er wrote: I would have
thought that this is feasible because accumulator_set initializes (a) before (b), but apparently b.x_ is initialized with a garbage value.
Still trying to figure it out ... Also did the following check (OK) : typedef set_type::accumulators_mpl_vector::type wrapped_features; typedef mpl::transform< wrapped_features, accumulators::detail::feature_tag<mpl::_1>
::type features;
BOOST_STATIC_ASSERT(( mpl::equal_to< mpl::size_t<2>, mpl::size<features>::type >::value )); //OK typedef mpl::back<features>::type actual_back; BOOST_STATIC_ASSERT(( is_same<b_type,actual_back>::value )); //OK