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<title>Issue 2027: Initialization of the stored task of a packaged_task</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#C++11">C++11</a> status.</em></p>
<h3 id="2027"><a href="lwg-defects.html#2027">2027</a>. Initialization of the stored task of a <code>packaged_task</code></h3>
<p><b>Section:</b> 32.10.10.2 <a href="https://wg21.link/futures.task.members">[futures.task.members]</a> <b>Status:</b> <a href="lwg-active.html#C++11">C++11</a>
 <b>Submitter:</b> Alberto Ganesh Barbati <b>Opened:</b> 2011-02-09 <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.members">issues</a> in [futures.task.members].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#C++11">C++11</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Related with LWG issue <a href="lwg-defects.html#1514" title="packaged_task constructors need review (Status: C++11)">1514</a><sup><a href="https://cplusplus.github.io/LWG/issue1514" title="Latest snapshot">(i)</a></sup>.
</p>

<p>
The move constructor of <code>packaged_task</code> does not specify how the stored task is constructed. 
The obvious way is to move-construct it using the task stored in the argument. Moreover, the 
constructor should be provided with a throws clause similar to one used for the other constructors, 
as the move constructor of the stored task is not required to be nothrow.</p>

<p>
As for the other constructors, the terms "stores a copy of <code>f</code>" do not reflect the intent, which is 
to allow <code>f</code> to be moved when possible.
</p>

<p><i>[2011-02-25: Alberto updates wording]</i></p>


<p><i>[2011-02-26 Reflector discussion]</i></p>

<p>
Moved to Tentatively Ready after 5 votes.
</p> 


<p id="res-2027"><b>Proposed resolution:</b></p>
<p>(wording written assuming LWG <a href="lwg-defects.html#1514" title="packaged_task constructors need review (Status: C++11)">1514</a><sup><a href="https://cplusplus.github.io/LWG/issue1514" title="Latest snapshot">(i)</a></sup> is also accepted)</p>

<ol>
<li>
<p>Change 32.10.10.2 <a href="https://wg21.link/futures.task.members">[futures.task.members]</a> paragraph 3:</p>

<blockquote><p>
3 <em>Effects</em>: constructs a new <code>packaged_task</code> object with an associated asynchronous state and <del>stores a
copy of <code>f</code> as the object's stored task</del><ins>initializes the object's stored task with <code>std::forward&lt;F&gt;(f)</code></ins>. 
The constructors that take an <code>Allocator</code> argument use it to allocate memory needed to store the internal data structures.
</p></blockquote>

</li>

<li>
<p>Change 32.10.10.2 <a href="https://wg21.link/futures.task.members">[futures.task.members]</a> paragraph 5:</p>

<blockquote><p>
5 <em>Effects</em>: constructs a new <code>packaged_task</code> object and transfers ownership of <code>other</code>'s associated asynchronous
state to <code>*this</code>, leaving <code>other</code> with no associated asynchronous state. <ins>Moves the stored task from <code>other</code> 
to <code>*this</code>.</ins>
</p></blockquote>

</li>

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