Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

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at_c
Description

Returns the result type of at_c [7] .

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

Table 1.30. Parameters

Parameter

Requirement

Description

Seq

A model of Forward Sequence

Argument sequence

M

Positive integer index

Index of element


Expression Semantics
result_of::at_c<Seq, M>::type

Return type: Any type

Semantics: Returns the result type of using at_c to access the Mth 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_c<vec, 1>::type, float&>));


[7] 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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