[boost] [move] Declarations of the copy constructor and copy-assign operator produced by BOOST_MOVABLE_BUT_NOT_COPYABLE

Subject: [boost] [move] Declarations of the copy constructor and copy-assign operator produced by BOOST_MOVABLE_BUT_NOT_COPYABLE
From: Joseph Trebbien (jtrebbien_at_[hidden])
Date: 2011-04-14 12:23:37

Looking through the sources of Boost.Move in trunk, I am wondering
about a couple of lines in <boost/move/move.hpp> that are part of the
expansion of BOOST_MOVABLE_BUT_NOT_COPYABLE when
BOOST_NO_RVALUE_REFERENCES is defined:

#define BOOST_MOVABLE_BUT_NOT_COPYABLE(TYPE)\
   private:\
   TYPE(TYPE &);\
   TYPE& operator=(TYPE &);\
   public:\
   operator ::boost::rv<TYPE>&() \
   {  return *static_cast< ::boost::rv<TYPE>* >(this);  }\
   operator const ::boost::rv<TYPE>&() const \
   {  return *static_cast<const ::boost::rv<TYPE>* >(this);  }\
   private:\
//

Why do the declarations of the copy constructor and copy-assign
operator overload not take a const-reference to TYPE?  When
BOOST_NO_RVALUE_REFERENCES is not defined, they do:

#define BOOST_MOVABLE_BUT_NOT_COPYABLE(TYPE)\
   public:\
   typedef int boost_move_emulation_t;\
   private:\
   TYPE(const TYPE &);\
   TYPE& operator=(const TYPE &);\
//

Joseph Trebbien