| .. Macros/Broken Compiler Workarounds//BOOST_MPL_AUX_LAMBDA_SUPPORT |
| |
| BOOST_MPL_AUX_LAMBDA_SUPPORT |
| ============================ |
| |
| Synopsis |
| -------- |
| |
| .. parsed-literal:: |
| |
| #define BOOST_MPL_AUX_LAMBDA_SUPPORT(arity, fun, params) \\ |
| |unspecified-token-seq| \\ |
| /\*\*/ |
| |
| |
| |
| Description |
| ----------- |
| |
| Enables metafunction ``fun`` for the use in |Lambda Expression|\ s on |
| compilers that don't support partial template specialization or/and |
| template template parameters. Expands to nothing on conforming compilers. |
| |
| |
| Header |
| ------ |
| |
| .. parsed-literal:: |
| |
| #include <boost/mpl/aux\_/lambda_support.hpp> |
| |
| |
| Parameters |
| ---------- |
| |
| +---------------+-------------------------------+---------------------------------------------------+ |
| | Parameter | Requirement | Description | |
| +===============+===============================+===================================================+ |
| | ``arity`` | An integral constant | The metafunction's arity, i.e. the number of its | |
| | | | template parameters, including the defaults. | |
| +---------------+-------------------------------+---------------------------------------------------+ |
| | ``fun`` | A legal identifier token | The metafunction's name. | |
| +---------------+-------------------------------+---------------------------------------------------+ |
| | ``params`` | A |PP-tuple| | A tuple of the metafunction's parameter names, in | |
| | | | their original order, including the defaults. | |
| +---------------+-------------------------------+---------------------------------------------------+ |
| |
| |
| Expression semantics |
| -------------------- |
| |
| For any integral constant ``n``, a |Metafunction| ``fun``, and arbitrary types |A1...An|: |
| |
| |
| .. parsed-literal:: |
| |
| template< typename A1,\ |...| typename A\ *n* > struct fun |
| { |
| // |...| |
| |
| BOOST_MPL_AUX_LAMBDA_SUPPORT(n, fun, (A1,\ |...|\ A\ *n*\ )) |
| }; |
| |
| :Precondition: |
| Appears in ``fun``\ 's scope, immediately followed by the scope-closing |
| bracket (``}``). |
| |
| :Return type: |
| None. |
| |
| :Semantics: |
| Expands to nothing and has no effect on conforming compilers. On compilers that |
| don't support partial template specialization or/and template template parameters |
| expands to an unspecified token sequence enabling ``fun`` to participate in |
| |Lambda Expression|\ s with the semantics described in this manual. |
| |
| |
| Example |
| ------- |
| |
| .. parsed-literal:: |
| |
| template< typename T, typename U = int > struct f |
| { |
| typedef T type[sizeof(U)]; |
| |
| BOOST_MPL_AUX_LAMBDA_SUPPORT(2, f, (T,U)) |
| }; |
| |
| typedef apply\ ``1``\< f<char,_1>,long >::type r; |
| BOOST_MPL_ASSERT(( is_same< r, char[sizeof(long)] > )); |
| |
| |
| See also |
| -------- |
| |
| |Macros|, |Metafunctions|, |Lambda Expression| |
| |
| |
| .. |PP-tuple| replace:: `PP-tuple <http://www.boost.org/libs/preprocessor/doc/data/tuples.html>`__ |
| |
| |
| .. copyright:: Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |