Re: [Boost-users] [iterator] make_zip_iterator

From: shunsuke (pstade.mb_at_[hidden])
Date: 2007-02-17 20:19:03

Robert Ramey wrote:
> Well, I would like to take this opportunity to plug "dataflow iterators" 
> which is part of the serialization library.
> 
> I wanted the following:
> 
> a) to be able to compose iterators at to any reasonable depth
> b) that such a composition occur at compile time.
> c) to permit a composition to be predefined so it could be used in
> any subsequent composition.
> 
> I first considered making functions like the one you propose - 
> make_?_iterator.
> It didn't seem to me that it was going to satisfy the wish list as stated 
> above.
> Finally, I found that just by adding to each iterator adaptor a templated 
> constructor of the form
> 
> // note BaseIterator DOES NOT refer to a base class.  It refers to an 
> iterator
> // whose behavior is going to be modified by my_iterator.
> 
> template<class BaseIterator>
> my_iterator(BaseIterator &bi) : ...
> 
> I could realize all goals stated above.
> 
> This permited me to build a complex iterator such as convert binary code to 
> base64 by
> building and testing much simpler constituent iterators and composing them 
> at compile time.
> I applied it to streams of characters - but I don't think that would be any 
> less useful when
> applied to something like tuples.

I tend to think that Boost.Range concept is more cute.
That is, 'rng|zipped'.
Also, I found Range can be recursive a few weeks ago.
If you're interested, see: http://tinyurl.com/2o2mnv
This is a hopeless war on functional languages. :-)

Regards,

-- 
Shunsuke Sogame