BOOST_PP_FILENAME

The BOOST_PP_FILENAME_x macro is a user-defined named external argument used by BOOST_PP_ITERATE. It denotes the file to be iterated over.

#define BOOST_PP_FILENAME_x filename

x: The iteration depth of the next file-iteration. This value must be the current iteration depth + 1.
filename: A quoted or angle-bracketed filename to used as the target of a file-iteration.

This macro is part of the secondary method of passing arguments to BOOST_PP_ITERATE. The other part is BOOST_PP_ITERATION_LIMITS.

This macro is automatically undefined for reuse by a call to BOOST_PP_ITERATE.