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<title>Issue 1090: Missing description of packaged_task member swap,  missing non-member swap</title>
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<p><em>This page is a snapshot from the LWG issues list, see the <a href="lwg-active.html">Library Active Issues List</a> for more information and the meaning of <a href="lwg-active.html#Resolved">Resolved</a> status.</em></p>
<h3 id="1090"><a href="lwg-defects.html#1090">1090</a>. Missing description of <code>packaged_task</code> member <code>swap</code>,  missing non-member <code>swap</code></h3>
<p><b>Section:</b> 32.10.10 <a href="https://wg21.link/futures.task">[futures.task]</a> <b>Status:</b> <a href="lwg-active.html#Resolved">Resolved</a>
 <b>Submitter:</b> Daniel Kr&uuml;gler <b>Opened:</b> 2009-03-22 <b>Last modified:</b> 2016-01-28</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View all other</b> <a href="lwg-index.html#futures.task">issues</a> in [futures.task].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#Resolved">Resolved</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Class template <code>packaged_task</code> in 32.10.10 <a href="https://wg21.link/futures.task">[futures.task]</a> shows a member <code>swap</code>
declaration, but misses to document it's effects (No prototype provided). Further on this class
misses to provide a non-member swap.
</p>

<p><i>[
Batavia (2009-05):
]</i></p>

<blockquote>
<p>
Alisdair notes that paragraph 2 of the proposed resolution has already been
applied in the current Working Draft.
</p>
<p>
We note a pending <code>future</code>-related paper by Detlef;
we would like to wait for this paper before proceeding.
</p>
<p>
Move to Open.
</p>
</blockquote>

<p><i>[
2009-05-24 Daniel removed part 2 of the proposed resolution.
]</i></p>


<p><i>[
2009-10 post-Santa Cruz:
]</i></p>


<blockquote><p>
Move to Tentatively Ready, removing bullet 3 from the proposed
resolution but keeping the other two bullets.
</p></blockquote>

<p><i>[
2010 Pittsburgh:
]</i></p>


<blockquote><p>
Moved to <del>NAD Editorial</del><ins>Resolved</ins>.  Rationale added below.
</p></blockquote>



<p><b>Rationale:</b></p>
<p>
Solved by <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3058.html">N3058</a>.
</p>


<p id="res-1090"><b>Proposed resolution:</b></p>
<ol>
<li>
<p>
In 32.10.10 <a href="https://wg21.link/futures.task">[futures.task]</a>, immediately after the definition of class
template packaged_task add:
</p>
<blockquote><pre>
<ins>
template&lt;class R, class... Argtypes&gt;
void swap(packaged_task&lt;R(ArgTypes...)&gt;&amp;, packaged_task&lt;R(ArgTypes...)&gt;&amp;);
</ins>
</pre></blockquote>
</li>
<li>
<p>
At the end of 32.10.10 <a href="https://wg21.link/futures.task">[futures.task]</a> (after p. 20), add the following
prototype description:
</p>

<blockquote><pre>
<ins>
template&lt;class R, class... Argtypes&gt;
void swap(packaged_task&lt;R(ArgTypes...)&gt;&amp; x, packaged_task&lt;R(ArgTypes...)&gt;&amp; y);
</ins></pre>
<blockquote>
<p><ins>
<i>Effects:</i> <code>x.swap(y)</code>
</ins></p>
<p><ins>
<i>Throws:</i> Nothing.
</ins></p>
</blockquote>
</blockquote>
</li>
</ol>





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