Re: [Boost-users] [multi_index] using boost::tuple and hash_unique

From: Ovanes Markarian (om_boost_at_[hidden])
Date: 2007-04-23 14:08:31

On Mon, April 23, 2007 19:34, Joaquín Mª López Muñoz wrote:

>
> I don't know what the problem is but it looks like there's more to it
> than you described. Please see the attached compilable snippet mimicking
> your scenario: it works OK for GCC 3.2, and it uses the string const&
> version of create_type(). Do you observe otherwise? When you say that
> the former fails: do you mean you get a compiler error? If so, what's
> it like?

Well, what I mean is the following sample:

#include <boost/array.hpp>

#include <boost/multi_index_container.hpp>
#include <boost/multi_index/hashed_index.hpp>
#include <boost/multi_index/member.hpp>
#include <utility>
#include <string>
#include <iostream>

namespace mi=boost::multi_index;

typedef int some_type;

typedef std::pair<std::string, some_type const*> key_value_pair;

//actually this is a predefined type
boost::array<key_value_pair, 5>   predefined_types =
{
        key_value_pair("test1", NULL)
,	key_value_pair("test2", NULL)
,	key_value_pair("test3", NULL)
,	key_value_pair("test4", NULL)
,	key_value_pair("test5", NULL)
};

struct hash{}; //tag used to retrieve values

typedef mi::multi_index_container
<
  key_value_pair,
  mi::indexed_by
  <
    mi::hashed_unique
    <
      mi::tag<hash>,
      BOOST_MULTI_INDEX_MEMBER(key_value_pair, std::string, first)
    >
  >
> types_map;

types_map types_(predefined_types.begin(), predefined_types.end());

inline void create_type(std::string const& name)
{
        types_.insert(std::make_pair<std::string, some_type const*>(name, NULL));
}

inline bool has_type(std::string const& name)
{
  types_map::index<hash>::type::const_iterator i=types_.get<hash>().find(name), end =
types_.get<hash>().end();
  return i!=end;
}

int main()
{
        //std::string s("hello");
        //create_type(s);

        std::string s2("test3");
        std::cout << "multi_index instance contains string \""+s2+"\": " << (has_type(s2)?"yes":"no");
}

But in a clean environment it works fine and 'has_type' finds the string. May be I have some
globally available identifier, which returns the wrong string, and therefore fails... I will
double check it and get back to this post if I identify smth. Many thanks for your great support!

With Kind Regards,

Ovanes Markarian