at

Boost C++ Libraries

at

Description

Returns the result type of at ^[6] .

Synopsis

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`	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>

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

Copyright © 2001-2007 Joel de Guzman, Dan Marsden, Tobias Schwinger