C++ named requirements: UnaryTypeTrait (since C++11)

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C++ named requirements

A UnaryTypeTrait is a class template that describes a property of its template type parameter with an std::integral_constant (typically std::bool_constant ) specialization.

Requirements

  • DefaultConstructible and CopyConstructible .
  • Takes one template type parameter (additional template parameters are optional and allowed).
  • Publicly and unambiguously derived from a specialization of std::integral_constant , known as its base characteristic .
  • The member names of the base characteristic are not hidden and are unambiguously available.

Standard library

The following type traits all satisfy UnaryTypeTrait :

The following standard library class templates also satisfy UnaryTypeTrait .

(C++11)
compile-time constant of specified type with specified value
(class template)
(C++17)
logical NOT metafunction
(class template)
(C++11)
obtains the size of

a tuple
(class template specialization)

(C++11)
obtains the size of an array
(class template specialization)
(C++11)
obtains the size of a pair
(class template specialization)
(C++17)
obtains the size of the variant 's list of alternatives at compile time
(class template) (variable template)
(C++11)
indicates that an object is std::bind expression or can be used as one
(class template)
(C++11)
indicates that an object is a standard placeholder or can be used as one
(class template)
(C++17)
test whether a class represents an execution policy
(class template)
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