[Boost-users] Re: [MPL] map question

From: David Abrahams (dave_at_[hidden])
Date: 2004-12-21 09:11:16

Aleksey Gurtovoy wrote:

> Answering the OP question: MPL lambda expressions do not support scopes (yet),
> so it's not possible to implement the above without an auxiliary metafunction 
> incapsulating the nested scope. Which actually might be a good thing -- it's 
> hard to imagine that the "inline" version would be shorter and easier to 
> understand than this:
> 
>     template< typename Map, typename Entry >
>     struct copy_entires
>         : copy< 
>               typename Entry::second::entries
>             , inserter<Map, insert<_1,_2> >
>             >
>     {
>     };
> 
>     typedef fold<map_types, map_types, copy_entires<_1,_2> >::type result;

In that case, can you explain what protect<> is for?

Thanks,

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com