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Class template apply_visitor_delayed_t

boost::apply_visitor_delayed_t — Adapts a visitor for use as a function object.


// In header: <boost/variant/apply_visitor.hpp>

template<typename Visitor> 
class apply_visitor_delayed_t {
  // types
  typedef typename Visitor::result_type result_type;

  // construct/copy/destruct
  explicit apply_visitor_delayed_t(Visitor &);

  // function object interface
  template<typename ... Variant> result_type operator()(Variant&...);
  template<typename Variant> result_type operator()(Variant &);
  template<typename Variant1, typename Variant2> 
    result_type operator()(Variant1 &, Variant2 &);


Adapts the function given at construction for use as a function object. This is useful, for example, when one needs to operate on each element of a sequence of variant objects using a standard library algorithm such as std::for_each.

See the "visitor-only" form of apply_visitor for a simple way to create apply_visitor_delayed_t objects.

See apply_visitor_delayed_cpp14_t which is used on C++14 compatible compilers when Visitor has no result_type typedef.

apply_visitor_delayed_t public construct/copy/destruct

  1. explicit apply_visitor_delayed_t(Visitor & visitor);


    Constructs the function object with the given visitor.

apply_visitor_delayed_t function object interface

  1. template<typename ... Variant> result_type operator()(Variant&... operand);
    template<typename Variant> result_type operator()(Variant & operand);
    template<typename Variant1, typename Variant2> 
      result_type operator()(Variant1 & operand1, Variant2 & operand2);
    Function call operator.

    Invokes apply_visitor on the stored visitor using the given operands.


    Version with variadic templates is used by default if BOOST_VARIANT_DO_NOT_USE_VARIADIC_TEMPLATES is not defined.