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<title>Issue 748: The is_abstract type trait is defined by reference to 10.4.</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="748"><a href="lwg-closed.html#748">748</a>. The is_abstract type trait is defined by reference to 10.4.</h3>
<p><b>Section:</b> 21.3.6.4 <a href="https://wg21.link/meta.unary.prop">[meta.unary.prop]</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>
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<p><b>Discussion:</b></p>
<p>
I am trying to decide is a pure virtual function is a <i>necessary</i> as well as
sufficient requirement to be classified as abstract?
</p>
<p>
For instance, is the following (non-polymorphic) type considered abstract?
</p>
<blockquote><pre>
struct abstract {
protected:
 abstract(){}
 abstract( abstract const &amp; ) {}
 ~abstract() {}
};
</pre></blockquote>
<p>
(Suggested that this may be NAD, with an editorial fix-up from Pete on the
core wording to make clear that abstract requires a pure virtual function)
</p>


<p id="res-748"><b>Proposed resolution:</b></p>
<p>
Core has clarified that the definition abstract is adequate. Issue withdrawn by submitter. NAD.
</p>





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