Thorsten Ottosen wrote:
"Pavel Vozenilek" <pavel_vozenilek@hotmail.com> wrote in message news:c6s7rh$fc9$1@sea.gmane.org... | I wonder whether Collection Traits can also use Filter Iterator | (http://www.boost.org/libs/iterator/doc/filter_iterator.html) | as 'collection'.
nope. The requierement is that a default constructed iterator denotes the end.
I think it's possible to create iterator adaptor which makes default constructed iterator denote the end. Hey, it's 10 mins effort, see http://zigzag.cs.msu.su:7813/implicit_eof_iterator I'm not yet sure if this is better/worse than views, but definitely Collection Traits need to have special support for Filter iterator. Either we need views, or we need such wrapper iterator.
| Or even whether it can simplify use of Filter Iterator a bit.
I think the key for simpler use of all of the iterators in Boost.Iterator is to define special range versions of make_XX. I hope John and Matthew will do this in their range lib.
Where can I look at this lib, and how it's different/related to the views library in the sandbox?
For example
make_filter_range( is_positive_number(), coll );
Using Collection Traits that should be simple. So eventually we can write
std::copy( boost::make_filter_range( is_positive_number(), numbers ), std::ostream_iterator<int>( std::cout, " " ) )
Yes, that's what I'd like. Only, I *really* think that the function should be called just 'filter'. But that's just personal opinion. - Volodya