Re: [boost] bind and lambda don't work together?

From: Victor A. Wagner, Jr. (vawjr_at_[hidden])
Date: 2003-08-08 20:34:58

thank you
I had a simpler solution, remove the #include boost/bind.hpp
it was some old stuff that hadn't panned out, but the #include never got 
removed.
this causes a small  amount of grief trying to find it, since I couldn't 
remember it being used at all... and it wasn't, but the #include was still 
in one of the header files.
At Friday 2003-08-08 03:16, you wrote:
>Victor A. Wagner, Jr. wrote:
>
> > I finally had a chance to go back and look at an attempt to use lambda in
> > one of my commercial endeavors.  It turns out that I was getting "ambiguous
> > _1" with my compiler (VC.net2003) between lambda and bind.
>
>Boost.lambda places _1 in the boost::lambda namespace.
>Boost.bind places _1 in the global namespace.  This is fine
>so long as you avoid using directives and are careful with
>using declarations.
>
>As soon as you have a using directive for the boost::lambda
>namespace, boost::lambda::_1 will be injected into the
>global namespace -- even if the using directive is at block
>scope -- and any use of _1 will be ambiguous.
>
>If you have translation units that use both Boost.bind and
>Boost.lambda, the safest advice is (i) avoid all using
>directives for namespace boost::lambda; (ii) put using
>declarations at block scope.  For example,
>
>   int main()
>   {
>     boost::function< int (int, int) > times;
>     {
>       using boost::lambda::_1;
>       using boost::lambda::_2;
>       times = _1 * _2;
>     }
>
>     boost::function< int (int) > square
>       ( boost::bind( times, _1, _1 ) );
>
>     std::cout << times(10,20) << std::endl;
>     std::cout << square(9) << std::endl;
>   }
>
>--
>Richard Smith
>_______________________________________________
>Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

Victor A. Wagner Jr.      http://rudbek.com
The five most dangerous words in the English language:
               "There oughta be a law"