Re: [Boost-users] bind, and member function with a parameter

From: David Abrahams (dave_at_[hidden])
Date: 2006-09-13 21:16:02

"Peter Dimov" <pdimov_at_[hidden]> writes:

>
> Your code is fine, sort of. The problem is that vector<>::resize takes two 
> arguments. The second one has a default, but this information is lost when 
> the pointer to member &std::vector<bool>::resize is taken. So you have to 
> pass a value for it.
>
>     std::for_each(vec.begin(),vec.end()
>         ,boost::bind( &std::vector<bool>::resize, _1, 10, false ) );

And then there's the minor detail that you're not allowed to take the
address of standard library (member) functions...  to be technically
portable and correct, you need to write a wrapper, e.g.

   struct resize_vector_bool
   {
        template <class V, class N>
        void operator()(V& v, N n) const
        {
             v.resize(n);
        }
   };

and then you can go back to using two arguments:

    std::for_each(
         vec.begin(), vec.end()
       , boost::bind( resize_vector_bool(), _1, 10));

[unless we repealed that restriction in the committee while I wasn't looking]

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com