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<title>Issue 2207: basic_string::at should not have a Requires clause</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++14">C++14</a> status.</em></p>
<h3 id="2207"><a href="lwg-defects.html#2207">2207</a>. <code>basic_string::at</code> should not have a Requires clause</h3>
<p><b>Section:</b> 27.4.3.6 <a href="https://wg21.link/string.access">[string.access]</a> <b>Status:</b> <a href="lwg-active.html#C++14">C++14</a>
 <b>Submitter:</b> Nevin Liber <b>Opened:</b> 2012-10-26 <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#string.access">issues</a> in [string.access].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#C++14">C++14</a> status.</p>
<p><b>Discussion:</b></p>

<p>
<code>basic_string::at()</code> has a wide contract and should not have a "Requires" clause on it.
</p>

<p><i>[2013-01-17, Juan Soulie comments]</i></p>


<p>This issue would also apply to every member function of <code>basic_string</code> that throws 
<code>out_of_range</code>, and to some cases where a <code>length_error</code> can be thrown.</p>

<p><i>[2013-03-15 Issues Teleconference]</i></p>

<p>
Moved to Review.
</p>
<p>
While this could simply move to Ready on inspection, there is concern that this will not be the
only such case.  Alisdair volunteers to review clause 21/23 for more of such issues for Bristol,
and update the proposed resolution as necessary.
</p>

<p><i>[2013-04-18, Bristol]</i></p>




<p id="res-2207"><b>Proposed resolution:</b></p>
<p>This wording is relative to N3376.</p>

<ol>
<li><p>Remove 27.4.3.6 <a href="https://wg21.link/string.access">[string.access]</a> p5:</p>

<blockquote><pre>
const_reference at(size_type pos) const;
reference at(size_type pos);
</pre><blockquote>
<p>
<del>-5- <i>Requires</i>: <code>pos &lt; size()</code></del>
<p/>
-6- <i>Throws</i>: <code>out_of_range</code> if <code>pos &gt;= size()</code>.
<p/>
-7- <i>Returns</i>: <code>operator[](pos)</code>.
</p>
</blockquote></blockquote>

</li>
</ol>






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