[Boost-users] Question Regarding Boost 1.33.1 on MSVC.NET 2003

From: Wu Yinghui, Freddie (yhwu_at_[hidden])
Date: 2006-01-11 01:57:23

Hi all,

I'm having a problem using Boost.Bind on the above platform.

The simple test file I'm using looks like this:

=== snip ===
#include <iostream>
#include <algorithm>
#include <map>
#include <boost/bind.hpp>

struct Argument
{
     int value_;
};

struct Operator
{
     Operator &compute(Argument const &arg)
     {
         std::cout << arg.value_ << std::endl;
         return *this;
     }
     // Warning is gone if I declare the above function as:
     //Operator const &compute(Argument const &arg) const {...}
};

int main()
{
     typedef std::map<int, Operator> OperatorMap;

     OperatorMap ops;
     ops.insert(std::make_pair(0, Operator()));

     Argument arg0 = { 1 };

     std::for_each(
         ops.begin(), ops.end(),
         boost::bind(&Operator::compute,
                     boost::bind(&OperatorMap::value_type::second, _1),
                     boost::cref(arg0)));
}
=== snip ===

The idea is that I want to put a parameter through a collection of 
Operators objects stored in an std::map. However, I always get the 
following warning from the compiler:

=== snip ===
test.cpp
..\..\..\boost-1.x\include\boost-1_33_1\boost\bind.hpp(276) : warning 
C4239: nonstandard extension used : 'argument' : conversion from 
'boost::_bi::result_traits<R,F>::type' to 'Operator &'
         with
         [
             R=Operator,
             F=boost::_mfi::dm<Operator,stlp_std::pair<const int,Operator>>
         ]
         A reference that is not to 'const' cannot be bound to a non-lvalue
 
..\..\..\boost-1.x\include\boost-1_33_1\boost\bind\bind_template.hpp(32) 
: see reference to function template instantiation 'R 
boost::_bi::list2<A1,A2>::operator 
()<boost::_bi::bind_t<R,F,L>::result_type,F,boost::_bi::list1<stlp_std::pair<_T1,_T2> 
&>>(boost::_bi::type<T>,F &,A &,long)' being compiled
         with
         [
             R=boost::_bi::bind_t<Operator &,boost::_mfi::mf1<Operator 
&,Operator,const Argument 
&>,boost::_bi::list2<boost::_bi::list_av_2<boost::_bi::bind_t<Operator,boost::_mfi::dm<Operator,stlp_std::pair<const 
int,Operator>>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,Argument>::B1,boost::_bi::list_av_2<boost::_bi::bind_t<Operator,boost::_mfi::dm<Operator,stlp_std::pair<const 
int,Operator>>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,Argument>::B2>>::result_type,
 
A1=boost::_bi::list_av_2<boost::_bi::bind_t<Operator,boost::_mfi::dm<Operator,stlp_std::pair<const 
int,Operator>>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,Argument>::B1,
 
A2=boost::_bi::list_av_2<boost::_bi::bind_t<Operator,boost::_mfi::dm<Operator,stlp_std::pair<const 
int,Operator>>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,Argument>::B2,
             F=boost::_mfi::mf1<Operator &,Operator,const Argument &>,
 
L=boost::_bi::list2<boost::_bi::list_av_2<boost::_bi::bind_t<Operator,boost::_mfi::dm<Operator,stlp_std::pair<const 
int,Operator>>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,Argument>::B1,boost::_bi::list_av_2<boost::_bi::bind_t<Operator,boost::_mfi::dm<Operator,stlp_std::pair<const 
int,Operator>>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,Argument>::B2>,
             _T1=const int,
             _T2=Operator,
             T=boost::_bi::bind_t<Operator &,boost::_mfi::mf1<Operator 
&,Operator,const Argument 
&>,boost::_bi::list2<boost::_bi::list_av_2<boost::_bi::bind_t<Operator,boost::_mfi::dm<Operator,stlp_std::
pair<const 
int,Operator>>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,Argument>::B1,boost::_bi::list_av_2<boost::_bi::bind_t<Operator,boost::_mfi::dm<Operator,stlp_std::pair<const 
int,Operator>>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,Argument>::B2>>::result_type,
             A=boost::_bi::list1<stlp_std::map<int,Operator>::value_type &>
         ]
         ..\..\..\STLport-5.0\stlport\stl\_algo.h(61) : see reference to 
function template instantiation 'boost::_bi::bind_t<R,F,L>::result_type 
boost::_bi::bind_t<R,F,L>::operator ()<_Tp>(A1 &)' being compiled
         with
         [
             R=Operator &,
             F=boost::_mfi::mf1<Operator &,Operator,const Argument &>,
 
L=boost::_bi::list2<boost::_bi::list_av_2<boost::_bi::bind_t<Operator,boost::_mfi::dm<Operator,stlp_std::pair<const 
int,Operator>>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,Argument>::B1,boost::_bi::list_av_2<boost::_bi::bind_t<Operator,boost::_mfi::dm<Operator,stlp_std::pair<const 
int,Operator>>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,Argument>::B2>,
             _Tp=stlp_std::map<int,Operator>::value_type,
             A1=stlp_std::map<int,Operator>::value_type
         ]
 
\workspace\devel\RD3.0-vc71\Libraries\MkToolkit-3.0\src\core\test.cpp(35) 
: see reference to function template instantiation '_Function 
stlp_std::for_each<stlp_std::map<_Key,_Tp>::iterator,boost::_bi::bind_t<R,F,L>>(_InputIter,_InputIter,_Function)' 
being compiled
         with
         [
             _Function=boost::_bi::bind_t<Operator 
&,boost::_mfi::mf1<Operator &,Operator,const Argument 
&>,boost::_bi::list2<boost::_bi::list_av_2<boost::_bi::bind_t<Operator,boost::_mfi::dm<Operator,stlp_std::pair<const 
int,Operator>>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,Argument>::B1,boost::_bi::list_av_2<boost::_bi::bind_t<Operator,boost::_mfi::dm<Operator,stlp_std::pair<const 
int,Operator>>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,Argument>::B2>>,

      _Key=int,
             _Tp=Operator,
             R=Operator &,
             F=boost::_mfi::mf1<Operator &,Operator,const Argument &>,
 
L=boost::_bi::list2<boost::_bi::list_av_2<boost::_bi::bind_t<Operator,boost::_mfi::dm<Operator,stlp_std::pair<const 
int,Operator>>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,Argument>::B1,boost::_bi::list_av_2<boost::_bi::bind_t<Operator,boost::_mfi::dm<Operator,stlp_std::pair<const 
int,Operator>>,boost::_bi::list1<boost::_bi::list_av_1<boost::arg<1>>::B1>>,Argument>::B2>,
             _InputIter=stlp_std::map<int,Operator>::iterator
         ]
=== snip ===

It seems that it is complaining about the const-ness of 
Operator::compute() member function. May I know if there is anything I 
can do to fix this problem? Or, is there any problem with my 
understanding of Boost.Bind through the way I used it?

Cheers,

Freddie

-- 
Wu Yinghui, Freddie
Research & Development
Software Engineer
Volume Interactions Pte Ltd
1 Kim Seng Promenade, #12-01
Great World City East Tower
Singapore 237994
Tel:   [phone] (Ext 216)
Fax:   [phone]
Email: yhwu_at_[hidden]
URL:   http://www.volumeinteractions.com
Important:  This message is intended for the recipient(s) addressed 
above.  It contains privileged and confidential information.  If you are 
not the intended recipient, please notify the sender immediately by 
replying to this message and then delete it from your system.  You must 
not read, copy, use, or disseminate this communication in any form. 
Thank you.