Boost C++ Libraries

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at
Description

Returns the result type of at [6] .

Synopsis
template<
    typename Seq,
    typename N>
struct at
{
    typedef unspecified type;
};

Table 1.29. Parameters

Parameter

Requirement

Description

Seq

A model of Forward Sequence

Argument sequence

N

An MPL Integral Constant

Index of element


Expression Semantics
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.

Header
#include <boost/fusion/sequence/intrinsic/at.hpp>
#include <boost/fusion/include/at.hpp>
Example
typedef vector<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


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