Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
| Front Page / Metafunctions / Invocation / apply |
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 applyn
{
typedef unspecified type;
};
template<
typename F
, typename A1 = unspecified
...
, typename An = unspecified
>
struct apply
{
typedef unspecified type;
};
Invokes a Metafunction Class or a Lambda Expression F with arguments A1,... An.
#include <boost/mpl/apply.hpp>
| Parameter | Requirement | Description |
|---|---|---|
| F | Lambda Expression | An expression to invoke. |
| A1,... An | Any type | Invocation arguments. |
For any Lambda Expression f and arbitrary types a1,... an:
typedef applyn<f,a1,...an>::type t; typedef apply<f,a1,...an>::type t;
| Return type: | Any type. |
|---|---|
| Semantics: | Equivalent to typedef apply_wrapn< lambda<f>::type,a1,... an>::type t;. |
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< quote2<int_plus>, int_<2>, int_<3> >::type r2;
BOOST_MPL_ASSERT_RELATION( r1::value, ==, 5 );
BOOST_MPL_ASSERT_RELATION( r2::value, ==, 5 );