Re: [boost] [Fusion] Heads up

From: Joel de Guzman (joel_at_[hidden])
Date: 2006-08-30 20:36:13

David Abrahams wrote:
> Joel de Guzman <joel_at_[hidden]> writes:
> 
>> Joel de Guzman wrote:
>>> Hello,
>>>
>>> I shall be putting Fusion in the CVS (HEAD) soon. The old
>>> Fusion(1) under the Spirit directory will cease to exist.
>>> I shall try to adjust all boost libraries that rely on it
>>> to use the new Fusion2 instead.
>> Fusion2 is in CVS now. I adjusted tr1::tuple to use Fusion2
>> instead. 
> 
> Totally cool!
> 
> Did you write the necessary components to make boost::tuple and
> boost::cons conforming fusion tuples?

Not yet. There are still lots of work to do, but that's a high item
in the todo list. One higher priority item is to make it easier to
make conforming fusion sequences. It would be a good idea to do that
first and leverage that for boost::cons. There's also an interesting
use-case that became apparent recently: making arbitrary structs/classes
conforming sequences easily-- as easy as providing a single function.
Pardon me if this is rather sketchy at this point, but imagine
being able to write:

Our user defined struct:

     struct point { float x, float y; };

Customization:

     fusion::map<keys::x_, keys::y_, float&, float&>
     as_fusion_sequence(point& p)
     {
         return fusion::map_tie<keys::x_, keys::y_>(p.x, p.y);
     }

Use:

     point p = { 123.456, 789.012 };
     fusion::for_each(p, std::cout << _1 << std::endl);

Regards,
-- 
Joel de Guzman
http://www.boost-consulting.com
http://spirit.sf.net