boost::result_of::extract_or_default< T, DefaultT, TagT > Struct Template Reference

A metafunction that allows to acquire the result of the value extraction. More...

#include <value_extraction_fwd.hpp>

Public Types
typedef mpl::eval_if < mpl::is_sequence< T > , mpl::eval_if< mpl::contains < T, DefaultT >, mpl::identity < T >, mpl::push_back< T, DefaultT > >, mpl::if_ < is_same< T, DefaultT >, T, mpl::vector2< T, DefaultT > > >::type	extracted_type
typedef mpl::if_ < mpl::is_sequence < extracted_type >, value_ref < extracted_type, TagT > , extracted_type const & > ::type	type

Detailed Description

template<typename T, typename DefaultT, typename TagT>
struct boost::result_of::extract_or_default< T, DefaultT, TagT >

A metafunction that allows to acquire the result of the value extraction.

The metafunction results in a type that is in form of T const&, if T is not an MPL type sequence and DefaultT is the same as T, or value_ref< TypesT, TagT > otherwise, with TypesT being a type sequence comprising the types from sequence T and DefaultT, if it is not present in T already.

Member Typedef Documentation

template<typename T , typename DefaultT , typename TagT >

typedef mpl::eval_if< mpl::is_sequence< T >, mpl::eval_if< mpl::contains< T, DefaultT >, mpl::identity< T >, mpl::push_back< T, DefaultT > >, mpl::if_< is_same< T, DefaultT >, T, mpl::vector2< T, DefaultT > > >::type boost::result_of::extract_or_default< T, DefaultT, TagT >::extracted_type

template<typename T , typename DefaultT , typename TagT >

typedef mpl::if_< mpl::is_sequence< extracted_type >, value_ref< extracted_type, TagT >, extracted_type const& >::type boost::result_of::extract_or_default< T, DefaultT, TagT >::type

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The documentation for this struct was generated from the following file:

• boost_1_57_0/boost/log/attributes/value_extraction.hpp