[Boost-users] [bind] static array vs. pointer vector

From: Christian Henning (chhenning_at_[hidden])
Date: 2007-03-26 11:24:08

Hi there, I have posted this question last Friday, already. But maybe
my example was too confusing. Here is a more simple example.
Basically, I don't see what the big difference is when using
boost::bind with a pointer vector ( std::vector<info*> ) and a static
array of info.

Please consider the following code:

#include <string>
#include <algorithm>
#include <functional>
#include <vector>

#include <boost/bind.hpp>

using namespace std;
using namespace boost;

struct info
{
   int    a;
   string s;
};

static info table[] =
{
   { 16, "Hello" },
   { 18, "Moin" }
};

string& get_s( info* p )
{
   return p->s;
}

int _tmain(int argc, _TCHAR* argv[])
{
   {
      vector<info*> v;
      find_if( v.begin(), v.end()
              , bind( equal_to<string>()
                    , bind( &get_s, _1 )
                    , "Moin" ));
   }

   {
      find_if( &table[0], &table[0] + 2
             , bind( equal_to<string>()
                   , bind( &get_s, _1 )
                   , "Moin" ));

   }
}

The second find_if wont complie using MSVC 7.1. The errors are:

c:\boost\boost\bind.hpp(219) : error C2664: 'std::string &(info *)' :
cannot convert parameter 1 from 'info' to 'info *'
        No user-defined-conversion operator available that can perform
this conversion, or the operator cannot be called
        c:\boost\boost\bind\bind_template.hpp(139) : see reference to
function template instantiation 'R boost::_bi::list1<A1>::operator
()<boost::_bi::bind_t<R,F,L>::result_type,std::string&(__cdecl *)(info
*),A>(boost::_bi::type<T>,F & ,A &,long)' being compiled
        with
        [
            R=boost::_bi::bind_t<std::string &,std::string &(__cdecl
*)(info *),boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>::result_type,
            A1=boost::_bi::list_av_1<boost::arg<1>>::B1,
            F=std::string &(__cdecl *)(info *),
            L=boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>,
            A=const boost::_bi::list1<info &>,
            T=boost::_bi::bind_t<std::string &,std::string &(__cdecl
*)(info *),boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>::result_type
        ]
        c:\boost\boost\bind.hpp(213) : see reference to function
template instantiation 'boost::_bi::bind_t<R,F,L>::result_type
boost::_bi::bind_t<R,F,L>::eval<const boost::_bi::list1<A1>>(A &)'
being compiled
        with
        [
            R=std::string &,
            F=std::string &(__cdecl *)(info *),
            L=boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>,
            A1=info &,
            A=const boost::_bi::list1<info &>
        ]
[snip]

Any ideas?

Christian