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| <a name="boost_optional.type_requirements"></a><a class="link" href="type_requirements.html" title="Type requirements">Type requirements</a> |
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| <p> |
| At the very minimum for <code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> |
| to work with a minimum interface it is required that <code class="computeroutput"><span class="identifier">T</span></code> |
| has a publicly accessible no-throw destructor. In that case you need to initialize |
| the optional object with function <code class="computeroutput"><span class="identifier">emplace</span><span class="special">()</span></code> or use <span class="bold"><strong>InPlaceFactories</strong></span>. |
| Additionally, if <code class="computeroutput"><span class="identifier">T</span></code> is <code class="computeroutput"><span class="identifier">Moveable</span></code>, <code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> |
| is also <code class="computeroutput"><span class="identifier">Moveable</span></code> and can be |
| easily initialized from an rvalue of type <code class="computeroutput"><span class="identifier">T</span></code> |
| and be passed by value. Additionally, if <code class="computeroutput"><span class="identifier">T</span></code> |
| is <code class="computeroutput"><span class="identifier">Copyable</span></code>, <code class="computeroutput"><span class="identifier">optional</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span></code> is |
| also <code class="computeroutput"><span class="identifier">Copyable</span></code> and can be easily |
| initialized from an lvalue of type <code class="computeroutput"><span class="identifier">T</span></code>. |
| </p> |
| <p> |
| <code class="computeroutput"><span class="identifier">T</span></code> <span class="underline">is |
| not</span> required to be <a href="http://www.sgi.com/tech/stl/DefaultConstructible.html" target="_top">Default |
| Constructible</a>. |
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| <td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<br>Copyright © 2014 Andrzej Krzemieński<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) |
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