| .. Metafunctions/Invocation//apply |10 |
| |
| apply |
| ===== |
| |
| Synopsis |
| -------- |
| |
| .. parsed-literal:: |
| |
| template< |
| typename F |
| > |
| struct apply0 |
| { |
| typedef |unspecified| type; |
| }; |
| |
| template< |
| typename F, typename A1 |
| > |
| struct apply1 |
| { |
| typedef |unspecified| type; |
| }; |
| |
| |...| |
| |
| template< |
| typename F, typename A1,\ |...| typename An |
| > |
| struct apply\ *n* |
| { |
| typedef |unspecified| type; |
| }; |
| |
| template< |
| typename F |
| , typename A1 = |unspecified| |
| |...| |
| , typename An = |unspecified| |
| > |
| struct apply |
| { |
| typedef |unspecified| type; |
| }; |
| |
| |
| |
| Description |
| ----------- |
| |
| Invokes a |Metafunction Class| or a |Lambda Expression| ``F`` with arguments ``A1``,... ``An``. |
| |
| |
| Header |
| ------ |
| |
| .. parsed-literal:: |
| |
| #include <boost/mpl/apply.hpp> |
| |
| |
| Parameters |
| ---------- |
| |
| +---------------+-----------------------------------+-----------------------------------------------+ |
| | Parameter | Requirement | Description | |
| +===============+===================================+===============================================+ |
| | ``F`` | |Lambda Expression| | An expression to invoke. | |
| +---------------+-----------------------------------+-----------------------------------------------+ |
| | |A1...An| | Any type | Invocation arguments. | |
| +---------------+-----------------------------------+-----------------------------------------------+ |
| |
| |
| Expression semantics |
| -------------------- |
| |
| For any |Lambda Expression| ``f`` and arbitrary types ``a1``,... ``an``: |
| |
| |
| .. parsed-literal:: |
| |
| typedef apply\ *n*\<f,a1,\ |...|\ a\ *n*\>::type t; |
| typedef apply<f,a1,\ |...|\ a\ *n*\>::type t; |
| |
| :Return type: |
| Any type. |
| |
| :Semantics: |
| Equivalent to ``typedef apply_wrap``\ *n*\ ``< lambda<f>::type,a1,... an>::type t;``. |
| |
| |
| Example |
| ------- |
| |
| .. parsed-literal:: |
| |
| template< typename N1, typename N2 > struct int_plus |
| : int_<( N1::value + N2::value )> |
| { |
| }; |
| |
| typedef apply< int_plus<_1,_2>, int_<2>, int_<3> >::type r1; |
| typedef apply< quote\ ``2``\ <int_plus>, int_<2>, int_<3> >::type r2; |
| |
| BOOST_MPL_ASSERT_RELATION( r1::value, ==, 5 ); |
| BOOST_MPL_ASSERT_RELATION( r2::value, ==, 5 ); |
| |
| |
| See also |
| -------- |
| |
| |Metafunctions|, |apply_wrap|, |lambda|, |quote|, |bind| |
| |
| |
| .. 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) |
