I'd like to copy the contents of a boost::mpl::vector_c (or similar) into an output iterator at runtime.
Thank you for the help Rutger, Kim, and Steven, and especially for the mpl::for_each examples and the copy functor. The more complete use case was to turn an MPL sequence into a form usable within an initialization list for either boost::array or something requiring an iterator. For completeness, the helper class I finally went with is below. I appreciate your expertise, Rhys #define BOOST_TEST_MODULE $Id: test_mpl.cc 999 2010-03-18 15:08:46Z rhys $ #include <boost/array.hpp> #include <boost/mpl/vector_c.hpp> #include <boost/mpl/for_each.hpp> #include <boost/mpl/size.hpp> #include <boost/test/included/unit_test.hpp> template< typename Sequence > class sequence_array : public boost::array< typename Sequence::value_type, boost::mpl::size<Sequence>::type::value > { typedef typename boost::array< typename Sequence::value_type, boost::mpl::size<Sequence>::type::value >::iterator iterator; struct copier_ { copier_(iterator it) : it_(it) {} template<typename U> void operator()(U u) { *(it_++) = u; } iterator it_; }; public: sequence_array() { boost::mpl::for_each<Sequence>(copier_(this->begin())); } }; BOOST_AUTO_TEST_CASE( testing ) { sequence_array< boost::mpl::vector_c<int,2,4,6> > a; BOOST_CHECK_EQUAL(a[0], 2); BOOST_CHECK_EQUAL(a[1], 4); BOOST_CHECK_EQUAL(a[2], 6); boost::array<int, 3> b = { 2, 4, 6 }; BOOST_CHECK( b == a ); BOOST_CHECK( a == b ); }