hpx::is_placeholder

Defined in header hpx/functional.hpp.

See Public API for a list of names and headers that are part of the public HPX API.

namespace hpx

Top level namespace.

template<typename T>
struct is_placeholder

#include <is_placeholder.hpp>

If T is a standard, Boost, or HPX placeholder (_1, _2, _3, …) then this template is derived from std::integral_constant<int,1>, std::integral_constant<int,2>, std::integral_constant<int,3>, respectively. Otherwise, it is derived from std::integral_constant<int,0>.

The template may be specialized for any user-defined T type: the specialization must satisfy UnaryTypeTrait with base characteristic of std::integral_constant<int,N> with N>0 to indicate that T should be treated as N’th placeholder type. hpx::bind uses hpx::is_placeholder to detect placeholders for unbound arguments.