1[/==============================================================================
2    Copyright (C) 2001-2010 Joel de Guzman
3    Copyright (C) 2001-2005 Dan Marsden
4    Copyright (C) 2001-2010 Thomas Heller
5
6    Distributed under the Boost Software License, Version 1.0. (See accompanying
7    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
8===============================================================================/]
9
10[section Actor]
11
12The `Actor` is the main concept behind the library. Actors are function objects.
13An actor can accept 0 to `BOOST_PHOENIX_LIMIT` arguments.
14
15[note You can set `BOOST_PHOENIX_LIMIT`, the predefined maximum arity an
16actor can take. By default, `BOOST_PHOENIX_LIMIT` is set to 10.]
17
18Phoenix supplies an `actor` class template whose specializations
19model the `Actor` concept.  `actor` has one template parameter, `Expr`,
20that supplies the underlying expression to evaluate.
21
22    template <typename Expr>
23    struct actor
24    {
25        return_type
26        operator()() const;
27
28        template <typename T0>
29        return_type
30        operator()(T0& _0) const;
31
32        template <typename T0, typename T1>
33        return_type
34        operator()(T0& _0, T1& _1) const;
35
36        //...
37    };
38
39The actor class accepts the arguments through a set of function call operators
40for 0 to `BOOST_PHOENIX_LIMIT` arities (Don't worry about the details, for now. Note, for example,
41that we skimp over the details regarding `return_type`). The arguments are passed through to
42the evaluation mechanism. For more information see [link phoenix.inside.actor Inside Actors].
43
44[endsect]
45
46