ceph/src/boost/libs/scope_exit/doc/html/BOOST_SCOPE_EXIT_ALL.html

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  26 <a name="BOOST_SCOPE_EXIT_ALL"></a><div class="titlepage"></div>
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  28 <h2><span class="refentrytitle">Macro BOOST_SCOPE_EXIT_ALL</span></h2>
  29 <p>BOOST_SCOPE_EXIT_ALL &#8212; This macro declares a scope exit that captures all variables in scope (C++11 only). </p>
  30 </div>
  31 <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
  32 <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="reference.html#header.boost.scope_exit_hpp" title="Header &lt;boost/scope_exit.hpp&gt;">boost/scope_exit.hpp</a>&gt;
  33
  34 </span>BOOST_SCOPE_EXIT_ALL(capture_list)</pre></div>
  35 <div class="refsect1">
  36 <a name="id877356"></a><h2>Description</h2>
  37 <p>This macro accepts a capture list starting with either <code class="computeroutput">&amp;</code> or <code class="computeroutput">=</code> to capture all variables in scope by reference or value respectively (following the same syntax of C++11 lambdas). A part from that, this macro works like <code class="computeroutput"><a class="link" href="BOOST_SCOPE_EXIT.html" title="Macro BOOST_SCOPE_EXIT">BOOST_SCOPE_EXIT</a></code> (see <code class="computeroutput"><a class="link" href="BOOST_SCOPE_EXIT.html" title="Macro BOOST_SCOPE_EXIT">BOOST_SCOPE_EXIT</a></code> for more information):</p>
  38 <pre class="programlisting"><span class="special">{</span> <span class="comment">// Some local scope.</span>
  39     <span class="special">...</span>
  40     <span class="identifier">BOOST_SCOPE_EXIT_ALL</span><span class="special">(</span><span class="identifier">capture_list</span><span class="special">)</span> <span class="special">{</span> <span class="comment">// C++11 only.</span>
  41         <span class="special">...</span> <span class="comment">// Body code.</span>
  42     <span class="special">}</span><span class="special">;</span> <span class="comment">// Use `;` instead of `BOOST_SCOPE_EXIT_END` (C++11 only).</span>
  43     <span class="special">...</span>
  44 <span class="special">}</span>
  45 </pre>
  46 <p>Note how the end of the scope exit body declared by this macro must be marked by a semi-column <code class="computeroutput">;</code> (and not by <code class="computeroutput"><a class="link" href="BOOST_SCOPE_EXIT_END.html" title="Macro BOOST_SCOPE_EXIT_END">BOOST_SCOPE_EXIT_END</a></code>).</p>
  47 <p><span class="bold"><strong>Warning:</strong></span> This macro is only available on C++11 compilers (specifically, on C++11 compilers that do not define the Boost.Config <code class="computeroutput">BOOST_NO_CXX11_LAMBDAS</code> macro). It is not defined on non-C++11 compilers so its use on non-C++11 compilers will generate a compiler error.</p>
  48 <p><span class="bold"><strong>Parameters:</strong></span> </p>
  49 <div class="informaltable"><table class="table">
  50 <colgroup>
  51 <col>
  52 <col>
  53 </colgroup>
  54 <tbody><tr>
  55 <td><span class="bold"><strong><code class="computeroutput">capture_list</code></strong></span></td>
  56 <td>On compilers that support variadic macros (see also Boost.Config <code class="computeroutput">BOOST_NO_CXX11_VARIADIC_MACROS</code>), the capture list syntax is defined by the following grammar: <pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">capture_list</span><span class="special">:</span>
  57         <span class="identifier">capture_tuple</span> <span class="special">|</span> <span class="identifier">capture_sequence</span>
  58 <span class="identifier">capture_tuple</span><span class="special">:</span>
  59         <span class="special">{</span><span class="special">&amp;</span> <span class="special">|</span> <span class="special">=</span><span class="special">}</span> <span class="special">[</span><span class="special">,</span> <span class="identifier">capture</span><span class="special">,</span> <span class="identifier">capture</span><span class="special">,</span> <span class="special">...</span><span class="special">]</span>
  60 <span class="identifier">capture_sequence</span><span class="special">:</span>
  61         <span class="special">{</span><span class="special">(</span><span class="special">&amp;</span><span class="special">)</span> <span class="special">|</span> <span class="special">(</span><span class="special">=</span><span class="special">)</span><span class="special">}</span> <span class="special">[</span><span class="special">(</span><span class="identifier">capture</span><span class="special">)</span> <span class="special">(</span><span class="identifier">capture</span><span class="special">)</span> <span class="special">...</span><span class="special">]</span>
  62 <span class="identifier">capture</span><span class="special">:</span>
  63         <span class="special">[</span><span class="special">&amp;</span><span class="special">]</span><span class="identifier">variable</span> <span class="special">|</span> <span class="identifier">this_</span>
  64 </pre> On compilers that do not support variadic macros, <code class="computeroutput">capture_tuple</code> cannot be used: <pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">capture_list</span><span class="special">:</span>
  65         <span class="keyword">void</span> <span class="special">|</span> <span class="identifier">capture_sequence</span>
  66 </pre> Furthermore, on C++11 compilers that support the use of <code class="computeroutput">typename</code> outside templates, also <code class="computeroutput">this</code> can be used to capture the object at member function scope: <pre xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="table-programlisting"><span class="identifier">capture</span><span class="special">:</span>
  67         <span class="special">[</span><span class="special">&amp;</span><span class="special">]</span><span class="identifier">variable</span> <span class="special">|</span> <span class="identifier">this_</span> <span class="special">|</span> <span class="keyword">this</span>
  68 </pre>(Lexical conventions: <code class="computeroutput">token1 | token2</code> means either <code class="computeroutput">token1</code> or <code class="computeroutput">token2</code>; <code class="computeroutput">[token]</code> means either <code class="computeroutput">token</code> or nothing; <code class="computeroutput">{expression}</code> means the token resulting from the expression.)  </td>
  69 </tr></tbody>
  70 </table></div>
  71 <p>
  72 </p>
  73 <p>Note that on compilers with variadic macro support (which should be all C++11 compilers), the capture list can be specified as a comma-separated list. On all compilers, the same macro <code class="computeroutput"><a class="link" href="BOOST_SCOPE_EXIT_ALL.html" title="Macro BOOST_SCOPE_EXIT_ALL">BOOST_SCOPE_EXIT_ALL</a></code> also allows to specify the capture list as a Boost.Preprocessor sequence.</p>
  74 <p>The capture list must always contain at least the leading <code class="computeroutput">&amp;</code> or <code class="computeroutput">=</code> so it can never be <code class="computeroutput">void</code> (<code class="computeroutput">BOOST_SCOPE_EXIT(void)</code> should be used to program scope exits with an empty capture list).</p>
  75 <p>In general, the special macro <code class="computeroutput"><a class="link" href="BOOST_SCOPE_EXIT_ALL_ID.html" title="Macro BOOST_SCOPE_EXIT_ALL_ID">BOOST_SCOPE_EXIT_ALL_ID</a></code> must be used instead of <code class="computeroutput"><a class="link" href="BOOST_SCOPE_EXIT_ALL.html" title="Macro BOOST_SCOPE_EXIT_ALL">BOOST_SCOPE_EXIT_ALL</a></code> when it is necessary to expand multiple scope exit declarations on the same line.</p>
  76 <p><span class="bold"><strong>Warning:</strong></span> This macro capture list follows the exact same syntax of C++11 lambda captures which is unfortunately different from the syntax of  <code class="computeroutput"><a class="link" href="BOOST_SCOPE_EXIT.html" title="Macro BOOST_SCOPE_EXIT">BOOST_SCOPE_EXIT</a></code> captures (unless programmers define the  <code class="computeroutput"><a class="link" href="BOOST_SCOPE_EXIT_CONFIG_USE_LAMBDAS.html" title="Macro BOOST_SCOPE_EXIT_CONFIG_USE_LAMBDAS">BOOST_SCOPE_EXIT_CONFIG_USE_LAMBDAS</a></code> macro). For example, like C++11 lambda functions, <code class="computeroutput"><a class="link" href="BOOST_SCOPE_EXIT_ALL.html" title="Macro BOOST_SCOPE_EXIT_ALL">BOOST_SCOPE_EXIT_ALL</a></code> requires to capture data members by capturing the object <code class="computeroutput">this</code> while  <code class="computeroutput"><a class="link" href="BOOST_SCOPE_EXIT.html" title="Macro BOOST_SCOPE_EXIT">BOOST_SCOPE_EXIT</a></code> allows to capture data members directly and without capturing the object.</p>
  77 <p><span class="bold"><strong>Warning:</strong></span> The implementation executes the scope exit body within a destructor thus the scope exit body must never throw in order to comply with STL exception safety requirements.</p>
  78 <p><span class="bold"><strong>Note:</strong></span> This macro can always be used also within templates (so there is no need for a <code class="computeroutput">BOOST_SCOPE_EXIT_ALL_TPL</code> macro).</p>
  79 <p><span class="bold"><strong>See:</strong></span> <a class="link" href="scope_exit/tutorial.html" title="Tutorial"> Tutorial</a> section,  <a class="link" href="scope_exit/no_variadic_macros.html" title="Annex: No Variadic Macros"> No Variadic Macros</a> section,  <code class="computeroutput"><a class="link" href="BOOST_SCOPE_EXIT.html" title="Macro BOOST_SCOPE_EXIT">BOOST_SCOPE_EXIT</a></code>, <code class="computeroutput"><a class="link" href="BOOST_SCOPE_EXIT_ALL_ID.html" title="Macro BOOST_SCOPE_EXIT_ALL_ID">BOOST_SCOPE_EXIT_ALL_ID</a></code>. </p>
  80 </div>
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  83 <td align="left"></td>
  84 <td align="right"><div class="copyright-footer">Copyright &#169; 2006-2012 Alexander Nasonov, Lorenzo Caminiti<p>
  85         Distributed under the Boost Software License, Version 1.0 (see accompanying
  86         file LICENSE_1_0.txt or a copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
  87       </p>
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