CPP-TemplateMetaprog/exercise-3-4_8hpp_source.html

// ===-- chapter-3/exercise-3-4.hpp ----------------------- -*- C++ -*- --=== //

#ifndef EXERCISE_3_4

#define EXERCISE_3_4


#include "chapter-3-twice.hpp"


#include <boost/static_assert.hpp>


#include <boost/type_traits/add_pointer.hpp>


#include <boost/mpl/equal.hpp>

#include <boost/mpl/placeholders.hpp>

using namespace boost::mpl::placeholders;


namespace exercise_3_4 {

using namespace chapter3;


typedef twice<

    boost::add_pointer<_1>,

    twice< boost::add_pointer<_1>, int >::type

>::type double_twice;


BOOST_STATIC_ASSERT((

    boost::mpl::equal< double_twice, int**** >::type::value));


} // namespace exercise_3_4


#endif // EXERCISE_3_4

chapter-3-twice.hpp
Define the twice metafunction for use in multiple exercises.

chapter3
Provide utilities availble to all Chapter 3 solutions.
Definition: chapter-3-twice.hpp:17

exercise_3_4
Encapsulate solution for Exercise 3-4.
Definition: exercise-3-4.hpp:35

exercise_3_4::BOOST_STATIC_ASSERT
BOOST_STATIC_ASSERT((boost::mpl::equal< double_twice, int **** >::type::value))

exercise_3_4::double_twice
twice< boost::add_pointer< _1 >, twice< boost::add_pointer< _1 >, int >::type >::type double_twice
Call twice on itself to add four pointers to a type.
Definition: exercise-3-4.hpp:42

chapter3::twice
Apply a metafunction to its own result.
Definition: chapter-3-twice.hpp:28