Boost C++ Libraries

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Struct template valid_member_metafunction

boost::tti::valid_member_metafunction — A metafunction which checks whether the invoked macro metafunction generated by BOOST_TTI_MEMBER_TYPE ( BOOST_TTI_TRAIT_MEMBER_TYPE ) hold a valid type.

Synopsis

// In header: <boost/tti/member_type.hpp>

template<typename BOOST_TTI_METAFUNCTION> 
struct valid_member_metafunction : public boost::mpl::not_< boost::is_same< BOOST_TTI_METAFUNCTION::type, BOOST_TTI_METAFUNCTION::boost_tti_marker_type > >
{
};

Description

The metafunction 'valid_member_metafunction', which is in the boost::tti namespace, takes the form of:

template<class BOOST_TTI_METAFUNCTION>
struct valid_member_metafunction
  {
  static const value = unspecified;
  typedef mpl::bool_<true-or-false> type;
  };

The metafunction types and return:

  BOOST_TTI_METAFUNCTION = The invoked macro metafunction generated by BOOST_TTI_MEMBER_TYPE ( BOOST_TTI_TRAIT_MEMBER_TYPE ).

  returns          = 'value' is true if the nested type of the invoked metafunction is valid, otherwise 'value' is false.
                     A valid type means that the invoked metafunction's inner 'type' is not the marker type.