C++ named requirements: UnaryTypeTrait

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UnaryTypeTrait
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
 

A UnaryTypeTrait is a class template that describes a property of its template type parameter with a intergral_constant (typically 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 intergral_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 properties all satisfy UnaryTypeTrait.

  • Primary type categories
  • Composite type categories
  • Type properties
  • Supported operations
  • Property queries


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)
obtains the size of tuple at compile time
(class template specialization)
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)