Still further rationalized conversion registry

[SVN r14462]

src/converter/arg_to_python_base.cpp

@@ -0,0 +1,58 @@
+// 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/converter/arg_to_python_base.hpp>
+#include <boost/python/errors.hpp>
+#include <boost/python/converter/registrations.hpp>
+#include <boost/python/handle.hpp>
+#include <boost/python/refcount.hpp>
+
+namespace boost { namespace python { namespace converter { 
+
+namespace
+{
+    inline PyObject* convert_to_python(void const volatile* source, registration const& converters)
+    {
+        if (converters.to_python == 0)
+        {
+            handle<> msg(
+                ::PyString_FromFormat(
+                    "No to_python (by-value) converter found for C++ type: %s"
+                    , converters.target_type.name()));
+            
+            PyErr_SetObject(PyExc_TypeError, msg.get());
+
+            throw_error_already_set();
+        }
+        
+        return source == 0
+            ? incref(Py_None)
+            : converters.to_python(const_cast<void*>(source));
+    }
+}
+
+namespace detail
+{
+  arg_to_python_base::arg_to_python_base(
+      void const volatile* source, registration const& converters)
+# if !defined(BOOST_MSVC) || _MSC_FULL_VER != 13102140
+      : handle<>(converter::convert_to_python(source, converters))
+# else
+      : m_ptr(converter::convert_to_python(source, converters))
+# endif 
+  {
+  }
+
+  BOOST_PYTHON_DECL void throw_no_class_registered()
+  {
+      PyErr_SetString(
+          PyExc_TypeError
+          , const_cast<char*>("class not registered for to_python type"));
+      throw_error_already_set();
+  }
+}
+
+}}} // namespace boost::python::converter