The BOOST_PP_TUPLE_ELEM macro extracts an element from a tuple.

Usage

BOOST_PP_TUPLE_ELEM(size, i, tuple)

Arguments

size
The size of the tuple.  Valid tuple sizes range from 0 to BOOST_PP_LIMIT_TUPLE. 
i
The zero-based index into the tuple of the element to be extracted.  Valid values range from 0 to size - 1.
tuple
The tuple from which an element is to be extracted.

Remarks

The size argument must be the actual size of the tuple, and i must be less than the size of the tuple.

See Also

Requirements

Header:  <boost/preprocessor/tuple/elem.hpp>

Sample Code

#include <boost/preprocessor/tuple/elem.hpp>

#define TUPLE (a, b, c, d)

BOOST_PP_TUPLE_ELEM(4, 0, TUPLE) // expands to a
BOOST_PP_TUPLE_ELEM(4, 3, TUPLE) // expands to d