The BOOST_PP_LIST_FIRST_N macro expands to a list of the first count elements of a list.
Usage
BOOST_PP_LIST_FIRST_N(count, list)
Arguments
- count
-
The number of elements to extract.
- list
-
The list from which the elements are extracted.
Remarks
This macro extracts count elements from the beginning of list and returns them as a list
Previously, this macro could not be used inside BOOST_PP_WHILE.
There is no longer any such restriction.
It is more efficient, however, to use BOOST_PP_LIST_FIRST_N_D in such a situation.
See Also
Requirements
#include <boost/preprocessor/list/first_n.hpp>
#define LIST (a, (b, (c, BOOST_PP_NIL)))
BOOST_PP_LIST_FIRST_N(2, LIST) // expands to (a, (b, BOOST_PP_NIL))