Re: [Boost-bugs] [Boost C++ Libraries] #2472: ptr_sequence_adapter<T>::sort fails to compile if T is an abstract base class

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #2472: ptr_sequence_adapter<T>::sort fails to compile if T is an abstract base class
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-11-06 00:06:20

#2472: ptr_sequence_adapter<T>::sort fails to compile if T is an abstract base
class
---------------------------+------------------------------------------------
  Reporter:  anonymous     |       Owner:  nesotto      
      Type:  Bugs          |      Status:  new          
 Milestone:  Boost 1.38.0  |   Component:  ptr_container
   Version:  Boost 1.36.0  |    Severity:  Problem      
Resolution:                |    Keywords:               
---------------------------+------------------------------------------------

Comment(by annonymous):

 Okay, so this isn't a  problem with ptr_container per-se but rather a bug
 with MSVC, which might also manifest itself in other parts of the library.
 I'm posting a workaround that should fix the problem, but I still believe
 it should be taken into account and fixed in a future release.


 {{{
 //
 ---------------------------------------------------------------------------------------
 //  Fix for a bug in MSVC++ that made sort fail on ptr_containers which
 held pointers
 //  to abstract types. Include and use sort_ptr_container(ptr_container [,
 function]).
 //  Thanks goes to Dodheim who originally came up with this fix :-)
 //
 ---------------------------------------------------------------------------------------

 #include <algorithm>
 #include <boost/type_traits/remove_pointer.hpp>

 template<typename Fun, typename Arg>
 class indirect_compare
 {
 private:
         Fun fun;
 public:
         typedef bool result_type;
         indirect_compare() : fun(Fun()) {}
         indirect_compare(Fun f) : fun(f) {}
         result_type operator ()(const void* lhs, const void* rhs) const
         {
                 return fun(*static_cast<const Arg*>(lhs),
 *static_cast<const Arg*>(rhs));
         }
 };

 template<typename container_t>
 void sort_ptr_container(container_t& container)
 {
         typedef typename boost::remove_pointer<typename
 container_t::value_type>::type Arg;
         sort_ptr_container(container, std::less<Arg>());
 }

 template<typename container_t, typename Fun>
 void sort_ptr_container(container_t& container, Fun f)
 {
         typedef typename boost::remove_pointer<typename
 container_t::value_type>::type Arg;
         std::sort(container.begin().base(), container.end().base(),
 indirect_compare<Fun, Arg>(f));
 }
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/2472#comment:1>
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