ceph/src/boost/libs/mpl/doc/src/refmanual/apply.rst

   1 .. Metafunctions/Invocation//apply |10
   2
   3 apply
   4 =====
   5
   6 Synopsis
   7 --------
   8
   9 .. parsed-literal::
  10
  11     template<
  12           typename F
  13         >
  14     struct apply0
  15     {
  16         typedef |unspecified| type;
  17     };
  18
  19     template<
  20           typename F, typename A1
  21         >
  22     struct apply1
  23     {
  24         typedef |unspecified| type;
  25     };
  26
  27     |...|
  28
  29     template<
  30           typename F, typename A1,\ |...| typename An
  31         >
  32     struct apply\ *n*
  33     {
  34         typedef |unspecified| type;
  35     };
  36
  37     template<
  38           typename F
  39         , typename A1 = |unspecified|
  40         |...|
  41         , typename An = |unspecified|
  42         >
  43     struct apply
  44     {
  45         typedef |unspecified| type;
  46     };
  47
  48
  49
  50 Description
  51 -----------
  52
  53 Invokes a |Metafunction Class| or a |Lambda Expression| ``F`` with arguments ``A1``,... ``An``.
  54
  55
  56 Header
  57 ------
  58
  59 .. parsed-literal::
  60
  61     #include <boost/mpl/apply.hpp>
  62
  63
  64 Parameters
  65 ----------
  66
  67 +---------------+-----------------------------------+-----------------------------------------------+
  68 | Parameter     | Requirement                       | Description                                   |
  69 +===============+===================================+===============================================+
  70 | ``F``         | |Lambda Expression|               | An expression to invoke.                      |
  71 +---------------+-----------------------------------+-----------------------------------------------+
  72 | |A1...An|     | Any type                          | Invocation arguments.                         |
  73 +---------------+-----------------------------------+-----------------------------------------------+
  74
  75
  76 Expression semantics
  77 --------------------
  78
  79 For any |Lambda Expression| ``f`` and arbitrary types ``a1``,... ``an``:
  80
  81
  82 .. parsed-literal::
  83
  84     typedef apply\ *n*\<f,a1,\ |...|\ a\ *n*\>::type t;
  85     typedef apply<f,a1,\ |...|\ a\ *n*\>::type t;
  86
  87 :Return type:
  88     Any type.
  89
  90 :Semantics:
  91     Equivalent to ``typedef apply_wrap``\ *n*\ ``< lambda<f>::type,a1,... an>::type t;``.
  92
  93
  94 Example
  95 -------
  96
  97 .. parsed-literal::
  98
  99     template< typename N1, typename N2 > struct int_plus
 100         : int_<( N1::value + N2::value )>
 101     {
 102     };
 103
 104     typedef apply< int_plus<_1,_2>, int_<2>, int_<3> >::type r1;
 105     typedef apply< quote\ ``2``\ <int_plus>, int_<2>, int_<3> >::type r2;
 106
 107     BOOST_MPL_ASSERT_RELATION( r1::value, ==, 5 );
 108     BOOST_MPL_ASSERT_RELATION( r2::value, ==, 5 );
 109
 110
 111 See also
 112 --------
 113
 114 |Metafunctions|, |apply_wrap|, |lambda|, |quote|, |bind|
 115
 116
 117 .. copyright:: Copyright ©  2001-2009 Aleksey Gurtovoy and David Abrahams
 118    Distributed under the Boost Software License, Version 1.0. (See accompanying
 119    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)