The BOOST_PP_LIST_TO_ARRAY_D macro
      converts a list to an array. It reenters BOOST_PP_WHILE
      with maximum efficiency. 
     Usage 
     BOOST_PP_LIST_TO_ARRAY_D(d, list)
    
     Arguments 
    
      - d
- The next available BOOST_PP_WHILE iteration.
- list
-  The list to be converted. 
Remarks
        If the list to be converted is empty, as
      represented by 'BOOST_PP_NIL', the resulting array is empty, as
      represented by '( 0, () )'. 
    See Also
    See Also
    
     Requirements