at_c

template<
    typename Seq,
    int N>
struct at_c
{
    typedef unspecified type;
};

Table 1.29. Parameters

Parameter	Requirement	Description
`Seq`	A model of Random Access Sequence	Argument sequence
`N`	Positive integer index	Index of element

result_of::at_c<Seq, N>::type

Return type: Any type

Precondition: 0 <= N < result_of::size<Seq>::value (where Seq is not Unbounded Sequence)

Semantics: Returns the result type of using at_c to access the Nth element of Seq.

#include <boost/fusion/sequence/intrinsic/at.hpp>
#include <boost/fusion/include/at.hpp>

typedef vector<int,float,char> vec;
BOOST_MPL_ASSERT((boost::is_same<result_of::at_c<vec, 1>::type, float&>));

^[8] result_of::at_c reflects the actual return type of the function at_c. Sequence(s) typically return references to its elements via the at_c function. If you want to get the actual element type, use result_of::value_at_c

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