<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> <title>Actors</title> <link rel="stylesheet" href="../../../../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.75.2"> <link rel="home" href="../index.html" title="Chapter 1. Phoenix 2.0"> <link rel="up" href="../index.html" title="Chapter 1. Phoenix 2.0"> <link rel="prev" href="organization.html" title="Organization"> <link rel="next" href="primitives.html" title="Primitives"> </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="organization.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.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="primitives.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="phoenix.actors"></a><a class="link" href="actors.html" title="Actors">Actors</a> </h2></div></div></div> <p> The <code class="computeroutput"><span class="identifier">Actor</span></code> is the main concept behind the library. Actors are function objects. An actor can accept 0 to <code class="computeroutput"><span class="identifier">PHOENIX_LIMIT</span></code> arguments. </p> <div class="note"><table border="0" summary="Note"> <tr> <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../doc/src/images/note.png"></td> <th align="left">Note</th> </tr> <tr><td align="left" valign="top"><p> You can set <code class="computeroutput"><span class="identifier">PHOENIX_LIMIT</span></code>, the predefined maximum arity an actor can take. By default, <code class="computeroutput"><span class="identifier">PHOENIX_LIMIT</span></code> is set to 10. </p></td></tr> </table></div> <p> Phoenix supplies an <code class="computeroutput"><span class="identifier">actor</span></code> class template whose specializations model the <code class="computeroutput"><span class="identifier">Actor</span></code> concept. <code class="computeroutput"><span class="identifier">actor</span></code> has one template parameter, <code class="computeroutput"><span class="identifier">Eval</span></code>, that supplies the smarts to evaluate the resulting function. </p> <pre class="programlisting"><span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Eval</span><span class="special">></span> <span class="keyword">struct</span> <span class="identifier">actor</span> <span class="special">:</span> <span class="identifier">Eval</span> <span class="special">{</span> <span class="identifier">return_type</span> <span class="keyword">operator</span><span class="special">()()</span> <span class="keyword">const</span><span class="special">;</span> <span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">T0</span><span class="special">></span> <span class="identifier">return_type</span> <span class="keyword">operator</span><span class="special">()(</span><span class="identifier">T0</span><span class="special">&</span> <span class="identifier">_0</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="keyword">template</span> <span class="special"><</span><span class="keyword">typename</span> <span class="identifier">T0</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">T1</span><span class="special">></span> <span class="identifier">return_type</span> <span class="keyword">operator</span><span class="special">()(</span><span class="identifier">T0</span><span class="special">&</span> <span class="identifier">_0</span><span class="special">,</span> <span class="identifier">T1</span><span class="special">&</span> <span class="identifier">_1</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="comment">//... </span><span class="special">};</span> </pre> <p> The actor class accepts the arguments through a set of function call operators for 0 to <code class="computeroutput"><span class="identifier">PHOENIX_LIMIT</span></code> arities (Don't worry about the details, for now. Note, for example, that we skimp over the details regarding <code class="computeroutput"><span class="identifier">return_type</span></code>). The arguments are then forwarded to the actor's <code class="computeroutput"><span class="identifier">Eval</span></code> for evaluation. </p> </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 © 2002-2005 Joel de Guzman, Dan Marsden<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="organization.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../index.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="primitives.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>