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Using Interfaces for Object Oriented Primitives

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7 Dec 20047 min read 57.4K   369   27  
An introduction to the OOTL (Object Oriented Template Library). Describes how the OOTL uses a bleeding-edge technique of defining interface types in C++ to provide lightweight object-oriented primitives with run-time polymorphism through an IObject interface.
 
// (C) Copyright Jonathan Turkanis 2004.
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)

// Disclaimer: Not a Boost library.

#ifndef BOOST_IDL_SUBINTERFACE_HPP_INCLUDED
#define BOOST_IDL_SUBINTERFACE_HPP_INCLUDED

#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif

#include <boost/interfaces/access.hpp>
#include <boost/interfaces/detail/flags.hpp>
#include <boost/interfaces/detail/generate.hpp>
#include <boost/interfaces/detail/macros/template_decl.hpp>
#include <boost/interfaces/detail/macros/template_args.hpp>
#include <boost/interfaces/interface_fwd.hpp>
#include <boost/mpl/at.hpp>
#include <boost/mpl/aux_/na.hpp>
#include <boost/mpl/fold.hpp>
#include <boost/mpl/identity.hpp>
#include <boost/mpl/list.hpp>
#include <boost/mpl/range_c.hpp>
#include <boost/mpl/size.hpp>
#include <boost/mpl/transform_view.hpp>
#include <boost/preprocessor/control/expr_if.hpp>
#include <boost/preprocessor/punctuation/comma_if.hpp>
#include <boost/preprocessor/repetition/enum_params.hpp>

namespace boost { namespace interfaces {       

//------------------Definition of helper templates----------------------------//   

namespace detail {

template<typename Subinterface, typename Superinterfaces>
struct subinterface_traits {
    template< typename Derived, 
              typename Flags = flags::default_, 
              typename Base = detail::empty_base >
    struct generator_impl {
        struct get_generator {
            template<typename Interface>
            struct apply {
                typedef typename Interface::template
                        generator<Derived, Flags, Base> type;
            };
        };
        typedef typename
                mpl::transform_view<
                    Superinterfaces, 
                    get_generator
                >::type                         generators;           
        typedef typename
                mpl::fold<
                    generators, 
                    empty_base, 
                    generate
                >::type                         type;
        typedef typename type::interface_table  interface_table;
    };
      
    template< typename Derived, 
              typename Flags = flags::default_, 
              typename Base = detail::empty_base >
    struct generator 
        : generator_impl<Derived, Flags, Base>::type 
    { };

    struct type : generator<Subinterface> { 
        template< typename Derived, 
                  typename Flags = flags::default_, 
                  typename Base = detail::empty_base >
        struct generator 
            : subinterface_traits<Subinterface, Superinterfaces>
                   ::template generator<Derived, Flags, Base>
            { };
    };
};

} // End namespace detail.

//------------------Definition of class template subinterface-----------------//

template<typename Subinterface, typename Superinterfaces>
class subinterface 
    : public detail::subinterface_traits<
                 Subinterface, Superinterfaces
             >::type        
{
private:
    friend class interface_core_access;
    typedef typename 
            detail::subinterface_traits<
                 Subinterface, Superinterfaces
             >::type                              base_type;
protected:
    typedef subinterface                          subinterface_;
public:
    typedef Superinterfaces                       superinterfaces;
    typedef typename base_type::interface_table   interface_table; 
};

//------------------Definition of subinterface macros-------------------------//

#define BOOST_SUBINTERFACE_BEGIN(name) \
    struct BOOST_PP_CAT(name, _subinterface_impl_) \
        : ::boost::mpl::identity< ::boost::mpl::list< \
    /**/

#define BOOST_SUBINTERFACE_TEMPLATE_BEGIN(name, arity) \
    BOOST_SUBINTERFACE_BEGIN(name) \
    /**/

#define BOOST_SUPERINTERFACE(name) name, 

#define BOOST_SUBINTERFACE_END_IMPL(name, arity) ::boost::mpl::na> > { }; \
    BOOST_IDL_TEMPLATE_DECL(arity, XXX_) \
    struct name : ::boost::interfaces::subinterface< \
                      name BOOST_IDL_TEMPLATE_ARGS(arity, XXX_), \
                      BOOST_PP_EXPR_IF(arity, typename) \
                          BOOST_PP_CAT(name, _subinterface_impl_) \
                          BOOST_IDL_TEMPLATE_ARGS(arity, XXX_)::type \
                  > \
    { \
        friend class ::boost::interfaces::access; \
        typedef BOOST_PP_EXPR_IF(arity, typename) \
                ::boost::interfaces::subinterface< \
                      name BOOST_IDL_TEMPLATE_ARGS(arity, XXX_), \
                      BOOST_PP_EXPR_IF(arity, typename) \
                          BOOST_PP_CAT(name, _subinterface_impl_) \
                          BOOST_IDL_TEMPLATE_ARGS(arity, XXX_)::type \
                > base_type; \
        typedef BOOST_PP_EXPR_IF(arity, typename) \
                base_type::interface_table interface_table; \
        template<typename XXX_> \
        struct interface_functions \
            : base_type::template interface_functions<XXX_>, \
             ::boost::interfaces::detail::table_holder<interface_table, XXX_> \
        { \
            using ::boost::interfaces::detail \
                  ::table_holder<interface_table, XXX_>::m_table_; \
        }; \
        BOOST_IDL_CTORS(name, XXX_) \
        BOOST_IDL_CORE_INTERFACE_SUPPORT(name) \
    }; \
    template< typename XXX_ BOOST_PP_COMMA_IF(arity) \
              BOOST_PP_ENUM_PARAMS(arity, typename YYY_) > \
    ::boost::type_traits::yes_type \
    is_interface_helper( name BOOST_IDL_TEMPLATE_ARGS(arity, YYY_)*, \
                         XXX_*, \
                         typename \
                         ::boost::interfaces::detail::enable_if_same< \
                            XXX_, \
                            name BOOST_IDL_TEMPLATE_ARGS(arity, YYY_) \
                         >::type* = 0 ); \
    /**/

#define BOOST_SUBINTERFACE_END(name) BOOST_SUBINTERFACE_END_IMPL(name, 0) 

#define BOOST_SUBINTERFACE_TEMPLATE_END(name, arity) \
    BOOST_SUBINTERFACE_END_IMPL(name, arity) \
    /**/

} } // End namespaces interfaces, boost.

#endif // #ifndef BOOST_IDL_SUBINTERFACE_HPP_INCLUDED

//// (C) Copyright Jonathan Turkanis 2004.
//// Distributed under the Boost Software License, Version 1.0. (See accompanying
//// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
//
//// Disclaimer: Not a Boost library.
//
//#ifndef BOOST_IDL_SUBINTERFACE_HPP_INCLUDED
//#define BOOST_IDL_SUBINTERFACE_HPP_INCLUDED
//
//#if defined(_MSC_VER) && (_MSC_VER >= 1020)
//# pragma once
//#endif
//
//#include <boost/interfaces/access.hpp>
//#include <boost/interfaces/detail/flags.hpp>
//#include <boost/interfaces/detail/generate.hpp>
//#include <boost/interfaces/detail/template_params.hpp>
//#include <boost/interfaces/interface_fwd.hpp>
//#include <boost/mpl/at.hpp>
//#include <boost/mpl/aux_/na.hpp>
//#include <boost/mpl/fold.hpp>
//#include <boost/mpl/identity.hpp>
//#include <boost/mpl/list.hpp>
//#include <boost/mpl/range_c.hpp>
//#include <boost/mpl/size.hpp>
//#include <boost/mpl/transform_view.hpp>
//#include <boost/preprocessor/control/expr_if.hpp>
//#include <boost/preprocessor/punctuation/comma_if.hpp>
//#include <boost/preprocessor/repetition/enum_params.hpp>
//
//namespace boost { namespace interfaces {       
//
////------------------Definition of helper templates----------------------------//   
//
//namespace detail {
//
//template<typename Subinterface, typename Superinterfaces>
//struct subinterface_traits {
//    template< typename Derived, 
//              typename Flags = flags::default_, 
//              typename Base = detail::empty_base >
//    struct generator_impl {
//        struct get_generator {
//            template<typename Interface>
//            struct apply {
//                typedef typename Interface::template
//                        generator<Derived, Flags, Base> type;
//            };
//        };
//        typedef typename
//                mpl::transform_view<
//                    Superinterfaces, 
//                    get_generator
//                >::type                         generators;           
//        typedef typename
//                mpl::fold<
//                    generators, 
//                    empty_base, 
//                    generate
//                >::type                         type;
//        typedef typename type::interface_table  interface_table;
//    };
//      
//    template< typename Derived, 
//              typename Flags = flags::default_, 
//              typename Base = detail::empty_base >
//    struct generator 
//        : generator_impl<Derived, Flags, Base>::type 
//    { };
//
//    struct type : generator<Subinterface> { 
//        template< typename Derived, 
//                  typename Flags = flags::default_, 
//                  typename Base = detail::empty_base >
//        struct generator 
//            : subinterface_traits<Subinterface, Superinterfaces>
//                   ::template generator<Derived, Flags, Base>
//            { };
//    };
//};
//
//} // End namespace detail.
//
////------------------Definition of class template subinterface-----------------//
//
//template<typename Subinterface, typename Superinterfaces>
//class subinterface 
//    : public detail::subinterface_traits<
//                 Subinterface, Superinterfaces
//             >::type        
//{
//private:
//    friend class interface_core_access;
//    typedef typename 
//            detail::subinterface_traits<
//                 Subinterface, Superinterfaces
//             >::type                              base_type;
//protected:
//    typedef subinterface                          subinterface_;
//public:
//    typedef Superinterfaces                       superinterfaces;
//    typedef typename base_type::interface_table   interface_table; 
//};
//
////------------------Definition of subinterface macros-------------------------//
//
//#define BOOST_SUBINTERFACE_BEGIN(name) \
//    struct BOOST_PP_CAT(name, _subinterface_impl_) \
//        : ::boost::mpl::identity< ::boost::mpl::list< \
//    /**/
//
//#define BOOST_SUBINTERFACE_TEMPLATE_BEGIN(name, arity) \
//    BOOST_SUBINTERFACE_BEGIN(name) \
//    /**/
//
//#define BOOST_SUPERINTERFACE(name) name, 
//
//#define BOOST_SUBINTERFACE_END_IMPL(name, arity) ::boost::mpl::na> > { }; \
//    BOOST_IDL_TEMPLATE_DECL(arity, XXX_) \
//    struct name : ::boost::interfaces::subinterface< \
//                      name BOOST_IDL_TEMPLATE_ARGS(arity, XXX_), \
//                      BOOST_PP_EXPR_IF(arity, typename) \
//                          BOOST_PP_CAT(name, _subinterface_impl_) \
//                          BOOST_IDL_TEMPLATE_ARGS(arity, XXX_)::type \
//                  > \
//    { \
//        friend class ::boost::interfaces::access; \
//        typedef BOOST_PP_EXPR_IF(arity, typename) \
//                ::boost::interfaces::subinterface< \
//                      name BOOST_IDL_TEMPLATE_ARGS(arity, XXX_), \
//                      BOOST_PP_EXPR_IF(arity, typename) \
//                          BOOST_PP_CAT(name, _subinterface_impl_) \
//                          BOOST_IDL_TEMPLATE_ARGS(arity, XXX_)::type \
//                > base_type; \
//        typedef BOOST_PP_EXPR_IF(arity, typename) \
//                base_type::interface_table interface_table; \
//        template<typename XXX_> \
//        struct interface_functions \
//            : base_type::template interface_functions<XXX_> \
//        { static const interface_table m_table_; }; \
//        BOOST_IDL_CTORS(name, XXX_) \
//        BOOST_IDL_CORE_INTERFACE_SUPPORT(name) \
//    }; \
//    BOOST_IDL_TEMPLATE_DECL(arity, XXX_) \
//    template<typename XXX_> \
//    const BOOST_PP_EXPR_IF(arity, typename) name \
//        BOOST_IDL_TEMPLATE_ARGS(arity, XXX_)::interface_table \
//        name BOOST_IDL_TEMPLATE_ARGS(arity, XXX_)::template  \
//            interface_functions<XXX_>::m_table_ = \
//                ::boost::mpl::identity<XXX_>(); \
//    template< typename XXX_ BOOST_PP_COMMA_IF(arity) \
//              BOOST_PP_ENUM_PARAMS(arity, typename YYY_) > \
//    ::boost::type_traits::yes_type \
//    is_interface_helper( name BOOST_IDL_TEMPLATE_ARGS(arity, YYY_)*, \
//                         XXX_*, \
//                         typename \
//                         ::boost::interfaces::detail::enable_if_same< \
//                            XXX_, \
//                            name BOOST_IDL_TEMPLATE_ARGS(arity, YYY_) \
//                         >::type* = 0 ); \
//    /**/
//
//#define BOOST_SUBINTERFACE_END(name) BOOST_SUBINTERFACE_END_IMPL(name, 0) 
//
//#define BOOST_SUBINTERFACE_TEMPLATE_END(name, arity) \
//    BOOST_SUBINTERFACE_END_IMPL(name, arity) \
//    /**/
//
//} } // End namespaces interfaces, boost.
//
//#endif // #ifndef BOOST_IDL_SUBINTERFACE_HPP_INCLUDED

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Written By
Christopher Diggins
Software Developer Ara 3D
Canada Canada
I am the designer of the Plato programming language and I am the founder of Ara 3D. I can be reached via email at cdiggins@gmail.com

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Posted 28 Nov 2004

Article Copyright 2004 by Christopher Diggins
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