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<title>Issue 745: copy_exception API slices.</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="745"><a href="lwg-closed.html#745">745</a>. copy_exception API slices.</h3>
<p><b>Section:</b> 17.9.7 <a href="https://wg21.link/propagation">[propagation]</a> <b>Status:</b> <a href="lwg-active.html#NAD">NAD</a>
 <b>Submitter:</b> Alisdair Meredith <b>Opened:</b> 2007-10-10 <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#propagation">issues</a> in [propagation].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#NAD">NAD</a> status.</p>
<p><b>Discussion:</b></p>
<p>
It could be I did not understand the design rationale, but I thought
copy_exception would produce an exception_ptr to the most-derived (dynamic)
type of the passed exception.  Instead it slices, which appears to be less
useful, and a likely source of FAQ questions in the future.
</p>
<p>
(Peter Dimov suggests NAD)
</p>

<p><i>[
Bellevue: 
]</i></p>


<blockquote>
<p>
How could this be implemented in a way that the dynamic type is cloned?
</p>
<p>
The feature is designed to create an exception_ptr from an object whose
static type is identical to the dynamic type and thus there is no
slicing involved.
</p>
</blockquote>


<p id="res-745"><b>Proposed resolution:</b></p>
<p>
</p>





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