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diff --git a/doc/html/boost/polymorphic_relaxed_get.html b/doc/html/boost/polymorphic_relaxed_get.html new file mode 100644 index 0000000000..f496b97a1c --- /dev/null +++ b/doc/html/boost/polymorphic_relaxed_get.html @@ -0,0 +1,128 @@ +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> +<title>Function polymorphic_relaxed_get</title> +<link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> +<meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> +<link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> +<link rel="up" href="../variant/reference.html#header.boost.variant.polymorphic_get_hpp" title="Header <boost/variant/polymorphic_get.hpp>"> +<link rel="prev" href="bad_polymorphic_get.html" title="Class bad_polymorphic_get"> +<link rel="next" href="polymorphic_strict_get.html" title="Function polymorphic_strict_get"> +</head> +<body bgcolor="white" text="black" 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href="polymorphic_strict_get.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +<div class="refentry"> +<a name="boost.polymorphic_relaxed_get"></a><div class="titlepage"></div> +<div class="refnamediv"> +<h2><span class="refentrytitle">Function polymorphic_relaxed_get</span></h2> +<p>boost::polymorphic_relaxed_get — Retrieves a value of a specified type from a given + <code class="computeroutput"><a class="link" href="variant.html" title="Class template variant">variant</a></code>.Unlike <a class="link" href="polymorphic_strict_get.html" title="Function polymorphic_strict_get">polymorphic_strict_get</a> does not assert at compile time + that type <code class="computeroutput">U</code> is one of the types that can be stored in variant.</p> +</div> +<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> +<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../variant/reference.html#header.boost.variant.polymorphic_get_hpp" title="Header <boost/variant/polymorphic_get.hpp>">boost/variant/polymorphic_get.hpp</a>> + +</span> +<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> U<span class="special">,</span> <span class="keyword">typename</span> T1<span class="special">,</span> <span class="keyword">typename</span> T2<span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="keyword">typename</span> TN<span class="special">></span> + <span class="identifier">U</span> <span class="special">*</span> <span class="identifier">polymorphic_relaxed_get</span><span class="special">(</span><a class="link" href="variant.html" title="Class template variant">variant</a><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">TN</span><span class="special">></span> <span class="special">*</span> operand<span class="special">)</span><span class="special">;</span> +<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> U<span class="special">,</span> <span class="keyword">typename</span> T1<span class="special">,</span> <span class="keyword">typename</span> T2<span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="keyword">typename</span> TN<span class="special">></span> + <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">*</span> <span class="identifier">polymorphic_relaxed_get</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="variant.html" title="Class template variant">variant</a><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">TN</span><span class="special">></span> <span class="special">*</span> operand<span class="special">)</span><span class="special">;</span> +<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> U<span class="special">,</span> <span class="keyword">typename</span> T1<span class="special">,</span> <span class="keyword">typename</span> T2<span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="keyword">typename</span> TN<span class="special">></span> + <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">polymorphic_relaxed_get</span><span class="special">(</span><a class="link" href="variant.html" title="Class template variant">variant</a><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">TN</span><span class="special">></span> <span class="special">&</span> operand<span class="special">)</span><span class="special">;</span> +<span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> U<span class="special">,</span> <span class="keyword">typename</span> T1<span class="special">,</span> <span class="keyword">typename</span> T2<span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="keyword">typename</span> TN<span class="special">></span> + <span class="keyword">const</span> <span class="identifier">U</span> <span class="special">&</span> <span class="identifier">polymorphic_relaxed_get</span><span class="special">(</span><span class="keyword">const</span> <a class="link" href="variant.html" title="Class template variant">variant</a><span class="special"><</span><span class="identifier">T1</span><span class="special">,</span> <span class="identifier">T2</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">TN</span><span class="special">></span> <span class="special">&</span> operand<span class="special">)</span><span class="special">;</span></pre></div> +<div class="refsect1"> +<a name="idp521174688"></a><h2>Description</h2> +<p>The <code class="computeroutput">polymorphic_get</code> function allows run-time checked, + type-safe retrieval of the content of the given + <code class="computeroutput"><a class="link" href="variant.html" title="Class template variant">variant</a></code>. The function succeeds + only if the content is of the specified type <code class="computeroutput">U</code> or of type + derived from type <code class="computeroutput">U</code>, with + failure indicated as described below.</p> +<p><span class="bold"><strong>Recomendation</strong></span>: Use + <code class="computeroutput"><a class="link" href="polymorphic_get.html" title="Function polymorphic_get">polymorphic_get</a></code> or <code class="computeroutput"><a class="link" href="polymorphic_strict_get.html" title="Function polymorphic_strict_get">polymorphic_strict_get</a></code> + in new code. + <code class="computeroutput"><a class="link" href="polymorphic_strict_get.html" title="Function polymorphic_strict_get">polymorphic_strict_get</a></code> + provides more compile time checks and it's behavior is closer to <code class="computeroutput">std::get</code> + from C++ Standard Library.</p> +<p><span class="bold"><strong>Warning</strong></span>: After either + <code class="computeroutput">operand</code> or its content is destroyed (e.g., when the + given <code class="computeroutput"><a class="link" href="variant.html" title="Class template variant">variant</a></code> is assigned a + value of different type), the returned reference is invalidated. + Thus, significant care and caution must be extended when handling + the returned reference.</p> +<div class="variablelist"><table border="0" class="variablelist compact"> +<colgroup> +<col align="left" valign="top"> +<col> +</colgroup> +<tbody> +<tr> +<td><p><span class="term">Notes:</span></p></td> +<td>As part of its guarantee of type-safety, <code class="computeroutput">polymorphic_get</code> + enforces <code class="computeroutput">const</code>-correctness. Thus, the specified type + <code class="computeroutput">U</code> must be <code class="computeroutput">const</code>-qualified whenever + <code class="computeroutput">operand</code> or its content is likewise + <code class="computeroutput">const</code>-qualified. The converse, however, is not required: + that is, the specified type <code class="computeroutput">U</code> may be + <code class="computeroutput">const</code>-qualified even when <code class="computeroutput">operand</code> and its + content are not.</td> +</tr> +<tr> +<td><p><span class="term">Returns:</span></p></td> +<td>If passed a pointer, <code class="computeroutput">polymorphic_get</code> returns a pointer to + the value content if it is of the specified type <code class="computeroutput">U</code> or of type + derived from type <code class="computeroutput">U</code>; + otherwise, a null pointer is returned. If passed a reference, + <code class="computeroutput">polymorphic_get</code> returns a reference to the value content if it is of + the specified type <code class="computeroutput">U</code> or of type + derived from type <code class="computeroutput">U</code>; otherwise, an exception is thrown + (see below).</td> +</tr> +<tr> +<td><p><span class="term">Throws:</span></p></td> +<td>Overloads taking a + <code class="computeroutput"><a class="link" href="variant.html" title="Class template variant">variant</a></code> pointer will not + throw; the overloads taking a + <code class="computeroutput"><a class="link" href="variant.html" title="Class template variant">variant</a></code> reference throw + <code class="computeroutput"><a class="link" href="bad_polymorphic_get.html" title="Class bad_polymorphic_get">bad_polymorphic_get</a></code> if the content is not of + the specified type <code class="computeroutput">U</code>or of type + derived from type <code class="computeroutput">U</code>.</td> +</tr> +<tr> +<td><p><span class="term">Rationale:</span></p></td> +<td>While visitation via + <code class="computeroutput"><a class="link" href="apply_visitor.html" title="Function apply_visitor">apply_visitor</a></code> + is generally preferred due to its greater safety, <code class="computeroutput">polymorphic_get</code> may + may be more convenient in some cases due to its straightforward + usage.</td> +</tr> +</tbody> +</table></div> +</div> +</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 © 2002, 2003 Eric Friedman, Itay Maman<p>Distributed under the Boost Software License, Version 1.0. + (See accompanying file <code class="filename">LICENSE_1_0.txt</code> 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> +</div></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="bad_polymorphic_get.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../variant/reference.html#header.boost.variant.polymorphic_get_hpp"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="polymorphic_strict_get.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +</body> +</html> |