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<title>Issue 1508: Rename packaged_task::operator bool()</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="1508"><a href="lwg-defects.html#1508">1508</a>. Rename <code>packaged_task::operator bool()</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> INCITS <b>Opened:</b> 2010-08-25 <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><b>Addresses US-201</b></p>
<p>
<code>packaged_task</code> provides <code>operator bool()</code> to check whether
an object has an associated asynchronous state. The various <code>future</code> 
types provide a member function <code>valid()</code> that does the same thing. 
The names of these members should be the same.
</p>

<p><i>[
Resolution proposed by ballot comment:
]</i></p>

<blockquote><p>
Replaced the name <code>packaged_task::operator bool()</code> with <code>packaged_task::valid()</code> in the synopsis
(32.10.10 <a href="https://wg21.link/futures.task">[futures.task]</a>/2) and the member function specification (before 32.10.10.2 <a href="https://wg21.link/futures.task.members">[futures.task.members]</a>/15).
</p></blockquote>

<p><i>[
2010-11-02 Daniel translates proposed wording changes into a proper proposed resolution
and verified that no other places implicitly take advantage of <code>packaged_task</code> 
conversion to bool.
]</i></p>


<p><i>[Resolved in Batavia by accepting
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3194.htm">n3194</a>.
]</i></p>




<p id="res-1508"><b>Proposed resolution:</b></p>
<ol>
<li>Change 32.10.10 <a href="https://wg21.link/futures.task">[futures.task]</a>/2, class template <code>packaged_task</code> synopsis as indicated:
<blockquote><pre>
template&lt;class R, class... ArgTypes&gt;
class packaged_task&lt;R(ArgTypes...)&gt; {
public:
  typedef R result_type;
  [..]
  <del>explicit operator</del> bool <ins>valid</ins>() const;
  [..]
};
</pre></blockquote>
</li>
<li>Change 32.10.10 <a href="https://wg21.link/futures.task">[futures.task]</a> before p. 15 as indicated:
<blockquote><pre>
<del>explicit operator</del> bool <ins>valid</ins>() const;
</pre><blockquote><p>
15 <em>Returns</em>: true only if <code>*this</code> has an associated asynchronous state.
<p/>
16 <em>Throws</em>: nothing.
</p></blockquote></blockquote>
</li>
</ol>





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