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Returns the result type of at
[6]
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template< typename Seq, typename N> struct at { typedef unspecified type; };
Table 1.29. Parameters
|
Parameter |
Requirement |
Description |
|---|---|---|
|
|
A model of Forward 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 Nth 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