag dispatched to have no effect.
   template <class T, class Holder>
-  static inline void register_copy_constructor(mpl::bool_t<false> const&, Holder*, object const&, T* = 0)
+  static inline void register_copy_constructor(mpl::bool_t<false> const&, Holder*, T* = 0)
   {
+      Holder::register_();
   }
 
   template <class T> int assert_default_constructible(T const&);
@@ -331,7 +333,7 @@ inline void class_<T,X1,X2,X3>::register_() const
     detail::register_copy_constructor<T>(
         mpl::bool_t<is_copyable>()
         , objects::select_holder<T,held_type>((held_type*)0).get()
-        , *this);
+        );
 }
 
 
diff --git a/include/boost/python/instance_holder.hpp b/include/boost/python/instance_holder.hpp
index eb148431..f4962479 100755
--- a/include/boost/python/instance_holder.hpp
+++ b/include/boost/python/instance_holder.hpp
@@ -24,6 +24,10 @@ struct BOOST_PYTHON_DECL instance_holder : private noncopyable
     virtual void* holds(type_info) = 0;
 
     void install(PyObject* inst) throw();
+
+    // Register any converters associated with this Holder
+    static inline void register_() {}
+    
  private:
     instance_holder* m_next;
 };
diff --git a/include/boost/python/object/class_wrapper.hpp b/include/boost/python/object/class_wrapper.hpp
index 2e06f921..723126a4 100644
--- a/include/boost/python/object/class_wrapper.hpp
+++ b/include/boost/python/object/class_wrapper.hpp
@@ -8,26 +8,37 @@
 
 # include <boost/python/handle.hpp>
 # include <boost/python/to_python_converter.hpp>
+# include <boost/python/converter/registered.hpp>
+# include <boost/ref.hpp>
 
 namespace boost { namespace python { namespace objects { 
 
-template <class T, class Holder>
-struct class_wrapper
-    : to_python_converter<T,class_wrapper<T,Holder> >
+template <class Src, class Holder>
+struct copy_construct_instance
 {
-    class_wrapper(object const& type_)
-        : m_class_object_keeper(type_)
+    static Holder* execute(PyObject* instance, Src const& x)
     {
-        assert(type_.ptr()->ob_type == (PyTypeObject*)class_metatype().get());
-        m_class_object = (PyTypeObject*)type_.ptr();
+        return new Holder(instance, cref(x));
     }
-    
-    static PyObject* convert(T const& x)
+};
+
+// Used to convert objects of type Src to wrapped C++ classes by
+// building a new instance object and installing a Holder constructed
+// from the Src object.
+template <class Src, class Holder, class MakeHolder = copy_construct_instance<Src,Holder> >
+struct class_wrapper
+    : to_python_converter<Src,class_wrapper<Src,Holder,MakeHolder> >
+{
+    static PyObject* convert(Src const& x)
     {
+        // Get the class object associated with the wrapped type
+        typedef typename Holder::value_type value_type;
+        PyTypeObject* class_object = converter::registered<value_type>::converters.class_object;
+        
         // Don't call the type directly to do the construction, since
         // that would require the registration of an appropriate
         // __init__ function.
-        PyObject* raw_result = m_class_object->tp_alloc(m_class_object, 0);
+        PyObject* raw_result = class_object->tp_alloc(class_object, 0);
 
         if (raw_result == 0)
             return 0;
@@ -38,7 +49,7 @@ struct class_wrapper
 
         // Build a value_holder to contain the object using the copy
         // constructor
-        Holder* p = new Holder(raw_result, cref(x));
+        Holder* p = MakeHolder::execute(raw_result, x);
 
         // Install it in the instance
         p->install(raw_result);
@@ -46,15 +57,8 @@ struct class_wrapper
         // Return the new result
         return result.release();
     }
-    
- private:
-    object m_class_object_keeper;
-    static PyTypeObject* m_class_object;
 };
 
-template <class T, class Holder>
-PyTypeObject* class_wrapper<T,Holder>::m_class_object;
-
 }}} // namespace boost::python::objects
 
 #endif // CLASS_WRAPPER_DWA20011221_HPP
diff --git a/include/boost/python/object/pointer_holder.hpp b/include/boost/python/object/pointer_holder.hpp
index 8498a8df..3d9e9992 100644
--- a/include/boost/python/object/pointer_holder.hpp
+++ b/include/boost/python/object/pointer_holder.hpp
@@ -16,6 +16,7 @@
 #  include <boost/python/object/inheritance.hpp>
 #  include <boost/python/object/find_instance.hpp>
 #  include <boost/python/object/forward.hpp>
+#  include <boost/python/object/class_wrapper.hpp>
 #  include <boost/python/pointee.hpp>
 #  include <boost/python/detail/force_instantiate.hpp>
 #  include <boost/python/detail/preprocessor.hpp>
@@ -34,13 +35,26 @@ namespace boost { namespace python { namespace objects {
 template <class Pointer, class Value>
 struct pointer_holder : instance_holder
 {
+    typedef Value value_type;
+    
     pointer_holder(Pointer);
 
+    static void register_();
+
     // Forward construction to the held object
 
 #  define BOOST_PP_ITERATION_PARAMS_1 (4, (0, BOOST_PYTHON_MAX_ARITY, <boost/python/object/pointer_holder.hpp>, 1))
 #  include BOOST_PP_ITERATE()
 
+ private: // types
+    struct construct_from_pointer
+    {
+        static pointer_holder* execute(PyObject*, Pointer x)
+        {
+            return new pointer_holder(x);
+        }
+    };
+    
  private: // required holder implementation
     void* holds(type_info);
 
@@ -54,9 +68,14 @@ struct pointer_holder_back_reference : instance_holder
  private:
     typedef typename python::pointee<Pointer>::type held_type;
  public:
+    typedef Value value_type;
 
+    // Not sure about this one -- can it work? The source object
+    // undoubtedly does not carry the correct back reference pointer.
     pointer_holder_back_reference(Pointer);
 
+    static void register_();
+    
     // Forward construction to the held object
 #  define BOOST_PP_ITERATION_PARAMS_1 (4, (0, BOOST_PYTHON_MAX_ARITY, <boost/python/object/pointer_holder.hpp>, 2))
 #  include BOOST_PP_ITERATE()
@@ -76,12 +95,29 @@ inline pointer_holder<Pointer,Value>::pointer_holder(Pointer p)
 {
 }
 
+template <class Pointer, class Value>
+inline void pointer_holder<Pointer,Value>::register_()
+{
+    python::detail::force_instantiate(class_wrapper<Pointer,pointer_holder,construct_from_pointer>());
+    python::detail::force_instantiate(instance_finder<Pointer>::registration);
+}
+    
+
 template <class Pointer, class Value>
 inline pointer_holder_back_reference<Pointer,Value>::pointer_holder_back_reference(Pointer p)
     : m_p(p)
 {
 }
 
+template <class Pointer, class Value>
+inline void pointer_holder_back_reference<Pointer,Value>::register_()
+{
+    // not implemented at least until we solve the back reference issue mentioned above.
+    //    python::detail::force_instantiate(class_wrapper<Pointer,pointer_holder_back_reference>());
+    python::detail::force_instantiate(instance_finder<Pointer>::registration);
+    python::detail::force_instantiate(instance_finder<held_type>::registration);
+}
+
 template <class Pointer, class Value>
 void* pointer_holder<Pointer, Value>::holds(type_info dst_t)
 {
@@ -142,9 +178,7 @@ void* pointer_holder_back_reference<Pointer, Value>::holds(type_info dst_t)
         : m_p(new held_type(
                     p BOOST_PP_COMMA_IF(N) BOOST_PP_REPEAT(N, BOOST_PYTHON_UNFORWARD_LOCAL, nil)
             ))
-    {
-        python::detail::force_instantiate(instance_finder<held_type>::registration);
-    }
+    {}
 
 # undef N
 
diff --git a/include/boost/python/object/value_holder.hpp b/include/boost/python/object/value_holder.hpp
index 6eb0c4ed..3d8d2ac2 100644
--- a/include/boost/python/object/value_holder.hpp
+++ b/include/boost/python/object/value_holder.hpp
@@ -29,6 +29,8 @@ namespace boost { namespace python { namespace objects {
 template <class Held>
 struct value_holder : instance_holder
 {
+    typedef Held value_type;
+
     // Forward construction to the held object
 #  define BOOST_PP_ITERATION_PARAMS_1 (4, (0, BOOST_PYTHON_MAX_ARITY, <boost/python/object/value_holder.hpp>, 1))
 #  include BOOST_PP_ITERATE()
@@ -43,6 +45,10 @@ struct value_holder : instance_holder
 template <class Held, class BackReferenceType>
 struct value_holder_back_reference : instance_holder
 {
+    typedef Held value_type;
+    
+    static void register_();
+    
     // Forward construction to the held object
 #  define BOOST_PP_ITERATION_PARAMS_1 (4, (0, BOOST_PYTHON_MAX_ARITY, <boost/python/object/value_holder.hpp>, 2))
 #  include BOOST_PP_ITERATE()
@@ -79,6 +85,12 @@ void* value_holder_back_reference<Held,BackReferenceType>::holds(
         return find_static_type(x, src_t, dst_t);
 }
 
+template <class Held, class BackReferenceType>
+void value_holder_back_reference<Held,BackReferenceType>::register_()
+{
+    python::detail::force_instantiate(instance_finder<BackReferenceType>::registration);
+}
+
 }}} // namespace boost::python::objects
 
 # endif // VALUE_HOLDER_DWA20011215_HPP
@@ -119,7 +131,6 @@ void* value_holder_back_reference<Held,BackReferenceType>::holds(
             BOOST_PP_REPEAT(N, BOOST_PYTHON_UNFORWARD_LOCAL, nil)
             )
     {
-        python::detail::force_instantiate(instance_finder<BackReferenceType>::registration);
     }
 
 # undef N
diff --git a/test/m1.cpp b/test/m1.cpp
index de76f64a..34832dfa 100644
--- a/test/m1.cpp
+++ b/test/m1.cpp
@@ -190,7 +190,11 @@ A take_a(A const& a) { return a; }
 B take_b(B& b) { return b; }
 C take_c(C* c) { return *c; }
 D take_d(D* const& d) { return *d; }
-    
+
+D take_d_shared_ptr(boost::shared_ptr<D> d) { return *d; }
+
+boost::shared_ptr<A> d_factory() { return boost::shared_ptr<B>(new D); }
+
 BOOST_PYTHON_MODULE_INIT(m1)
 {
     using namespace boost::python;
@@ -237,6 +241,10 @@ BOOST_PYTHON_MODULE_INIT(m1)
       .def("take_b", take_b)
       .def("take_c", take_c)
       .def("take_d", take_d)
+
+
+      .def("take_d_shared_ptr", take_d_shared_ptr)
+      .def("d_factory", d_factory)
         ;
 
     class_<A, shared_ptr<A> >("A")
diff --git a/test/newtest.py b/test/newtest.py
index 0edd34b8..7b68a260 100644
--- a/test/newtest.py
+++ b/test/newtest.py
@@ -158,6 +158,13 @@ are a complicated constructor and member function, respectively.
 >>> take_d(d).name()
 'D'
 
+>>> take_d_shared_ptr(d).name()
+'D'
+
+>>> d_as_a = d_factory()
+>>> dd = take_d(d_as_a)
+>>> dd.name()
+'D'
 
 """