Re: [boost] [fusion] Short-circuited Exception-based View Iteration

From: Joel de Guzman (joel_at_[hidden])
Date: 2007-09-24 04:20:53

shunsuke wrote:
> Dean Michael Berris wrote:
>> struct equals_2 {
>>   template <typename T>
>>   T operator() (T element) const {
>>     if (element == 2) return element;
>>   };
>> };
>>
>> typedef fusion::tuple<int, int, int> point_type;
>> point_type point(1, 2, 3);
>> assert(fusion::is_homogenous<point_type>::value == true);
>> assert(fusion::find_first_if<equals_2>(point) == 2); // only works if
>> 'point' is a homogeneous container
> 
> FWIW, a few weeks ago, I had a radical idea
> about an iterator which runs through a tuple/fusion.
> 
> rectangle r; triangle t; circle c;
> boost::tuple<rectangle*, triangle*, circle*> tup(&r, &t, &c);
> BOOST_FOREACH (shape *s, oven::hetero<shape *>(tup)) {
>      s->draw();
> }
> 
> If interested, here is the implementation: http://tinyurl.com/2gojyw

I'm interested! This ought to be part of fusion :-)

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