From f2e34d4836eab58dfd123b1aba294f5ed1d799fe Mon Sep 17 00:00:00 2001
From: Dave Abrahams <dave@boostpro.com>
Date: Mon, 30 Jul 2001 13:31:23 +0000
Subject: [PATCH] MSVC doesn't like boost::dereferencable<T> unless T has a
 default constructor, so operator-> must be defined by hand

[SVN r10720]
---
 include/boost/python/detail/cast.hpp | 7 ++++++-
 include/boost/python/reference.hpp   | 9 ++++++---
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/include/boost/python/detail/cast.hpp b/include/boost/python/detail/cast.hpp
index a6f2f046..e047c0b3 100644
--- a/include/boost/python/detail/cast.hpp
+++ b/include/boost/python/detail/cast.hpp
@@ -51,7 +51,7 @@ inline PyObject* as_object(PyTypeObject* p) { return reinterpret_cast<PyObject*>
 // If I didn't have to support stupid MSVC6 we could just use a simple template function:
 // template <class T> T* downcast(PyObject*).
 template <class T>
-struct downcast : boost::dereferenceable<downcast<T>, T*>
+struct downcast
 {
     downcast(PyObject* p)
         : m_p(detail::downcast_traits<T>::cast(detail::as_base_object((T*)0, p)))
@@ -70,6 +70,11 @@ struct downcast : boost::dereferenceable<downcast<T>, T*>
         {}
     
     operator T*() const { return m_p; }
+
+    // MSVC doesn't like boost::dereferencable unless T has a default
+    // constructor, so operator-> must be defined by hand :(
+    T* operator->() const { return &**this; }
+    
     T* get() const { return m_p; }
     T& operator*() const { return *m_p; }
  private:
diff --git a/include/boost/python/reference.hpp b/include/boost/python/reference.hpp
index c633b9d7..a1585099 100644
--- a/include/boost/python/reference.hpp
+++ b/include/boost/python/reference.hpp
@@ -20,7 +20,7 @@
 
 BOOST_PYTHON_BEGIN_CONVERSION_NAMESPACE
 
-template <class T, class Value, class Base>
+template <class T, class Value, class Base = boost::detail::empty_base>
 struct py_ptr_conversions : Base
 {
     inline friend T from_python(PyObject* x, boost::python::type<const T&>)
@@ -42,8 +42,7 @@ BOOST_PYTHON_IMPORT_CONVERSION(py_ptr_conversions);
 
 template <class T>
 class reference
-	: public py_ptr_conversions<reference<T>, T,
-       boost::dereferenceable<reference<T>, T*> > // supplies op->
+	: public py_ptr_conversions<reference<T>, T>
 {
 public:
     typedef T value_type;
@@ -117,6 +116,10 @@ public:
 	
 	T& operator*() const { return *m_p; }
     
+    // MSVC doesn't like boost::dereferencable unless T has a default
+    // constructor, so operator-> must be defined by hand :(
+    T* operator->() const { return &**this; } 
+    
 	T* get() const { return m_p; }
 
 	T* release()