3rdParty/boost/1.78.0/libs/mpl/doc/refmanual/apply-wrap.html
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template<
typename F
>
struct apply_wrap0
{
typedef_unspecified_type;
};
template<
typename F, typename A1
>
struct apply_wrap1
{
typedef_unspecified_type;
};_..._template<
typename F, typename A1,_..._typename An
>
struct[apply\_wrap](./apply-wrap.html)_n_{
typedef_unspecified_type;
};
Invokes a Metafunction Class F with arguments A1,... An.
In essence, apply_wrap forms are nothing more than syntactic wrappers around F::apply<A1,... An>::type / F::apply::type expressions (hence the name). They provide a more concise notation and higher portability than their underlaying constructs at the cost of an extra template instantiation.
#include <[boost/mpl/apply\_wrap.hpp](../../../../boost/mpl/apply_wrap.hpp)>
| Parameter | Requirement | Description |
|---|---|---|
| F | Metafunction Class | A metafunction class to invoke. |
| A1,... An | Any type | Invocation arguments. |
For any Metafunction Class f and arbitrary types a1,... an:
typedef[apply\_wrap](./apply-wrap.html)_n_<f,a1,_..._an>::type t;
| Return type: | Any type. | | Semantics: | If n > 0, equivalent to typedef f::apply<a1,... an>::type t;, otherwise equivalent to either typedef f::apply::type t; or typedef f::apply<>::type t; depending on whether f::apply is a class or a class template. |
struct f0
{
template< typename T = int > struct[apply](./apply.html){
typedef char type;
};
};
struct g0
{
struct[apply](./apply.html){ typedef char type; };
};
struct f2
{
template< typename T1, typename T2 > struct[apply](./apply.html){
typedef T2 type;
};
};
typedef[apply\_wrap](./apply-wrap.html)0< f0 >::type r1;
typedef[apply\_wrap](./apply-wrap.html)0< g0 >::type r2;
typedef[apply\_wrap](./apply-wrap.html)2< f2,int,char >::type r3;[BOOST\_MPL\_ASSERT](./assert.html)(( is_same<r1,char> ));[BOOST\_MPL\_ASSERT](./assert.html)(( is_same<r2,char> ));[BOOST\_MPL\_ASSERT](./assert.html)(( is_same<r3,char> ));
Metafunctions, invocation, apply, lambda, quote, bind, protect
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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) |