[boost] Re: Re: Boost Iterable Range Library update (v1.5)

From: Neal Becker (ndbecker2_at_[hidden])
Date: 2004-11-12 20:29:41

Thorsten Ottosen wrote:

> "Neal D. Becker" <ndbecker2_at_[hidden]> wrote in message
> news:cn35c3$g4g$1_at_sea.gmane.org...
> | John Torjo wrote:
> 
> | > As you probably know, the library is around 1 year old. I've used it
> | > heavily on some of my projects, and all I can say is that iteration
> | > capability has helped me much.
> | >
> |
> | If you write all your algorithms to a range interface instead of
> | iterator
> | interface, that's a big win when you really want ranges.  When you have
> | to
> | manually iterate in a loop, it's a loss.  Now you have to say:
> |
> | template<class in_cont, class out_cont>
> | algorithm (in_cont const& in, out_cont & out) {
> |   typename boost::range_const_iterator<in_cont>::type i = boost::begin
> |   (in); typename boost::range_iterator<out_cont>::type o = boost::begin
> |   (out); for (; i != boost::end (in); ++i, ++o) ...
> |
> | In this case, I'd say it's a net loss.
> 
> Sorry, could you elaborate on what the loss is? Using a new iterable range
> concept we can say
> 
> sub_range<const in_cont> r( in );
> for( ; r; ++r ) { ... }
> 

I'm confused.  We are talking about http://www.torjo.com/rangelib/?  I can't
find any mention of the above "sub_range" in the zip I grabbed from that
site.

> If your question is: "should algorithms be implemented in terms of
> iterators or ranges?",
> then answer is "iterators". However, it makes sense not to expose the
> iterator interface once you
> have added the range layer and the iterator interface might use iterable
> ranges in its implementation.
> 

Don't know what you mean by "in terms of".  I'm thinking that we want
algorithms to use ranges for interfaces, like the example I gave of
"algorithm" above.  Internally, algorithm could use range if it is
convenient, like if we could pass to rng::transform, but in general,
iterators might be necessary.  Is this what you mean?