On 5/21/2010 3:20 AM, Adam Badura wrote:
BOOST_PP_SEQ_FOR_EACH macro when used within another BOOST_PP_SEQ_FOR_EACH does not expand at all (and the same happens with _R versions). I use Visual Studio 2005.
Yes, I've run into this problem, too. It occurs with some of the *_R, *_S, etc. Boost.PP macros when the "macro" argument (perhaps indirectly) contains the same Boost.PP macro. The workaround I've been using is to create variants which actually accept the "r" parameter as a concatenation, to avoid nested calls to the same macro: #define BOOST_EXT_PP_SEQ_FOR_EACH_0_for_macro( r, state ) BOOST_PP_TUPLE_ELEM( 4, 1, state ) ( r, BOOST_PP_TUPLE_ELEM( 4, 2, state ), BOOST_PP_SEQ_HEAD( BOOST_PP_TUPLE_ELEM( 4, 3, state ) ) ) #define BOOST_EXT_PP_SEQ_FOR_EACH_1_for_macro( r, state ) BOOST_PP_TUPLE_ELEM( 4, 1, state ) ( r, BOOST_PP_TUPLE_ELEM( 4, 2, state ), BOOST_PP_SEQ_HEAD( BOOST_PP_TUPLE_ELEM( 4, 3, state ) ) ) #define BOOST_EXT_PP_SEQ_FOR_EACH_2_for_macro( r, state ) BOOST_PP_TUPLE_ELEM( 4, 1, state ) ( r, BOOST_PP_TUPLE_ELEM( 4, 2, state ), BOOST_PP_SEQ_HEAD( BOOST_PP_TUPLE_ELEM( 4, 3, state ) ) ) ... #define BOOST_EXT_PP_SEQ_FOR_EACH_0( macro, data, seq ) BOOST_PP_FOR_0( ( BOOST_PP_SEQ_SIZE( seq ), macro, data, seq ), BOOST_EXT_PP_SEQ_FOR_EACH_for_pred, BOOST_EXT_PP_SEQ_FOR_EACH_for_op, BOOST_EXT_PP_SEQ_FOR_EACH_0_for_macro ) #define BOOST_EXT_PP_SEQ_FOR_EACH_1( macro, data, seq ) BOOST_PP_FOR_1( ( BOOST_PP_SEQ_SIZE( seq ), macro, data, seq ), BOOST_EXT_PP_SEQ_FOR_EACH_for_pred, BOOST_EXT_PP_SEQ_FOR_EACH_for_op, BOOST_EXT_PP_SEQ_FOR_EACH_1_for_macro ) #define BOOST_EXT_PP_SEQ_FOR_EACH_2( macro, data, seq ) BOOST_PP_FOR_2( ( BOOST_PP_SEQ_SIZE( seq ), macro, data, seq ), BOOST_EXT_PP_SEQ_FOR_EACH_for_pred, BOOST_EXT_PP_SEQ_FOR_EACH_for_op, BOOST_EXT_PP_SEQ_FOR_EACH_2_for_macro ) ... and so on (generated with a script), with #define BOOST_EXT_PP_SEQ_FOR_EACH_for_pred( r, state ) \ BOOST_PP_TUPLE_ELEM( 4, 0, state ) #define BOOST_EXT_PP_SEQ_FOR_EACH_for_op( r, state ) \ ( \ BOOST_PP_DEC( BOOST_PP_TUPLE_ELEM( 4, 0, state ) ), \ BOOST_PP_TUPLE_ELEM( 4, 1, state ), \ BOOST_PP_TUPLE_ELEM( 4, 2, state ), \ BOOST_PP_SEQ_TAIL( BOOST_PP_TUPLE_ELEM( 4, 3, state ) ) \ ) I don't know if this is the optimal solution, but it's worked fine for me. I have a similar thing built for SEQ_TRANSFORM[_S]. - Jeff