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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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17
doc/issues.html
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@ -246,7 +246,7 @@ at <a class="reference" href="http://www.boost.org/LICENSE_1_0.txt">http://www.b
</li>
<li><a class="reference" href="#proposed-solution-in-progress" id="id16" name="id16">Proposed Solution (in progress)</a><ul>
<li><a class="reference" href="#overview" id="id17" name="id17">Overview</a></li>
<li><a class="reference" href="#details" id="id18" name="id18">Details</a></li>
<li><a class="reference" href="#future-enhancements" id="id18" name="id18">Future Enhancements</a></li>
<li><a class="reference" href="#impact-on-n1530-iterator-facade-and-adaptor" id="id19" name="id19">Impact on N1530 (Iterator Facade and Adaptor)</a></li>
</ul>
</li>
@ -470,15 +470,20 @@ information, we'll change <tt class="literal"><span class="pre">iterator_tag</sp
old-style category in terms of the iterator's traversal category,
<tt class="literal"><span class="pre">reference</span></tt>, and <tt class="literal"><span class="pre">value_type</span></tt>.</p>
</div>
<div class="section" id="details">
<h2><a class="toc-backref" href="#id18" name="details">Details</a></h2>
<p>A cleaner solution would change <tt class="literal"><span class="pre">iterator_traits</span></tt> as follows,
though this does not constitute a &quot;pure bolt-on&quot;:</p>
<div class="section" id="future-enhancements">
<h2><a class="toc-backref" href="#id18" name="future-enhancements">Future Enhancements</a></h2>
<p>For C++0x, we could consider a change to <tt class="literal"><span class="pre">iterator_traits</span></tt> 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 &quot;pure bolt-on&quot;:</p>
<pre class="literal-block">
iterator_traits&lt;I&gt;::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&lt;I&gt;::type is void
|| iterator_difference_type&lt;I&gt;::type is void
)
@ -513,7 +518,7 @@ iterator_traits&lt;I&gt;::iterator_category
<hr class="footer" />
<div class="footer">
<a class="reference" href="issues.rst">View document source</a>.
Generated on: 2003-11-06 03:02 UTC.
Generated on: 2003-11-07 19:02 UTC.
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</div>
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13
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
)