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boost::none is constexpr-declared

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Andrzej Krzemienski
2020-10-24 17:17:10 +02:00
parent 2b08711ec6
commit 7e0b8145b5
45 changed files with 139 additions and 120 deletions
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doc/html/boost_optional/tutorial/design_overview.html
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<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Design Overview</title>
<link rel="stylesheet" href="../../../../../../doc/src/boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets Vsnapshot">
@@ -65,8 +65,8 @@
<code class="computeroutput"><span class="identifier">npos</span></code>, -1, etc... This is
equivalent to adding the special value to the set of possible values of
a given type. This super set of <code class="computeroutput"><span class="identifier">T</span></code>
plus some <span class="emphasis"><em>nil_t</em></span>&#8212;where <code class="computeroutput"><span class="identifier">nil_t</span></code>
is some stateless POD&#8212;can be modeled in modern languages as a <span class="bold"><strong>discriminated union</strong></span> of T and nil_t. Discriminated
plus some <span class="emphasis"><em>nil_t</em></span>—where <code class="computeroutput"><span class="identifier">nil_t</span></code>
is some stateless POD—can be modeled in modern languages as a <span class="bold"><strong>discriminated union</strong></span> of T and nil_t. Discriminated
unions are often called <span class="emphasis"><em>variants</em></span>. A variant has a
<span class="emphasis"><em>current type</em></span>, which in our case is either <code class="computeroutput"><span class="identifier">T</span></code> or <code class="computeroutput"><span class="identifier">nil_t</span></code>.
Using the <a href="../../../../../variant/index.html" target="_top">Boost.Variant</a>
@@ -100,8 +100,8 @@
</p>
<p>
In any event, both the discriminated-union or the single-element container
models serve as a conceptual ground for a class representing optional&#8212;i.e.
possibly uninitialized&#8212;objects. For instance, these models show the
models serve as a conceptual ground for a class representing optional—i.e.
possibly uninitialized—objects. For instance, these models show the
<span class="emphasis"><em>exact</em></span> semantics required for a wrapper of optional
values:
</p>
@@ -170,7 +170,7 @@
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright &#169; 2003-2007 Fernando Luis Cacciola Carballal<br>Copyright &#169; 2014-2018 Andrzej Krzemie&#324;ski<p>
<td align="right"><div class="copyright-footer">Copyright © 2003-2007 Fernando Luis Cacciola Carballal<br>Copyright © 2014-2018 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>)
</p>