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Returns the actual element type associated with a Key from the Sequence.
template< typename Seq, typename Key> struct value_at_key { typedef unspecified type; };
Table 1.34. Parameters
| Parameter | Requirement | Description | 
|---|---|---|
| 
                       | A model of Associative Sequence | Argument sequence | 
| 
                       | Any type | Key type | 
result_of::value_at_key<Seq, Key>::type
Return type: Any type.
            Precondition: has_key<Seq, Key>::type::value == true
            (where Seq is not Unbounded Sequence)
          
            Semantics: Returns the actual element
            type associated with key type Key
            in Seq.
          
#include <boost/fusion/sequence/intrinsic/value_at_key.hpp> #include <boost/fusion/include/value_at_key.hpp>
typedefmap<pair<int, char>,pair<char, char>,pair<double, char> > mymap; BOOST_MPL_ASSERT((boost::is_same<result_of::value_at_key<mymap, int>::type, char>));