[Boost-users] [multi-index] Container of polymorphic pointers

Subject: [Boost-users] [multi-index] Container of polymorphic pointers
From: Daniel Dilts (diltsman_at_[hidden])
Date: 2008-10-29 20:58:52

I'm am using boost::multi_index to hold a set of polymorphic entities.  Due
to efficiency concerns, I have to be able sort the container based on actual
type.  I was planning on sorting based on the return result of typeid.  When
I try this I get errors in <functional>.  I am using VC++ 2005 Standard
Edition SP1.  What am I doing wrong, or, what is a better way of
accomplishing what I am trying to do?

#ifndef ENTITIES_ENTITYCONTAINER_H_
#define ENTITIES_ENTITYCONTAINER_H_

#include <boost/multi_index_container.hpp>
#include <boost/multi_index/ordered_index.hpp>
#include "Entity.h"

namespace Entities
{
    struct type{};
    struct extractType
    {
        typedef const type_info& result_type;

        result_type operator()(const Entity * r)const // operator() must be
const
        {
            return typeid(*r);
        }
    };
    typedef boost::multi_index::multi_index_container<
        Entity *,
        boost::multi_index::indexed_by<

 boost::multi_index::ordered_non_unique<boost::multi_index::tag<type>,
extractType>
        >
    > EntityContainer;
};

#endif