[C++-sig] Re: boost::python::range and duplicate comdat under MSVC 6

[Raoul Gough]

David Abrahams <dave at boost-consulting.com> writes:

> Raoul Gough <RaoulGough at yahoo.co.uk> writes:
>
>>> However, a simple transformation ought to be enough to eliminate the
>>> static data member, AFAICT.  Do you need help working it out?
>>
>> It looks to me like the static member is only useful for the
>> side-effects of its constructor. Is there an alternative way to
>> achieve this?
>
> Sure; use a function-static variable in the constructor to make sure
> that the side-effects only happen once, and then change
> class_converters.hpp so that it constructs a shared_ptr_from_python
> on the stack instead of calling force_instantiate.

OK, I've gone with a static variable in register_class_from_python to
force construction of the shared_ptr_from_python. This is wrapped in
MSVC6 workaround guards, so that other compilers still use a
class-static variable. No real reason for doing this, except that it
would probably affect the initialization order on other platforms
unnecessarily, and I just like to minimize the impact of fixes.

Patches follow. OK to commit these on the CVS mainline?


$ cvs diff -c boost/python/converter/shared_ptr_from_python.hpp boost/python/object/class_converters.hpp
Index: boost/python/converter/shared_ptr_from_python.hpp
===================================================================
RCS file: /cvsroot/boost/boost/boost/python/converter/shared_ptr_from_python.hpp,v
retrieving revision 1.1
diff -c -r1.1 shared_ptr_from_python.hpp
*** boost/python/converter/shared_ptr_from_python.hpp	2 Dec 2002 01:37:39 -0000	1.1
--- boost/python/converter/shared_ptr_from_python.hpp	10 Nov 2003 17:34:53 -0000
***************
*** 8,13 ****
--- 8,14 ----
  
  # include <boost/python/handle.hpp>
  # include <boost/python/converter/shared_ptr_deleter.hpp>
+ # include <boost/detail/workaround.hpp>
  
  namespace boost { namespace python { namespace converter { 
  
***************
*** 19,25 ****
--- 20,29 ----
          converter::registry::insert(&convertible, &construct, type_id<shared_ptr<T> >());
      }
  
+ # if !BOOST_WORKAROUND (BOOST_MSVC, == 1200)
+     // This static var can cause duplicate comdat link errors with MSVC6
      static shared_ptr_from_python const registration;
+ # endif
   private:
      static void* convertible(PyObject* p)
      {
***************
*** 45,52 ****
--- 49,58 ----
      }
  };
  
+ # if !BOOST_WORKAROUND (BOOST_MSVC, == 1200)
  template <class T>
  shared_ptr_from_python<T> const shared_ptr_from_python<T>::registration;
+ # endif
  
  }}} // namespace boost::python::converter
  
Index: boost/python/object/class_converters.hpp
===================================================================
RCS file: /cvsroot/boost/boost/boost/python/object/class_converters.hpp,v
retrieving revision 1.15
diff -c -r1.15 class_converters.hpp
*** boost/python/object/class_converters.hpp	21 May 2003 22:17:23 -0000	1.15
--- boost/python/object/class_converters.hpp	10 Nov 2003 17:34:53 -0000
***************
*** 18,23 ****
--- 18,25 ----
  
  # include <boost/mpl/for_each.hpp>
  
+ # include <boost/detail/workaround.hpp>
+ 
  namespace boost { namespace python { namespace objects { 
  
  //////////////////////////////////////////////////////////////////////
***************
*** 76,83 ****
  template <class Derived, class Bases>
  inline void register_class_from_python(Derived* = 0, Bases* = 0)
  {
      python::detail::force_instantiate(converter::shared_ptr_from_python<Derived>::registration);
!     
      // register all up/downcasts here
      register_dynamic_id<Derived>();
  
--- 78,90 ----
  template <class Derived, class Bases>
  inline void register_class_from_python(Derived* = 0, Bases* = 0)
  {
+ # if BOOST_WORKAROUND (BOOST_MSVC, == 1200)
+     // Avoids duplicate comdat link errors with MSVC6
+     static converter::shared_ptr_from_python<Derived> shared_ptr_registration;
+ # else
      python::detail::force_instantiate(converter::shared_ptr_from_python<Derived>::registration);
! # endif
! 
      // register all up/downcasts here
      register_dynamic_id<Derived>();

-- 
Raoul Gough.
(setq dabbrev-case-fold-search nil)