[bind] [lambda] making lambda::bind work

1 Sep 2008

      Hello,

I've got some code that works ok with boost::bind and I'm trying to make it work with lambda::bind but am getting compilation errors. Why not leave it as-is? Just above the problem area of code I have another lambda expression and because I've already introduced lambda's _1 placeholder into the current scope and didn't want ambiguities arising so want to convert it over.

I'm using VC++ 7.1 (2003) and Boost 1.35.0.

I've created a stripped down test program to show the compilation problem:

#include <algorithm>
#include <memory>
#include <string>
#include <vector>
#include 
#include 
#include 
#include 

class GridItem : boost::noncopyable
{
public:
 bool AddOption(const char* item,bool unique = true)
 {
  // implementation code omitted!
  return true;
 }
};

void GoodOldBoostBind()
{
 std::auto_ptr<GridItem> item(new GridItem());
 std::vectorstd::string options;

 std::for_each(options.begin(),options.end(),
  boost::bind(GridItem::AddOption,boost::ref(item),boost::bind(std::string::c_str,_1),true));
}

void LambdaBind()
{
 std::auto_ptr<GridItem> item(new GridItem());
 std::vectorstd::string options;

 using namespace boost::lambda;
 using boost::lambda::_1;
 std::for_each(options.begin(),options.end(),
  bind(GridItem::AddOption,boost::ref(item),bind(std::string::c_str,_1),true));
 // COMPILE ERROR ON ABOVE
}

int main()
{
}

The error is:
c:\releases\lib\boost\boost_1_35_0\include\boost\bind.hpp(338) : error C2664: 'R boost::_mfi::mf2::operator ()>(const U &,A1,A2) const' : cannot convert parameter 2 from 'boost::lambda::lambda_functor<T>' to 'const char *'
        with
        [
            R=bool,
            T=GridItem,
            A1=const char *,
            A2=bool,
            _Ty=GridItem,
            U=std::auto_ptr<GridItem>
        ]
        and
        [
            T=boost::lambda::lambda_functor_base>,boost::tuples::tuple::* const )(void) const>::type,const boost::lambda::detail::bind_traits<const boost::lambda::placeholder1_type>::type,boost::lambda::detail::bind_traitsboost::tuples::null_type::type,boost::lambda::detail::bind_traitsboost::tuples::null_type::type,boost::lambda::detail::bind_traitsboost::tuples::null_type::type,boost::lambda::detail::bind_traitsboost::tuples::null_type::type,boost::lambda::detail::bind_traitsboost::tuples::null_type::type,boost::lambda::detail::bind_traitsboost::tuples::null_type::type,boost::lambda::detail::bind_traitsboost::tuples::null_type::type,boost::lambda::detail::bind_traitsboost::tuples::null_type::type>>
        ]
        No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called

Can anyone help with this?

Thanks,

Pete

Peter Barker

Peter Dimov

Peter Barker

Peter Barker

Peter Dimov

Peter Barker

Alexander

Peter Dimov

Alexander Gutenev

tags

participants (4)