Hi all,
[added this line to make gmane happy.]
I'm looking for a way to remove "empty" values from a tuple. In other words, say I have a tuple T: tuple<E, int, E, double, E, char, E> T; // where E can be either null_type, or mpl::void_, etc. I'd like for it to collapse into: tuple<int, double, char> T2; Now, the reason I say "values" is because I found a way to do just that, but only for the types, which you'll find below. However, I can't figure out how to then *construct* the collapsed tuple given the original tuple (and its values.) Specifically, it's the `???' below that I'm missing. Thanks! // Collapse code: template <typename Sequence> struct tuple_from_sequence : mpl::reverse_fold < Sequence , tuples::null_type , tuples::cons<mpl::_2, mpl::_1> > {}; template <typename T0, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7, typename T8, typename T9> struct collapse <tuple<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9> > { typedef tuple<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9> original; typedef mpl::list<T0, T1, T2, T3, T4, T5, T6, T7, T8, T9> sequence; typedef typename mpl::remove<sequence, tuples::null_type>::type removed; typedef typename tuple_from_sequence<removed>::type type; static type construct(original const& t) { // return ???; } };