"Paul Mensonides" <pmenso57@comcast.net> wrote
This will work on most compilers (including VC)...
#include <boost/preprocessor/control/iif.hpp> #include <boost/preprocessor/detail/is_unary.hpp> #include <boost/preprocessor/repetition/repeat.hpp> #include <boost/preprocessor/tuple/eat.hpp>
#define TRANSLATE(x) \ BOOST_PP_IIF( \ BOOST_PP_IS_UNARY(x), \ x BOOST_PP_TUPLE_EAT(3), BOOST_PP_REPEAT \ )(x, TRANSLATE_2, ~) \ /**/ #define TRANSLATE_2(z, n, _) (class)
TRANSLATE( (class)(unsigned)(bool) ) // --> (class)(unsigned)(bool)
TRANSLATE( 3 ) // --> (class)(class)(class)
This will work on most preprocessors, but not on those that use the Borland configuration. Thanks to Daniel James, I do have a workaround for that bug for Borland in particular, but I don't have verification that it works on other preprocessors that use that configuration (so it has to wait until I can separate the implementations).
This definitely has a benefit of not having to provide multiple defines (but rather rely on ones in the Boost.Preprocessor). However, it uses some internal feature, IS_UNARY, which I guess is not a huge drawback since the suggestion comes from the author :-) The portability issue is somewhat of concern -- I would not like to compromise it because of this nicety feature... Do you think my other suggestion might be more portable? #define TRANSLATE(x) BOOST_PP_SEQ_CAT(\ (STEP3)\ (BOOST_PP_CAT(STEP2, BOOST_PP_EXPAND(STEP1 x))) ) #define STEP1(x) _(x) #define STEP3STEP2_(x) (x) #define STEP2STEP1 #define STEP31 (class) #define STEP32 (class)(class) ... Regards, Arkadiy