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

   1 .. Macros/Broken Compiler Workarounds//BOOST_MPL_AUX_LAMBDA_SUPPORT
   2
   3 BOOST_MPL_AUX_LAMBDA_SUPPORT
   4 ============================
   5
   6 Synopsis
   7 --------
   8
   9 .. parsed-literal::
  10
  11     #define BOOST_MPL_AUX_LAMBDA_SUPPORT(arity, fun, params) \\
  12         |unspecified-token-seq| \\
  13     /\*\*/
  14
  15
  16
  17 Description
  18 -----------
  19
  20 Enables metafunction ``fun`` for the use in |Lambda Expression|\ s on
  21 compilers that don't support partial template specialization or/and
  22 template template parameters. Expands to nothing on conforming compilers.
  23
  24
  25 Header
  26 ------
  27
  28 .. parsed-literal::
  29
  30     #include <boost/mpl/aux\_/lambda_support.hpp>
  31
  32
  33 Parameters
  34 ----------
  35
  36 +---------------+-------------------------------+---------------------------------------------------+
  37 | Parameter     | Requirement                   | Description                                       |
  38 +===============+===============================+===================================================+
  39 | ``arity``     | An integral constant          | The metafunction's arity, i.e. the number of its  |
  40 |               |                               | template parameters, including the defaults.      |
  41 +---------------+-------------------------------+---------------------------------------------------+
  42 | ``fun``       | A legal identifier token      | The metafunction's name.                          |
  43 +---------------+-------------------------------+---------------------------------------------------+
  44 | ``params``    | A |PP-tuple|                  | A tuple of the metafunction's parameter names, in |
  45 |               |                               | their original order, including the defaults.     |
  46 +---------------+-------------------------------+---------------------------------------------------+
  47
  48
  49 Expression semantics
  50 --------------------
  51
  52 For any integral constant ``n``, a |Metafunction| ``fun``, and arbitrary types |A1...An|:
  53
  54
  55 .. parsed-literal::
  56
  57     template< typename A1,\ |...| typename A\ *n* > struct fun
  58     {
  59         // |...|
  60
  61         BOOST_MPL_AUX_LAMBDA_SUPPORT(n, fun, (A1,\ |...|\ A\ *n*\ ))
  62     };
  63
  64 :Precondition:
  65     Appears in ``fun``\ 's scope, immediately followed by the scope-closing
  66     bracket (``}``).
  67
  68 :Return type:
  69     None.
  70
  71 :Semantics:
  72     Expands to nothing and has no effect on conforming compilers. On compilers that
  73     don't support partial template specialization or/and template template parameters
  74     expands to an unspecified token sequence enabling ``fun`` to participate in
  75     |Lambda Expression|\ s with the semantics described in this manual.
  76
  77
  78 Example
  79 -------
  80
  81 .. parsed-literal::
  82
  83     template< typename T, typename U = int > struct f
  84     {
  85         typedef T type[sizeof(U)];
  86
  87         BOOST_MPL_AUX_LAMBDA_SUPPORT(2, f, (T,U))
  88     };
  89
  90     typedef apply\ ``1``\< f<char,_1>,long >::type r;
  91     BOOST_MPL_ASSERT(( is_same< r, char[sizeof(long)] > ));
  92
  93
  94 See also
  95 --------
  96
  97 |Macros|, |Metafunctions|, |Lambda Expression|
  98
  99
 100 .. |PP-tuple| replace:: `PP-tuple <http://www.boost.org/libs/preprocessor/doc/data/tuples.html>`__
 101
 102
 103 .. copyright:: Copyright ©  2001-2009 Aleksey Gurtovoy and David Abrahams
 104    Distributed under the Boost Software License, Version 1.0. (See accompanying
 105    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)