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diff --git a/doc/html/thread/emulations.html b/doc/html/thread/emulations.html new file mode 100644 index 0000000000..9bc311ccfa --- /dev/null +++ b/doc/html/thread/emulations.html @@ -0,0 +1,611 @@ +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> +<title>Emulations</title> +<link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css"> +<meta name="generator" content="DocBook XSL Stylesheets V1.76.1"> +<link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> +<link rel="up" href="../thread.html" title="Chapter 28. Thread 3.0.1"> +<link rel="prev" href="time.html" title="Time Requirements"> +<link rel="next" href="acknowledgements.html" title="Acknowledgments"> +</head> +<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> +<table cellpadding="2" width="100%"><tr> +<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td> +<td align="center"><a href="../../../index.html">Home</a></td> +<td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td> +<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> +<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> +<td align="center"><a href="../../../more/index.htm">More</a></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="time.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../thread.html"><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="acknowledgements.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +<div class="section"> +<div class="titlepage"><div><div><h2 class="title" style="clear: both"> +<a name="thread.emulations"></a><a class="link" href="emulations.html" title="Emulations">Emulations</a> +</h2></div></div></div> +<div class="toc"><dl> +<dt><span class="section"><a href="emulations.html#thread.emulations.delete"><code class="computeroutput"><span class="special">=</span><span class="keyword">delete</span></code> emulation</a></span></dt> +<dt><span class="section"><a href="emulations.html#thread.emulations.move">Move semantics</a></span></dt> +<dt><span class="section"><a href="emulations.html#thread.emulations.bool_explicit_conversion">Bool explicit + conversion</a></span></dt> +<dt><span class="section"><a href="emulations.html#thread.emulations.scoped_enums">Scoped Enums</a></span></dt> +</dl></div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="thread.emulations.delete"></a><a class="link" href="emulations.html#thread.emulations.delete" title="=delete emulation"><code class="computeroutput"><span class="special">=</span><span class="keyword">delete</span></code> emulation</a> +</h3></div></div></div> +<p> + C++11 allows to delete some implicitly generated functions as constructors + and assignment using '= delete' as in + </p> +<pre class="programlisting"><span class="keyword">public</span><span class="special">:</span> + <span class="identifier">thread</span><span class="special">(</span><span class="identifier">thread</span> <span class="keyword">const</span><span class="special">&)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span> +</pre> +<p> + On compilers not supporting this feature, Boost.Thread relays on a partial + simulation, it declares the function as private without definition. + </p> +<pre class="programlisting"><span class="keyword">private</span><span class="special">:</span> + <span class="identifier">thread</span><span class="special">(</span><span class="identifier">thread</span> <span class="special">&);</span> +</pre> +<p> + The emulation is partial as the private function can be used for overload + resolution for some compilers and prefer it to other overloads that need + a conversion. See below the consequences on the move semantic emulation. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="thread.emulations.move"></a><a class="link" href="emulations.html#thread.emulations.move" title="Move semantics">Move semantics</a> +</h3></div></div></div> +<div class="toc"><dl> +<dt><span class="section"><a href="emulations.html#thread.emulations.move.deprecated">Deprecated Version + 2 interface</a></span></dt> +<dt><span class="section"><a href="emulations.html#thread.emulations.move.portable">Portable interface</a></span></dt> +</dl></div> +<p> + In order to implement Movable classes, move parameters and return types Boost.Thread + uses the rvalue reference when the compiler support it. On compilers not + supporting it Boost.Thread uses either the emulation provided by Boost.Move + or the emulation provided by the previous versions of Boost.Thread depending + whether <code class="computeroutput"><span class="identifier">BOOST_THREAD_USES_MOVE</span></code> + is defined or not. This macros is unset by default when <code class="computeroutput"><span class="identifier">BOOST_THREAD_VERSION</span></code> + is 2. Since <code class="computeroutput"><span class="identifier">BOOST_THREAD_VERSION</span></code> + 3, <code class="computeroutput"><span class="identifier">BOOST_THREAD_USES_MOVE</span></code> + is defined. + </p> +<div class="section"> +<div class="titlepage"><div><div><h4 class="title"> +<a name="thread.emulations.move.deprecated"></a><a class="link" href="emulations.html#thread.emulations.move.deprecated" title="Deprecated Version 2 interface">Deprecated Version + 2 interface</a> +</h4></div></div></div> +<div class="toc"><dl> +<dt><span class="section"><a href="emulations.html#thread.emulations.move.deprecated.Helper">Helpers + class and function</a></span></dt> +<dt><span class="section"><a href="emulations.html#thread.emulations.move.deprecated.movable">Movable + emulation</a></span></dt> +</dl></div> +<p> + Previous to version 1.50, Boost.Thread make use of its own move semantic + emulation which had more limitations than the provided by Boost.Move. In + addition, it is of interest of the whole Boost community that Boost.Thread + uses Boost.Move so that boost::thread can be stored on Movable aware containers. + </p> +<p> + To preserve backward compatibility at least during some releases, Boost.Thread + allows the user to use the deprecated move semantic emulation defining + BOOST_THREAD_DONT_USE_MOVE. + </p> +<p> + Many aspects of move semantics can be emulated for compilers not supporting + rvalue references and Boost.Thread legacy offers tools for that purpose. + </p> +<div class="section"> +<div class="titlepage"><div><div><h5 class="title"> +<a name="thread.emulations.move.deprecated.Helper"></a><a class="link" href="emulations.html#thread.emulations.move.deprecated.Helper" title="Helpers class and function">Helpers + class and function</a> +</h5></div></div></div> +<p> + Next follows the interface of the legacy move semantic helper class and + function. + </p> +<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span> +<span class="special">{</span> + <span class="keyword">namespace</span> <span class="identifier">detail</span> + <span class="special">{</span> + <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">></span> + <span class="keyword">struct</span> <span class="identifier">thread_move_t</span> + <span class="special">{</span> + <span class="keyword">explicit</span> <span class="identifier">thread_move_t</span><span class="special">(</span><span class="identifier">T</span><span class="special">&</span> <span class="identifier">t_</span><span class="special">);</span> + <span class="identifier">T</span><span class="special">&</span> <span class="keyword">operator</span><span class="special">*()</span> <span class="keyword">const</span><span class="special">;</span> + <span class="identifier">T</span><span class="special">*</span> <span class="keyword">operator</span><span class="special">->()</span> <span class="keyword">const</span><span class="special">;</span> + <span class="keyword">private</span><span class="special">:</span> + <span class="keyword">void</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">thread_move_t</span><span class="special">&);</span> + <span class="special">};</span> + <span class="special">}</span> + <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">></span> + <span class="identifier">boost</span><span class="special">::</span><span class="identifier">detail</span><span class="special">::</span><span class="identifier">thread_move_t</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="identifier">move</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">detail</span><span class="special">::</span><span class="identifier">thread_move_t</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="identifier">t</span><span class="special">);</span> +<span class="special">}</span> +</pre> +</div> +<div class="section"> +<div class="titlepage"><div><div><h5 class="title"> +<a name="thread.emulations.move.deprecated.movable"></a><a class="link" href="emulations.html#thread.emulations.move.deprecated.movable" title="Movable emulation">Movable + emulation</a> +</h5></div></div></div> +<p> + We can write a MovableOny class as follows. You just need to follow these + simple steps: + </p> +<div class="itemizedlist"><ul class="itemizedlist" type="disc"> +<li class="listitem"> + Add a conversion to the <code class="computeroutput"><span class="identifier">detail</span><span class="special">::</span><span class="identifier">thread_move_t</span><span class="special"><</span><span class="identifier">classname</span><span class="special">></span></code> + </li> +<li class="listitem"> + Make the copy constructor private. + </li> +<li class="listitem"> + Write a constructor taking the parameter as <code class="computeroutput"><span class="identifier">detail</span><span class="special">::</span><span class="identifier">thread_move_t</span><span class="special"><</span><span class="identifier">classname</span><span class="special">></span></code> + </li> +<li class="listitem"> + Write an assignment taking the parameter as <code class="computeroutput"><span class="identifier">detail</span><span class="special">::</span><span class="identifier">thread_move_t</span><span class="special"><</span><span class="identifier">classname</span><span class="special">></span></code> + </li> +</ul></div> +<p> + For example the thread class defines the following: + </p> +<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">thread</span> +<span class="special">{</span> + <span class="comment">// ...</span> +<span class="keyword">private</span><span class="special">:</span> + <span class="identifier">thread</span><span class="special">(</span><span class="identifier">thread</span><span class="special">&);</span> + <span class="identifier">thread</span><span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">thread</span><span class="special">&);</span> +<span class="keyword">public</span><span class="special">:</span> + <span class="identifier">detail</span><span class="special">::</span><span class="identifier">thread_move_t</span><span class="special"><</span><span class="identifier">thread</span><span class="special">></span> <span class="identifier">move</span><span class="special">()</span> + <span class="special">{</span> + <span class="identifier">detail</span><span class="special">::</span><span class="identifier">thread_move_t</span><span class="special"><</span><span class="identifier">thread</span><span class="special">></span> <span class="identifier">x</span><span class="special">(*</span><span class="keyword">this</span><span class="special">);</span> + <span class="keyword">return</span> <span class="identifier">x</span><span class="special">;</span> + <span class="special">}</span> + <span class="keyword">operator</span> <span class="identifier">detail</span><span class="special">::</span><span class="identifier">thread_move_t</span><span class="special"><</span><span class="identifier">thread</span><span class="special">>()</span> + <span class="special">{</span> + <span class="keyword">return</span> <span class="identifier">move</span><span class="special">();</span> + <span class="special">}</span> + <span class="identifier">thread</span><span class="special">(</span><span class="identifier">detail</span><span class="special">::</span><span class="identifier">thread_move_t</span><span class="special"><</span><span class="identifier">thread</span><span class="special">></span> <span class="identifier">x</span><span class="special">)</span> + <span class="special">{</span> + <span class="identifier">thread_info</span><span class="special">=</span><span class="identifier">x</span><span class="special">-></span><span class="identifier">thread_info</span><span class="special">;</span> + <span class="identifier">x</span><span class="special">-></span><span class="identifier">thread_info</span><span class="special">.</span><span class="identifier">reset</span><span class="special">();</span> + <span class="special">}</span> + <span class="identifier">thread</span><span class="special">&</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">detail</span><span class="special">::</span><span class="identifier">thread_move_t</span><span class="special"><</span><span class="identifier">thread</span><span class="special">></span> <span class="identifier">x</span><span class="special">)</span> + <span class="special">{</span> + <span class="identifier">thread</span> <span class="identifier">new_thread</span><span class="special">(</span><span class="identifier">x</span><span class="special">);</span> + <span class="identifier">swap</span><span class="special">(</span><span class="identifier">new_thread</span><span class="special">);</span> + <span class="keyword">return</span> <span class="special">*</span><span class="keyword">this</span><span class="special">;</span> + <span class="special">}</span> + <span class="comment">// ...</span> + +<span class="special">};</span> +</pre> +</div> +</div> +<div class="section"> +<div class="titlepage"><div><div><h4 class="title"> +<a name="thread.emulations.move.portable"></a><a class="link" href="emulations.html#thread.emulations.move.portable" title="Portable interface">Portable interface</a> +</h4></div></div></div> +<div class="toc"><dl> +<dt><span class="section"><a href="emulations.html#thread.emulations.move.portable.NO_COPYABLE"><code class="computeroutput"><span class="identifier">BOOST_THREAD_NO_COPYABLE</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code></a></span></dt> +<dt><span class="section"><a href="emulations.html#thread.emulations.move.portable.MOVABLE"><code class="computeroutput"><span class="identifier">BOOST_THREAD_MOVABLE</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code></a></span></dt> +<dt><span class="section"><a href="emulations.html#thread.emulations.move.portable.MOVABLE_ONLY"><code class="computeroutput"><span class="identifier">BOOST_THREAD_MOVABLE_ONLY</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code></a></span></dt> +<dt><span class="section"><a href="emulations.html#thread.emulations.move.portable.COPYABLE_AND_MOVABLE"><code class="computeroutput"><span class="identifier">BOOST_THREAD_COPYABLE_AND_MOVABLE</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code></a></span></dt> +<dt><span class="section"><a href="emulations.html#thread.emulations.move.portable.RV_REF"><code class="computeroutput"><span class="identifier">BOOST_THREAD_RV_REF</span><span class="special">(</span><span class="identifier">TYPE</span><span class="special">)</span></code>, + <code class="computeroutput"><span class="identifier">BOOST_THREAD_RV_REF_BEG</span></code> + and <code class="computeroutput"><span class="identifier">BOOST_THREAD_RV_REF_END</span></code></a></span></dt> +<dt><span class="section"><a href="emulations.html#thread.emulations.move.portable.RV"><code class="computeroutput"><span class="identifier">BOOST_THREAD_RV</span><span class="special">(</span><span class="identifier">V</span><span class="special">)</span></code></a></span></dt> +<dt><span class="section"><a href="emulations.html#thread.emulations.move.portable.MAKE_RV_REF"><code class="computeroutput"><span class="identifier">BOOST_THREAD_MAKE_RV_REF</span><span class="special">(</span><span class="identifier">RVALUE</span><span class="special">)</span></code></a></span></dt> +<dt><span class="section"><a href="emulations.html#thread.emulations.move.portable.DCL_MOVABLE"><code class="computeroutput"><span class="identifier">BOOST_THREAD_DCL_MOVABLE</span></code>, <code class="computeroutput"><span class="identifier">BOOST_THREAD_DCL_MOVABLE_BEG</span><span class="special">(</span><span class="identifier">T1</span><span class="special">)</span></code> and + <code class="computeroutput"><span class="identifier">BOOST_THREAD_DCL_MOVABLE_END</span></code></a></span></dt> +</dl></div> +<p> + In order to make the library code portable Boost.Thread uses some macros + that will use either the ones provided by Boost.Move or the deprecated + move semantics provided by previous versions of Boost.Thread. + </p> +<p> + See the Boost.Move documentation for a complete description on how to declare + new Movable classes and its limitations. + </p> +<div class="itemizedlist"><ul class="itemizedlist" type="disc"> +<li class="listitem"> + <code class="computeroutput"><span class="identifier">BOOST_THREAD_RV_REF</span><span class="special">(</span><span class="identifier">TYPE</span><span class="special">)</span></code> is the equivalent of <code class="computeroutput"><span class="identifier">BOOST_RV_REF</span><span class="special">(</span><span class="identifier">TYPE</span><span class="special">)</span></code> + </li> +<li class="listitem"> + <code class="computeroutput"><span class="identifier">BOOST_THREAD_RV_REF_BEG</span></code> + is the equivalent of <code class="computeroutput"><span class="identifier">BOOST_RV_REF_BEG</span><span class="special">(</span><span class="identifier">TYPE</span><span class="special">)</span></code> + </li> +<li class="listitem"> + <code class="computeroutput"><span class="identifier">BOOST_THREAD_RV_REF_END</span></code> + is the equivalent of <code class="computeroutput"><span class="identifier">BOOST_RV_REF_END</span><span class="special">(</span><span class="identifier">TYPE</span><span class="special">)</span></code> + </li> +<li class="listitem"> + <code class="computeroutput"><span class="identifier">BOOST_THREAD_FWD_REF</span><span class="special">(</span><span class="identifier">TYPE</span><span class="special">)</span></code> is the equivalent of `BOOST_FWD_REF(TYPE) + </li> +</ul></div> +<p> + In addition the following macros are needed to make the code portable: + </p> +<div class="itemizedlist"><ul class="itemizedlist" type="disc"> +<li class="listitem"> + <code class="computeroutput"><span class="identifier">BOOST_THREAD_RV</span><span class="special">(</span><span class="identifier">V</span><span class="special">)</span></code> + macro to access the rvalue from a BOOST_THREAD_RV_REF(TYPE), + </li> +<li class="listitem"> + <code class="computeroutput"><span class="identifier">BOOST_THREAD_MAKE_RV_REF</span><span class="special">(</span><span class="identifier">RVALUE</span><span class="special">)</span></code> makes a rvalue. + </li> +<li class="listitem"> + <code class="computeroutput"><span class="identifier">BOOST_THREAD_DCL_MOVABLE</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code> to avoid conflicts with Boost.Move + </li> +<li class="listitem"> + <code class="computeroutput"><span class="identifier">BOOST_THREAD_DCL_MOVABLE_BEG</span><span class="special">(</span><span class="identifier">T1</span><span class="special">)</span></code> and <code class="computeroutput"><span class="identifier">BOOST_THREAD_DCL_MOVABLE_END</span></code> + are variant of <code class="computeroutput"><span class="identifier">BOOST_THREAD_DCL_MOVABLE</span></code> + when the parameter is a template instantiation. + </li> +</ul></div> +<p> + Other macros are provided and must be included on the public section: + </p> +<div class="itemizedlist"><ul class="itemizedlist" type="disc"> +<li class="listitem"> + <code class="computeroutput"><span class="identifier">BOOST_THREAD_NO_COPYABLE</span></code> + declares a class no-copyable either deleting the copy constructors + and copy assignment or moving them to the private section. + </li> +<li class="listitem"> + <code class="computeroutput"><span class="identifier">BOOST_THREAD_MOVABLE</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code> declares all the implicit conversions + to an rvalue-reference. + </li> +<li class="listitem"> + <code class="computeroutput"><span class="identifier">BOOST_THREAD_MOVABLE_ONLY</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code> is the equivalent of <code class="computeroutput"><span class="identifier">BOOST_MOVABLE_BUT_NOT_COPYABLE</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code> + </li> +<li class="listitem"> + <code class="computeroutput"><span class="identifier">BOOST_THREAD_COPYABLE_AND_MOVABLE</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code> is the equivalent of <code class="computeroutput"><span class="identifier">BOOST_COPYABLE_AND_MOVABLE</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code> + </li> +</ul></div> +<div class="section"> +<div class="titlepage"><div><div><h5 class="title"> +<a name="thread.emulations.move.portable.NO_COPYABLE"></a><a class="link" href="emulations.html#thread.emulations.move.portable.NO_COPYABLE" title="BOOST_THREAD_NO_COPYABLE(CLASS)"><code class="computeroutput"><span class="identifier">BOOST_THREAD_NO_COPYABLE</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code></a> +</h5></div></div></div> +<p> + This macro marks a class as no copyable, disabling copy construction + and assignment. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h5 class="title"> +<a name="thread.emulations.move.portable.MOVABLE"></a><a class="link" href="emulations.html#thread.emulations.move.portable.MOVABLE" title="BOOST_THREAD_MOVABLE(CLASS)"><code class="computeroutput"><span class="identifier">BOOST_THREAD_MOVABLE</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code></a> +</h5></div></div></div> +<p> + This macro marks a class as movable, declaring all the implicit conversions + to an rvalue-reference. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h5 class="title"> +<a name="thread.emulations.move.portable.MOVABLE_ONLY"></a><a class="link" href="emulations.html#thread.emulations.move.portable.MOVABLE_ONLY" title="BOOST_THREAD_MOVABLE_ONLY(CLASS)"><code class="computeroutput"><span class="identifier">BOOST_THREAD_MOVABLE_ONLY</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code></a> +</h5></div></div></div> +<p> + This macro marks a type as movable but not copyable, disabling copy construction + and assignment. The user will need to write a move constructor/assignment + to fully write a movable but not copyable class. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h5 class="title"> +<a name="thread.emulations.move.portable.COPYABLE_AND_MOVABLE"></a><a class="link" href="emulations.html#thread.emulations.move.portable.COPYABLE_AND_MOVABLE" title="BOOST_THREAD_COPYABLE_AND_MOVABLE(CLASS)"><code class="computeroutput"><span class="identifier">BOOST_THREAD_COPYABLE_AND_MOVABLE</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code></a> +</h5></div></div></div> +<p> + This macro marks a type as copyable and movable. The user will need to + write a move constructor/assignment and a copy assignment to fully write + a copyable and movable class. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h5 class="title"> +<a name="thread.emulations.move.portable.RV_REF"></a><a class="link" href="emulations.html#thread.emulations.move.portable.RV_REF" title="BOOST_THREAD_RV_REF(TYPE), BOOST_THREAD_RV_REF_BEG and BOOST_THREAD_RV_REF_END"><code class="computeroutput"><span class="identifier">BOOST_THREAD_RV_REF</span><span class="special">(</span><span class="identifier">TYPE</span><span class="special">)</span></code>, + <code class="computeroutput"><span class="identifier">BOOST_THREAD_RV_REF_BEG</span></code> + and <code class="computeroutput"><span class="identifier">BOOST_THREAD_RV_REF_END</span></code></a> +</h5></div></div></div> +<p> + This macro is used to achieve portable syntax in move constructors and + assignments for classes marked as <code class="computeroutput"><span class="identifier">BOOST_THREAD_COPYABLE_AND_MOVABLE</span></code> + or <code class="computeroutput"><span class="identifier">BOOST_THREAD_MOVABLE_ONLY</span></code>. + </p> +<p> + <code class="computeroutput"><span class="identifier">BOOST_THREAD_RV_REF_BEG</span></code> + and <code class="computeroutput"><span class="identifier">BOOST_THREAD_RV_REF_END</span></code> + are used when the parameter end with a <code class="computeroutput"><span class="special">></span></code> + to avoid the compiler error. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h5 class="title"> +<a name="thread.emulations.move.portable.RV"></a><a class="link" href="emulations.html#thread.emulations.move.portable.RV" title="BOOST_THREAD_RV(V)"><code class="computeroutput"><span class="identifier">BOOST_THREAD_RV</span><span class="special">(</span><span class="identifier">V</span><span class="special">)</span></code></a> +</h5></div></div></div> +<p> + While Boost.Move emulation allows to access an rvalue reference <code class="computeroutput"><span class="identifier">BOOST_THREAD_RV_REF</span><span class="special">(</span><span class="identifier">TYPE</span><span class="special">)</span></code> + using the dot operator, the legacy defines the <code class="computeroutput"><span class="keyword">operator</span><span class="special">-></span></code>. We need then a macro <code class="computeroutput"><span class="identifier">BOOST_THREAD_RV</span></code> that mask this difference. + E.g. + </p> +<pre class="programlisting"><span class="identifier">thread</span><span class="special">(</span><span class="identifier">BOOST_THREAD_RV_REF</span><span class="special">(</span><span class="identifier">thread</span><span class="special">)</span> <span class="identifier">x</span><span class="special">)</span> +<span class="special">{</span> + <span class="identifier">thread_info</span><span class="special">=</span><span class="identifier">BOOST_THREAD_RV</span><span class="special">(</span><span class="identifier">x</span><span class="special">).</span><span class="identifier">thread_info</span><span class="special">;</span> + <span class="identifier">BOOST_THREAD_RV</span><span class="special">(</span><span class="identifier">x</span><span class="special">).</span><span class="identifier">thread_info</span><span class="special">.</span><span class="identifier">reset</span><span class="special">();</span> +<span class="special">}</span> +</pre> +<p> + The use of this macros has reduced considerably the size of the Boost.Thread + move related code. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h5 class="title"> +<a name="thread.emulations.move.portable.MAKE_RV_REF"></a><a class="link" href="emulations.html#thread.emulations.move.portable.MAKE_RV_REF" title="BOOST_THREAD_MAKE_RV_REF(RVALUE)"><code class="computeroutput"><span class="identifier">BOOST_THREAD_MAKE_RV_REF</span><span class="special">(</span><span class="identifier">RVALUE</span><span class="special">)</span></code></a> +</h5></div></div></div> +<p> + While Boost.Move is the best C++03 move emulation there are some limitations + that impact the way the library can be used. For example, with the following + declarations + </p> +<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">thread</span> <span class="special">{</span> + <span class="comment">// ...</span> +<span class="keyword">private</span><span class="special">:</span> + <span class="identifier">thread</span><span class="special">(</span><span class="identifier">thread</span> <span class="special">&);</span> +<span class="keyword">public</span><span class="special">:</span> + <span class="identifier">thread</span><span class="special">(</span><span class="identifier">rv</span><span class="special"><</span><span class="identifier">thread</span><span class="special">>&);</span> + <span class="comment">// ...</span> +<span class="special">};</span> +</pre> +<p> + This could not work on some compilers even if thread is convertible to + <code class="computeroutput"><span class="identifier">rv</span><span class="special"><</span><span class="identifier">thread</span><span class="special">></span></code> + because the compiler prefers the private copy constructor. + </p> +<pre class="programlisting"><span class="identifier">thread</span> <span class="identifier">mkth</span><span class="special">()</span> +<span class="special">{</span> + <span class="keyword">return</span> <span class="identifier">thread</span><span class="special">(</span><span class="identifier">f</span><span class="special">);</span> +<span class="special">}</span> +</pre> +<p> + On these compilers we need to use instead an explicit conversion. The + library provides a move member function that allows to workaround the + issue. + </p> +<pre class="programlisting"><span class="identifier">thread</span> <span class="identifier">mkth</span><span class="special">()</span> +<span class="special">{</span> + <span class="keyword">return</span> <span class="identifier">thread</span><span class="special">(</span><span class="identifier">f</span><span class="special">).</span><span class="identifier">move</span><span class="special">();</span> +<span class="special">}</span> +</pre> +<p> + Note that <code class="computeroutput"><span class="special">::</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">move</span></code> + can not be used in this case as thread is not implicitly convertible + to <code class="computeroutput"><span class="identifier">thread</span><span class="special">&</span></code>. + </p> +<pre class="programlisting"><span class="identifier">thread</span> <span class="identifier">mkth</span><span class="special">()</span> +<span class="special">{</span> + <span class="keyword">return</span> <span class="special">::</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">thread</span><span class="special">(</span><span class="identifier">f</span><span class="special">));</span> +<span class="special">}</span> +</pre> +<p> + To make the code portable Boost.Thread the user needs to use a macro + <code class="computeroutput"><span class="identifier">BOOST_THREAD_MAKE_RV_REF</span></code> + that can be used as in + </p> +<pre class="programlisting"><span class="identifier">thread</span> <span class="identifier">mkth</span><span class="special">()</span> +<span class="special">{</span> + <span class="keyword">return</span> <span class="identifier">BOOST_THREAD_MAKE_RV_REF</span><span class="special">(</span><span class="identifier">thread</span><span class="special">(</span><span class="identifier">f</span><span class="special">));</span> +<span class="special">}</span> +</pre> +<p> + Note that this limitation is shared also by the legacy Boost.Thread move + emulation. + </p> +</div> +<div class="section"> +<div class="titlepage"><div><div><h5 class="title"> +<a name="thread.emulations.move.portable.DCL_MOVABLE"></a><a class="link" href="emulations.html#thread.emulations.move.portable.DCL_MOVABLE" title="BOOST_THREAD_DCL_MOVABLE, BOOST_THREAD_DCL_MOVABLE_BEG(T1) and BOOST_THREAD_DCL_MOVABLE_END"><code class="computeroutput"><span class="identifier">BOOST_THREAD_DCL_MOVABLE</span></code>, <code class="computeroutput"><span class="identifier">BOOST_THREAD_DCL_MOVABLE_BEG</span><span class="special">(</span><span class="identifier">T1</span><span class="special">)</span></code> and + <code class="computeroutput"><span class="identifier">BOOST_THREAD_DCL_MOVABLE_END</span></code></a> +</h5></div></div></div> +<p> + As Boost.Move defines also the <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">move</span></code> + function we need to specialize the <code class="computeroutput"><span class="identifier">has_move_emulation_enabled_aux</span></code> + metafunction. + </p> +<pre class="programlisting"><span class="keyword">template</span> <span class="special"><></span> +<span class="keyword">struct</span> <span class="identifier">has_move_emulation_enabled_aux</span><span class="special"><</span><span class="identifier">thread</span><span class="special">></span> + <span class="special">:</span> <span class="identifier">BOOST_MOVE_BOOST_NS</span><span class="special">::</span><span class="identifier">integral_constant</span><span class="special"><</span><span class="keyword">bool</span><span class="special">,</span> <span class="keyword">true</span><span class="special">></span> +<span class="special">{};</span> +</pre> +<p> + so that the following Boost.Move overload is disabled + </p> +<pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">></span> +<span class="keyword">inline</span> <span class="keyword">typename</span> <span class="identifier">BOOST_MOVE_BOOST_NS</span><span class="special">::</span><span class="identifier">disable_if</span><span class="special"><</span><span class="identifier">has_move_emulation_enabled_aux</span><span class="special"><</span><span class="identifier">T</span><span class="special">>,</span> <span class="identifier">T</span><span class="special">&>::</span><span class="identifier">type</span> <span class="identifier">move</span><span class="special">(</span><span class="identifier">T</span><span class="special">&</span> <span class="identifier">x</span><span class="special">);</span> +</pre> +<p> + The macros <code class="computeroutput"><span class="identifier">BOOST_THREAD_DCL_MOVABLE</span><span class="special">(</span><span class="identifier">CLASS</span><span class="special">)</span></code>, <code class="computeroutput"><span class="identifier">BOOST_THREAD_DCL_MOVABLE_BEG</span><span class="special">(</span><span class="identifier">T1</span><span class="special">)</span></code> and <code class="computeroutput"><span class="identifier">BOOST_THREAD_DCL_MOVABLE_END</span></code> + are used for this purpose. E.g. + </p> +<pre class="programlisting"><span class="identifier">BOOST_THREAD_DCL_MOVABLE</span><span class="special">(</span><span class="identifier">thread</span><span class="special">)</span> +</pre> +<p> + and + </p> +<pre class="programlisting"><span class="identifier">BOOST_THREAD_DCL_MOVABLE_BEG</span><span class="special">(</span><span class="identifier">T</span><span class="special">)</span> <span class="identifier">promise</span><span class="special"><</span><span class="identifier">T</span><span class="special">></span> <span class="identifier">BOOST_THREAD_DCL_MOVABLE_END</span> +</pre> +</div> +</div> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="thread.emulations.bool_explicit_conversion"></a><a class="link" href="emulations.html#thread.emulations.bool_explicit_conversion" title="Bool explicit conversion">Bool explicit + conversion</a> +</h3></div></div></div> +<div class="toc"><dl> +<dt><span class="section"><a href="emulations.html#thread.emulations.bool_explicit_conversion.bool_conversion"><code class="computeroutput"><span class="keyword">operator</span> </code><span class="emphasis"><em>unspecified-bool-type</em></span><code class="computeroutput"><span class="special">()</span> <span class="keyword">const</span></code></a></span></dt> +<dt><span class="section"><a href="emulations.html#thread.emulations.bool_explicit_conversion.operator_not"><code class="computeroutput"><span class="keyword">bool</span> <span class="keyword">operator</span><span class="special">!()</span> <span class="keyword">const</span></code></a></span></dt> +</dl></div> +<p> + Locks provide an explicit bool conversion operator when the compiler provides + them. + </p> +<pre class="programlisting"><span class="keyword">explicit</span> <span class="keyword">operator</span> <span class="keyword">bool</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> +</pre> +<p> + The library provides un implicit conversion to an undefined type that can + be used as a conditional expression. + </p> +<pre class="programlisting"><span class="preprocessor">#if</span> <span class="identifier">defined</span><span class="special">(</span><span class="identifier">BOOST_NO_EXPLICIT_CONVERSION_OPERATORS</span><span class="special">)</span> + <span class="keyword">operator</span> <span class="emphasis"><em>unspecified-bool-type</em></span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> + <span class="keyword">bool</span> <span class="keyword">operator</span><span class="special">!()</span> <span class="keyword">const</span><span class="special">;</span> +<span class="preprocessor">#else</span> + <span class="keyword">explicit</span> <span class="keyword">operator</span> <span class="keyword">bool</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> +<span class="preprocessor">#endif</span> +</pre> +<p> + The user should use the lock.owns_lock() when a explicit conversion is required. + </p> +<div class="section"> +<div class="titlepage"><div><div><h4 class="title"> +<a name="thread.emulations.bool_explicit_conversion.bool_conversion"></a><a class="link" href="emulations.html#thread.emulations.bool_explicit_conversion.bool_conversion" title="operator unspecified-bool-type() const"><code class="computeroutput"><span class="keyword">operator</span> </code><span class="emphasis"><em>unspecified-bool-type</em></span><code class="computeroutput"><span class="special">()</span> <span class="keyword">const</span></code></a> +</h4></div></div></div> +<div class="variablelist"> +<p class="title"><b></b></p> +<dl> +<dt><span class="term">Returns:</span></dt> +<dd><p> + If <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a> + would return <code class="computeroutput"><span class="keyword">true</span></code>, a + value that evaluates to <code class="computeroutput"><span class="keyword">true</span></code> + in boolean contexts, otherwise a value that evaluates to <code class="computeroutput"><span class="keyword">false</span></code> in boolean contexts. + </p></dd> +<dt><span class="term">Throws:</span></dt> +<dd><p> + Nothing. + </p></dd> +</dl> +</div> +</div> +<div class="section"> +<div class="titlepage"><div><div><h4 class="title"> +<a name="thread.emulations.bool_explicit_conversion.operator_not"></a><a class="link" href="emulations.html#thread.emulations.bool_explicit_conversion.operator_not" title="bool operator!() const"><code class="computeroutput"><span class="keyword">bool</span> <span class="keyword">operator</span><span class="special">!()</span> <span class="keyword">const</span></code></a> +</h4></div></div></div> +<div class="variablelist"> +<p class="title"><b></b></p> +<dl> +<dt><span class="term">Returns:</span></dt> +<dd><p> + <code class="computeroutput"><span class="special">!</span></code> <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>. + </p></dd> +<dt><span class="term">Throws:</span></dt> +<dd><p> + Nothing. + </p></dd> +</dl> +</div> +</div> +</div> +<div class="section"> +<div class="titlepage"><div><div><h3 class="title"> +<a name="thread.emulations.scoped_enums"></a><a class="link" href="emulations.html#thread.emulations.scoped_enums" title="Scoped Enums">Scoped Enums</a> +</h3></div></div></div> +<p> + Some of the enumerations defined in the standard library are scoped enums. + </p> +<p> + On compilers that don't support them, the library uses a class to wrap the + underlying type. Instead of + </p> +<pre class="programlisting"><span class="keyword">enum</span> <span class="keyword">class</span> <span class="identifier">future_errc</span> +<span class="special">{</span> + <span class="identifier">broken_promise</span><span class="special">,</span> + <span class="identifier">future_already_retrieved</span><span class="special">,</span> + <span class="identifier">promise_already_satisfied</span><span class="special">,</span> + <span class="identifier">no_state</span> +<span class="special">};</span> +</pre> +<p> + the library declare these types as + </p> +<pre class="programlisting"><span class="identifier">BOOST_SCOPED_ENUM_DECLARE_BEGIN</span><span class="special">(</span><span class="identifier">future_errc</span><span class="special">)</span> +<span class="special">{</span> + <span class="identifier">broken_promise</span><span class="special">,</span> + <span class="identifier">future_already_retrieved</span><span class="special">,</span> + <span class="identifier">promise_already_satisfied</span><span class="special">,</span> + <span class="identifier">no_state</span> +<span class="special">}</span> +<span class="identifier">BOOST_SCOPED_ENUM_DECLARE_END</span><span class="special">(</span><span class="identifier">future_errc</span><span class="special">)</span> +</pre> +<p> + These macros allows to use 'future_errc' in almost all the cases as an scoped + enum. + </p> +<p> + There are however some limitations: + </p> +<div class="itemizedlist"><ul class="itemizedlist" type="disc"> +<li class="listitem"> + The type is not a C++ enum, so 'is_enum<future_errc>' will be false_type. + </li> +<li class="listitem"> + The emulated scoped enum can not be used in switch nor in template arguments. + For these cases the user needs to use some macros. + </li> +</ul></div> +<p> + Instead of + </p> +<pre class="programlisting"> <span class="keyword">switch</span> <span class="special">(</span><span class="identifier">ev</span><span class="special">)</span> + <span class="special">{</span> + <span class="keyword">case</span> <span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">broken_promise</span><span class="special">:</span> +<span class="comment">// ...</span> +</pre> +<p> + use + </p> +<pre class="programlisting"><span class="keyword">switch</span> <span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">native_value</span><span class="special">(</span><span class="identifier">ev</span><span class="special">))</span> +<span class="special">{</span> +<span class="keyword">case</span> <span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">broken_promise</span><span class="special">:</span> +</pre> +<p> + And instead of + </p> +<pre class="programlisting"><span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_NO_SCOPED_ENUMS</span> +<span class="keyword">template</span> <span class="special"><></span> +<span class="keyword">struct</span> <span class="identifier">BOOST_SYMBOL_VISIBLE</span> <span class="identifier">is_error_code_enum</span><span class="special"><</span><span class="identifier">future_errc</span><span class="special">></span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">true_type</span> <span class="special">{</span> <span class="special">};</span> +<span class="preprocessor">#endif</span> +</pre> +<p> + use + </p> +<pre class="programlisting"><span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_NO_SCOPED_ENUMS</span> +<span class="keyword">template</span> <span class="special"><></span> +<span class="keyword">struct</span> <span class="identifier">BOOST_SYMBOL_VISIBLE</span> <span class="identifier">is_error_code_enum</span><span class="special"><</span><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">enum_type</span><span class="special">></span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">true_type</span> <span class="special">{</span> <span class="special">};</span> +<span class="preprocessor">#endif</span> +</pre> +</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 © 2007 -11 Anthony Williams<br>Copyright © 2011 -12 Vicente J. Botet Escriba<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> +</div></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="time.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../thread.html"><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="acknowledgements.html"><img src="../../../doc/src/images/next.png" alt="Next"></a> +</div> +</body> +</html> |