Re: [Boost-users] mpl::transform<...> --- compile error: is not derived from type

7 Sep 2008


      e r wrote:
...
e r wrote:
...
hi,
here's the problem i have:
    struct my{
      template<typename UInt>
      struct apply{
           typedef mpl::int_UInt::value type;
      };
   };
template
    struct id_range{
        typedef mpl::transform<
            mpl::range_c
            , my
            , mpl::back_inserter< mpl::vector<> >
        >::type type;
/home/er/cpp/boost/random/mcmc/id_range.hpp|32|error: type
‘boost::mpl::transform,
boost::random::mcmc::<unnamed>::my,
boost::mpl::back_inserter >, mpl_::na>’ is not derived
from type ‘boost::random::mcmc::id_range’|
however, for example, this --instead-- compiles fine:
struct id_range{
        typedef mpl::transform<
            mpl::range_c
            , my
            , mpl::back_inserter< mpl::vector<> >
        >::type type;
 };
any suggestion appreciated. thanks!
and also, although the second version compiles, i have
BOOST_MPL_ASSERT( (
            is_same<
                id_range::type,
                mpl::vector< mpl::int_<1>, mpl::int_<2>, mpl::int_<3> >
            >
    ) );
causes,
error: no matching function for call to
‘assertion_failed(mpl_::failed************
boost::is_same,
boost::mpl::v_item, boost::mpl::vector, 0>, 0>,
boost::mpl::vector, mpl_::int_<2>, mpl_::int_<3>,
mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na,
mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na,
mpl_::na, mpl_::na, mpl_::na> >::************)’|
In the first post: there's a typename missing, which solves the problem.