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<title>Issue 107: Valarray constructor is strange</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#NAD">NAD</a> status.</em></p>
<h3 id="107"><a href="lwg-closed.html#107">107</a>. Valarray constructor is strange</h3>
<p><b>Section:</b> 29.6.2 <a href="https://wg21.link/template.valarray">[template.valarray]</a> <b>Status:</b> <a href="lwg-active.html#NAD">NAD</a>
 <b>Submitter:</b> AFNOR <b>Opened:</b> 1998-10-07 <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#template.valarray">issues</a> in [template.valarray].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#NAD">NAD</a> status.</p>
<p><b>Discussion:</b></p>
<p>The order of the arguments is (elem, size) instead of the normal
(size, elem) in the rest of the library. Since elem often has an
integral or floating point type, both types are convertible to each
other and reversing them leads to a well formed program.</p>


<p id="res-107"><b>Proposed resolution:</b></p>
<p>Inverting the arguments could silently break programs. Introduce
the two signatures (const T&amp;, size_t) and (size_t, const T&amp;),
but make the one we do not want private so errors result in a
diagnosed access violation. This technique can also be applied to STL
containers.</p>


<p><b>Rationale:</b></p>
<p>The LWG believes that while the order of arguments is unfortunate,
it does not constitute a defect in the standard. The LWG believes that
the proposed solution will not work for valarray&lt;size_t&gt; and
perhaps other cases.</p>




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