[Boost-users] Re: Iterators

From: Witz (witz_at_[hidden])
Date: 2004-04-15 03:30:28

> > if it was possible it would allow us to write, for example:
> >
> > copy( make_filter_iterator<is_positive_number>(numbers, numbers + N),
> >       numbers + N, ostream_iterator<int>(cout, " "));
> >
> > rather than:
> >
> > copy( make_filter_iterator<is_positive_number>(numbers, numbers + N),
> >       make_filter_iterator<is_positive_number>(numbers + N, numbers + N),
> >       ostream_iterator<int>(cout, " "));
> >
> > of course i am aware that i might be missing something obvious ...
> 
> I think you are.  the signature of std::copy is:
> 
>   template<class InputIterator, class OutputIterator>
>   OutputIterator copy(
>      InputIterator first, InputIterator last, OutputIterator result);
> 
> What will the compiler deduce InputIterator to be?
> 

you are right of course - which is a shame.

for my own use, however, i would happily rewrite the stl algorithms to allow 
for this usage. i often find i have issues with that area of the standard 
library in any case: why does binary_search not return an iterator to the 
item i'm searching for? why min_element, max_element when best_element, 
worst_element is less confusing? why no copy_if? etc. of course that could 
just be me :)

ian whittley