[Bug libstdc++/15910] can't compile self defined void distance(std::vector<T>, std::vector<T>)

[gdr at integrable-solutions dot net]

------- Additional Comments From gdr at integrable-solutions dot net  2004-08-03 15:19 -------
Subject: Re:  can't compile self defined void distance(std::vector<T>, std::vector<T>)

"giovannibajo at libero dot it" <gcc-bugzilla@gcc.gnu.org> writes:

| Subject: Re:  can't compile self defined void distance(std::vector<T>, std::vector<T>)
| 
| pcarlini at suse dot de wrote:
| 
| > First, the ongoing work on type traits + tr1 may simplify
| > considerably this kind of refinements, exploting enable_if idioms.
| 
| OK. Meanwhile, so that it does not seem I am here just to do FUD, this is
| another proto-patch to fix this bug. This solution seems almost perfect to me:
| 
| 
| template <class Iter>
| typedef typename lazy_enable_if<
|     has_difference_type<iterator_traits<T> >,
|     get_difference_type<iterator_traits<T> >
| >::type
| distance(Iter first, Iter last) { ... }

Please, do understand that
  
  (1) you're changing the signature of this template function;  I see
      nothing in the standard that allows this transmutation.  I would
      welcome any quote to that effect.

  (2) focusing on distance is wrong:  It is just the tip of the iceberg.

[...]

| > Second, if we really want to go this way, we should do it
| > consistently: don't you believe that most definitely *many* other
| > places of the library could be amenable to this treatment?
| 
| I don't know how many off-hand.

Every places where the constraints on the template parameter are in
comments, not in actual codes.  And there are lots of them.

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15910