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[SVN r20728]
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Dave Abrahams
2003-11-07 19:03:58 +00:00
parent 81870ac8b6
commit fed5967d9d
2 changed files with 20 additions and 10 deletions
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doc/issues.rst
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@ -260,16 +260,21 @@ information, we'll change ``iterator_tag`` so that it computes the
old-style category in terms of the iterator's traversal category,
``reference``, and ``value_type``.
Details
=======
Future Enhancements
===================
A cleaner solution would change ``iterator_traits`` as follows,
though this does not constitute a "pure bolt-on"::
For C++0x, we could consider a change to ``iterator_traits`` which
allows the user to avoid the use of iterator_tag (or similar
devices) altogether and write a new-style iterator by specifying
only a traversal tag. This change is not being proposed as it does
not constitute a "pure bolt-on"::
iterator_traits<I>::iterator_category
= if (I::iterator_category is a type) // use mpl::has_xxx (SFINAE)
return I::iterator_category
// Only old-style output iterators may have a void value_type
// or difference_type
if (iterator_value_type<I>::type is void
|| iterator_difference_type<I>::type is void
)