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<title>Issue 1313: Seed sequence's param function not useful for pure output iterator</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="1313"><a href="lwg-closed.html#1313">1313</a>. Seed sequence's param function not useful for pure output iterator</h3>
<p><b>Section:</b> 29.5.8.1 <a href="https://wg21.link/rand.util.seedseq">[rand.util.seedseq]</a> <b>Status:</b> <a href="lwg-active.html#NAD">NAD</a>
 <b>Submitter:</b> Daniel Kr&uuml;gler <b>Opened:</b> 2010-02-07 <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#rand.util.seedseq">issues</a> in [rand.util.seedseq].</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 Seed sequence requirements (29.5.3.2 <a href="https://wg21.link/rand.req.seedseq">[rand.req.seedseq]</a>) require the
existence of a member function
</p>

<blockquote><pre>
template&lt;typename OutputIterator&gt;
void param(OutputIterator ob);
</pre></blockquote>

<p>
The fact that this function returns <code>void</code> instead of the value of
<code>ob</code> after accepting the sequence data leads to the same problem as in
issue <a href="lwg-defects.html#865" title="More algorithms that throw away information (Status: C++11)">865</a><sup><a href="https://cplusplus.github.io/LWG/issue865" title="Latest snapshot">(i)</a></sup> - In case of pure output iterators there is no way to
serialize further data into that data sink.
</p>

<p><i>[
2010-02-07 Howard adds:
]</i></p>


<blockquote><p>
At the time this issue was opened, the suggested changes are with respect to an
anticipated draft which does not yet exist.
</p></blockquote>

<p><i>[
2010 Pittsburgh:
]</i></p>


<blockquote><p>
No technical counterarguments, but it is simply too late in the process
to make this change at this point.
</p></blockquote>


<p id="res-1313"><b>Proposed resolution:</b></p>
<ol>
<li>
<p>
In Table 109 &mdash; Seed sequence requirements, expression "<code>r.param(ob)</code>"
change the<br/>
Return type entry:
</p>

<blockquote><pre>
<del>void</del><ins>OutputIterator</ins>
</pre></blockquote>
</li>

<li>
<p>
In 29.5.8.1 <a href="https://wg21.link/rand.util.seedseq">[rand.util.seedseq]</a>, class seed_seq synopsis change
</p>

<blockquote><pre>
template&lt;class OutputIterator&gt;
<del>void</del><ins>OutputIterator</ins> param(OutputIterator dest) const;
</pre></blockquote>
</li>

</ol>






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