boost::combine, range-based for and structured bindings
The real answer is to use either boost::tie
or grab the range-v3 zip()
which actually yields a std::tuple
.
The for educational purposes only answer is just to adapt the structured bindings machinery for boost::tuples::cons
. That type already has a get()
which works with ADL and does the right thing, so all we need to do is provide tuple_size
and tuple_element
(which ends up being really easy to do since these exact traits already exist in Boost):
namespace std {
template <typename T, typename U>
struct tuple_size<boost::tuples::cons<T, U>>
: boost::tuples::length<boost::tuples::cons<T, U>>
{ };
template <size_t I, typename T, typename U>
struct tuple_element<I, boost::tuples::cons<T, U>>
: boost::tuples::element<I, boost::tuples::cons<T, U>>
{ };
}
But don't actually do that in real code, since really only the type author should opt-in to this kind of thing.
That'll make the structured binding just work.