...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::proto::result_of::unpack_expr — Metafunction that computes the return type of the
proto::unpack_expr()
function, with a domain deduced from the domains of the children.
template<typename Tag, typename Sequence, typename Void = void>
struct unpack_expr {
// types
typedef
typename proto::result_of::make_expr<
Tag,
typename fusion::value_at<Sequence, 0>::type,
...
typename fusion::value_at<Sequence, N
-1>::type
>::type
type; // Where N is the size of Sequence.
};
Compute the return type of the
proto::unpack_expr()
function.
Sequence
is a Fusion Random Access Sequence.
In this specialization, the domain is deduced from the domains of the child types.
If proto::is_domain<Sequence>::value
is true
, then another specialization is selected.