Daniel James wrote:
Well, it's almost worked, but those BOOST_PP_TUPLE_EAT_2's should expand to nothing. I guess it needs another expansion. The following might work. Please can you try it out?
results in attachment.
In practice these macros will only get called from the other boost macros which might cause these macros to expand fully? Paul will understand this a lot better than me.
#include <boost/preprocessor/detail/split.hpp> #include <boost/preprocessor/punctuation/comma.hpp> #include <boost/preprocessor/punctuation/paren.hpp> #include <boost/preprocessor/tuple/eat.hpp>
#define IS_NULLARY(x) \ IS_NULLARY_2(BOOST_PP_SPLIT(1, IS_NULLARY_C x BOOST_PP_COMMA() 0)) \ /**/ #define IS_NULLARY_2(x) x #define IS_NULLARY_C() \ ~, 1 BOOST_PP_RPAREN() \ BOOST_PP_TUPLE_EAT(2) BOOST_PP_LPAREN() ~ \ /**/
IS_NULLARY(()) // 1 IS_NULLARY(()abc) // 1 IS_NULLARY(+) // 0 IS_NULLARY(xyz) // 0
#define IS_UNARY(x) IS_NULLARY(IS_UNARY_C x) #define IS_UNARY_C(a) ()
IS_UNARY((a)) // 1 IS_UNARY((a)abc) // 1 IS_UNARY(+) // 0 IS_UNARY(xyz) // 0
_______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
#line 15 "pp.cpp" 1 BOOST_PP_TUPLE_EAT_2 ( ~ , 0) 1 BOOST_PP_TUPLE_EAT_2 ( ~abc , 0) 0 0 #line 23 1 BOOST_PP_TUPLE_EAT_2 ( ~ , 0) 1 BOOST_PP_TUPLE_EAT_2 ( ~abc , 0) 0 0