Re: [boost] howto: boost.lambda + stl on VS 2010 (SP1) ?

Subject: Re: [boost] howto: boost.lambda + stl on VS 2010 (SP1) ?
From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2011-05-09 03:16:33

On 05/05/2011 01:37, Raffi Enficiaud wrote:
> Hi all,
>
> Sorry for bothering with this. I recently encountered some problems in using
> boost.lambda with Visual 2010 Express, and need some clues for solving the
> issue (there are many ways around of course).
> I simply want to accumulate the values of a std::map, and I thought using
> lambda to access the second member of the map iterator was appropriate. Here
> is the piece of code:
>
> typedef std::map<T1, unsigned short>  m_t;
> m_t m ; // fill m
> double acc(0);
> std::for_each(m.begin(), m.end(), var(acc) +=&  _1->*&
> m_t::value_type::second);
>
> The last line does not compile on Visual (it does on GCC), I have to add a
> typedef:
>
> typedef typename m_t::value_type aa;
> std::for_each(m.begin(), m.end(), var(acc) +=&  _1->*&  aa::second);
>
> Which one is "more correct" ?

It's one of the annoying MSVC bugs.

MSVC doesn't like it when you chain nested names in template contexts.