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Returns the result type of at [5] .
template< typename Seq, typename N> struct at { typedef unspecified type; };
Table 1.25. Parameters
Parameter |
Requirement |
Description |
---|---|---|
Seq |
A model of Forward Sequence |
Argument sequence |
N |
Index of element |
result_of::at<Seq, N>::type
Return type: Any type.
Semantics: Returns the result type of using at to access the Nth element of Seq.
/sequence/intrinsic/at.hpp>
typedef vector<int,float,char> vec; BOOST_MPL_ASSERT((boost::is_same<result_of::at<vec, boost::mpl::int_<1> >::type, float&>));
[5] 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