Re: [Boost-users] multi-inheritance from elements of mpl::vector? ==> inherit_scattered ( for Barton & Nackmann trick)

From: Oliver.Kowalke_at_[hidden]
Date: 2005-10-27 07:01:46

no reply - so I found a solution by myself (used for the Barton &
Nackmann trick)!
cu,
Oliver

Code:

#include <iostream>
#include <cstdlib>
#include <string>

#include <boost/mpl/begin_end.hpp>
#include <boost/mpl/deref.hpp>
#include <boost/mpl/next.hpp>
#include <boost/mpl/vector.hpp>

namespace mpl = boost::mpl;

////////////////////////////////////

template< 
        typename B,
        typename E
>
struct scattered;

template< 
        typename B,
        typename E
>
struct scattered
:
public mpl::deref< B >::type,
public scattered< 
                        typename mpl::next< B >::type, 
                        E 
		>
{};

template< typename E >
struct scattered< E, E >
{};

////////////////////////////////////

template< typename Sequence >
struct inherit_scattered
: 
public scattered< 
                        typename mpl::begin< Sequence >::type, 
                        typename mpl::end< Sequence >::type 
		>
{};

////////////////////////////////////

template< typename D >
struct F
{
        std::string f()
        { return static_cast< D & >( * this).str_; }
};

template< typename D >
struct G
{
        std::string g()
        { return static_cast< D & >( * this).str_; }
};

////////////////////////////////////

class A
: 
public inherit_scattered< 
                        mpl::vector< 
                                F< A >,
                                G< A >
			> 
		>
{
private:
        template< typename X >
        friend struct F;

        template< typename X >
        friend struct G;

        std::string	str_;

public:
        A( std::string const& str)
        : str_( str)
        {}
};

int main( int argc, char *argv[])
{
        A a("Hello World!");
        std::cout << a.f() << std::endl;
        std::cout << a.g() << std::endl;
        return EXIT_SUCCESS;
}

>Hi,
>how is it possible to inherit from all items inside mpl::vector?
>
>template< typename V >
>class multi
>: .... // ?????
>{};
>
>typedef multi < mpl::vector< A ,B, C > > multi _t;
>multi_t m; // m has all public and protected member functions of A, B
and C

>Best Regards,
>Oliver