Re: [boost] [preprocessor] [variadic] VMD_SIZE using ADD -- why?

Subject: Re: [boost] [preprocessor] [variadic] VMD_SIZE using ADD -- why?
From: lcaminiti (lorcaminiti_at_[hidden])
Date: 2011-06-06 13:27:40

lcaminiti wrote:
> 
> BTW, why is PP_ADD(size, 0) used on MSVC? If this is just for forcing
> proper macro expansion, I think other techniques (like the ones used by
> PP_EXPAND) should be used so no PP_WHILE reentrancy dependency is
> introduced.
> 

For example, something like this should work instead of using PP_ADD(size,
0):

#if defined(BOOST_MSVC)
#  if ~BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MWCC() &&
~BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_DMC()
#    define BOOST_DETAIL_PP_VMD_DETAIL_DATA_SIZE_EXPAND(x)
BOOST_DETAIL_PP_VMD_DETAIL_DATA_SIZE_EXPAND_I(x)
#  else
#    define BOOST_DETAIL_PP_VMD_DETAIL_DATA_SIZE_EXPAND(x)
BOOST_DETAIL_PP_VMD_DETAIL_DATA_SIZE_EXPAND_OO((x))
#    define BOOST_DETAIL_PP_VMD_DETAIL_DATA_SIZE_EXPAND_OO(par)
BOOST_DETAIL_PP_VMD_DETAIL_DATA_SIZE_EXPAND_I ## par
#  endif
#  define BOOST_DETAIL_PP_VMD_DETAIL_DATA_SIZE_EXPAND_I(x) x
#define BOOST_DETAIL_PP_VMD_DETAIL_DATA_SIZE(...) \
 
BOOST_DETAIL_PP_VMD_DETAIL_DATA_SIZE_EXPAND(BOOST_DETAIL_PP_VMD_DETAIL_APPLY(BOOST_DETAIL_PP_VMD_DETAIL_ARG_N,
(__VA_ARGS__, BOOST_DETAIL_PP_VMD_DETAIL_RSEQ_N()))) \
/**/
#else
#define BOOST_DETAIL_PP_VMD_DETAIL_DATA_SIZE(...) \
  BOOST_DETAIL_PP_VMD_DETAIL_APPLY(BOOST_DETAIL_PP_VMD_DETAIL_ARG_N,
(__VA_ARGS__, BOOST_DETAIL_PP_VMD_DETAIL_RSEQ_N())) \
/**/
#endif

--Lorenzo

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