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26 <div class=
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"title" style=
"clear: both">
27 <a name=
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"link" href=
"actor.html" title=
"Actor">Actor
</a>
28 </h2></div></div></div>
30 The
<code class=
"computeroutput"><span class=
"identifier">Actor
</span></code> is the main concept
31 behind the library. Actors are function objects. An actor can accept
0 to
32 <code class=
"computeroutput"><span class=
"identifier">BOOST_PHOENIX_LIMIT
</span></code> arguments.
34 <div class=
"note"><table border=
"0" summary=
"Note">
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"[Note]" src=
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37 <th align=
"left">Note
</th>
39 <tr><td align=
"left" valign=
"top"><p>
40 You can set
<code class=
"computeroutput"><span class=
"identifier">BOOST_PHOENIX_LIMIT
</span></code>,
41 the predefined maximum arity an actor can take. By default,
<code class=
"computeroutput"><span class=
"identifier">BOOST_PHOENIX_LIMIT
</span></code> is set to
10.
45 Phoenix supplies an
<code class=
"computeroutput"><span class=
"identifier">actor
</span></code> class
46 template whose specializations model the
<code class=
"computeroutput"><span class=
"identifier">Actor
</span></code>
47 concept.
<code class=
"computeroutput"><span class=
"identifier">actor
</span></code> has one template
48 parameter,
<code class=
"computeroutput"><span class=
"identifier">Expr
</span></code>, that supplies
49 the underlying expression to evaluate.
51 <pre class=
"programlisting"><span class=
"keyword">template
</span> <span class=
"special"><</span><span class=
"keyword">typename
</span> <span class=
"identifier">Expr
</span><span class=
"special">></span>
52 <span class=
"keyword">struct
</span> <span class=
"identifier">actor
</span>
53 <span class=
"special">{
</span>
54 <span class=
"identifier">return_type
</span>
55 <span class=
"keyword">operator
</span><span class=
"special">()()
</span> <span class=
"keyword">const
</span><span class=
"special">;
</span>
57 <span class=
"keyword">template
</span> <span class=
"special"><</span><span class=
"keyword">typename
</span> <span class=
"identifier">T0
</span><span class=
"special">></span>
58 <span class=
"identifier">return_type
</span>
59 <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>
61 <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>
62 <span class=
"identifier">return_type
</span>
63 <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>
65 <span class=
"comment">//...
</span>
66 <span class=
"special">};
</span>
69 The actor class accepts the arguments through a set of function call operators
70 for
0 to
<code class=
"computeroutput"><span class=
"identifier">BOOST_PHOENIX_LIMIT
</span></code>
71 arities (Don't worry about the details, for now. Note, for example, that we
72 skimp over the details regarding
<code class=
"computeroutput"><span class=
"identifier">return_type
</span></code>).
73 The arguments are passed through to the evaluation mechanism. For more information
74 see
<a class=
"link" href=
"inside/actor.html" title=
"Actors in Detail">Inside Actors
</a>.
77 <table xmlns:
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78 <td align=
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79 <td align=
"right"><div class=
"copyright-footer">Copyright
© 2002-
2005,
2010,
2014,
2015 Joel de Guzman, Dan Marsden, Thomas
80 Heller, John Fletcher
<p>
81 Distributed under the Boost Software License, Version
1.0. (See accompanying
82 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>)
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