...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Returns the result type of at
[6].
template< typename Seq, typename N> struct at { typedef unspecified type; };
Table 1.29. Parameters
Parameter |
Requirement |
Description |
---|---|---|
|
A model of Random Access Sequence |
Argument sequence |
|
Index of element |
result_of::at<Seq, N>::type
Return type: Any type.
Semantics: Returns the result type of
using at
to access the N
th element of Seq
.
#include <boost/fusion/sequence/intrinsic/at.hpp> #include <boost/fusion/include/at.hpp>
typedefvector
<int,float,char> vec; BOOST_MPL_ASSERT((boost::is_same<result_of::at
<vec, boost::mpl::int_<1> >::type, float&>));
[6]
result_of::at
reflects the actual return
type of the function at
. Sequence(s)
typically return references to its elements via the at
function. If you want to
get the actual element type, use result_of::value_at