Variable templates for type traits (library fundamentals TS)

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Library fundamentals

Version 1 of the C++ Extensions for Library Fundamentals provides a number of constexpr variable templates for type traits classes, as well as other similar class templates with public ::value

Unless otherwise noted, the following variable templates are defined in the std::experimental namespace.

Type traits

Primary type categories
Variable template Value
Defined in header <experimental/type_traits>
template < class T> constexpr bool is_void_v = std::is_void <T> :: value ;
template < class T> constexpr bool is_null_pointer_v = std::is_null_pointer <T> :: value ;
template < class T> constexpr bool is_integral_v = std::is_integral <T> :: value ;
template < class T> constexpr bool is_floating_point_v = std::is_floating_point <T> :: value ;
template < class T> constexpr bool is_array_v = std::is_array <T> :: value ;
template < class T> constexpr bool is_pointer_v = std::is_pointer <T> :: value ;
template < class T> constexpr bool is_lvalue_reference_v = std::is_lvalue_reference <T> :: value ;
template < class T> constexpr bool is_rvalue_reference_v = std::is_rvalue_reference <T> :: value ;
template < class T> constexpr bool is_member_object_pointer_v = std::is_member_object_pointer <T> :: value ;
template < class T> constexpr bool is_member_function_pointer_v = std::is_member_function_pointer <T> :: value ;
template < class T> constexpr bool is_enum_v = std::is_enum <T> :: value ;
template < class T> constexpr bool is_union_v = std::is_union <T> :: value ;
template < class T> constexpr bool is_class_v = std::is_class <T> :: value ;
template < class T> constexpr bool is_function_v = std::is_function <T> :: value ;
Composite type categories
Variable template Value
Defined in header <experimental/type_traits>
template < class T> constexpr bool is_reference_v = std::is_reference <T> :: value ;
template < class T> constexpr bool is_arithmetic_v = std::is_arithmetic <T> :: value ;
template < class T> constexpr bool is_fundamental_v = std::is_fundamental <T> :: value ;
template < class T> constexpr bool is_object_v = std::is_object <T> :: value ;
template < class T> constexpr bool is_scalar_v = std::is_scalar <T> :: value ;
template < class T> constexpr bool is_compound_v = std::is_compound <T> :: value ;
template < class T> constexpr bool is_member_pointer_v = std::is_member_pointer <T> :: value ;
Type properties
Variable template Value
Defined in header <experimental/type_traits>
template < class T> constexpr bool is_const_v = std::is_const <T> :: value ;
template < class T> constexpr bool is_volatile_v = std::is_volatile <T> :: value ;
template < class T> constexpr bool is_trivial_v = std::is_trivial <T> :: value ;
template < class T> constexpr bool is_trivially_copyable_v = std::is_trivially_copyable <T> :: value ;
template < class T> constexpr bool is_standard_layout_v = std::is_standard_layout <T> :: value ;
template < class T> constexpr bool is_pod_v = std::is_pod <T> :: value ;
template < class T> constexpr bool is_literal_type_v = std::is_literal_type <T> :: value ;
template < class T> constexpr bool is_empty_v = std::is_empty <T> :: value ;
template < class T> constexpr bool is_polymorphic_v = std::is_polymorphic <T> :: value ;
template < class T> constexpr bool is_abstract_v = std::is_abstract <T> :: value ;
template < class T> constexpr bool is_final_v = std::is_final <T> :: value ;
template < class T> constexpr bool is_signed_v = std::is_signed <T> :: value ;
template < class T> constexpr bool is_unsigned_v = std::is_unsigned <T> :: value ;
Supported operations
Variable template Value
Defined in header <experimental/type_traits>
template < class T, class... Args > constexpr bool is_constructible_v = std::is_constructible <T, Args...> :: value ;
template < class T, class... Args > constexpr bool is_trivially_constructible_v = std::is_trivially_constructible <T, Args...> :: value ;
template < class T, class... Args > constexpr bool is_nothrow_constructible_v = std::is_nothrow_constructible <T, Args...> :: value ;
template < class T> constexpr bool is_default_constructible_v = std::is_default_constructible <T> :: value ;
template < class T> constexpr bool is_trivially_default_constructible_v = std::is_trivially_default_constructible <T> :: value ;
template < class T> constexpr bool is_nothrow_default_constructible_v = std::is_nothrow_default_constructible <T> :: value ;
template < class T> constexpr bool is_copy_constructible_v = std::is_copy_constructible <T> :: value ;
template < class T> constexpr bool is_trivially_copy_constructible_v = std::is_trivially_copy_constructible <T> :: value ;
template < class T> constexpr bool is_nothrow_copy_constructible_v = std::is_nothrow_copy_constructible <T> :: value ;
template < class T> constexpr bool is_move_constructible_v = std::is_move_constructible <T> :: value ;
template < class T> constexpr bool is_trivially_move_constructible_v = std::is_trivially_move_constructible <T> :: value ;
template < class T> constexpr bool is_nothrow_move_constructible_v = std::is_nothrow_move_constructible <T> :: value ;
template < class T, class U> constexpr bool is_assignable_v = std::is_assignable <T, U> :: value ;
template < class T, class U> constexpr bool is_trivially_assignable_v = std::is_trivially_assignable <T, U> :: value ;
template < class T, class U> constexpr bool is_nothrow_assignable_v = std::is_nothrow_assignable <T, U> :: value ;
template < class T> constexpr bool is_copy_assignable_v = std::is_copy_assignable <T> :: value ;
template < class T> constexpr bool is_trivially_copy_assignable_v = std::is_trivially_copy_assignable <T> :: value ;
template < class T> constexpr bool is_nothrow_copy_assignable_v = std::is_nothrow_copy_assignable <T> :: value ;
template < class T> constexpr bool is_move_assignable_v = std::is_move_assignable <T> :: value ;
template < class T> constexpr bool is_trivially_move_assignable_v = std::is_trivially_move_assignable <T> :: value ;
template < class T> constexpr bool is_nothrow_move_assignable_v = std::is_nothrow_move_assignable <T> :: value ;
template < class T> constexpr bool is_destructible_v = std::is_destructible <T> :: value ;
template < class T> constexpr bool is_trivially_destructible_v = std::is_trivially_destructible <T> :: value ;
template < class T> constexpr bool is_nothrow_destructible_v = std::is_nothrow_destructible <T> :: value ;
template < class T> constexpr bool has_virtual_destructor_v = std::has_virtual_destructor <T> :: value ;
Property queries
Variable template Value
Defined in header <experimental/type_traits>
template < class T> constexpr std::size_t alignment_of_v = std::alignment_of <T> :: value ;
template < class T> constexpr std::size_t rank_v = std::rank <T> :: value ;
template < class T, unsigned I = 0 > constexpr std::size_t extent_v = std::extent <T, I> :: value ;
Type relationships
Variable template Value
Defined in header <experimental/type_traits>
template < class T, class U> constexpr bool is_same_v = std::is_same <T, U> :: value ;
template < class Base, class Derived> constexpr bool is_base_of_v = std::is_base_of <Base, Derived> :: value ;
template < class From, class To> constexpr bool is_convertible_v = std::is_convertible <From, To> :: value ;

Other variable templates

std::ratio comparison
Variable template Value
Defined in header <experimental/ratio>
template < class R1, class R2> constexpr bool ratio_equal_v = std::ratio_equal <R1, R2> :: value ;
template < class R1, class R2> constexpr bool ratio_not_equal_v = std::ratio_not_equal <R1, R2> :: value ;
template < class R1, class R2> constexpr bool ratio_less_v = std::ratio_less <R1, R2> :: value ;
template < class R1, class R2> constexpr bool ratio_less_equal_v = std::ratio_less_equal <R1, R2> :: value ;
template < class R1, class R2> constexpr bool ratio_greater_v = std::ratio_greater <R1, R2> :: value ;
template < class R1, class R2> constexpr bool ratio_greater_equal_v = std::ratio_greater_equal <R1, R2> :: value ;
Miscellaneous
Variable template Value
Defined in header <experimental/tuple>
template < class T> constexpr std::size_t tuple_size_v = std::tuple_size <T> :: value ;
Defined in header <experimental/chrono>
template < class Rep> constexpr bool treat_as_floating_point_v = std::chrono::treat_as_floating_point <Rep> :: value ; [1]
Defined in header <experimental/system_error>
template < class T> constexpr bool is_error_code_enum_v = std::is_error_code_enum <T> :: value ;
template < class T> constexpr bool is_error_condition_enum_v = std::is_error_condition_enum <T> :: value ;
Defined in header <experimental/functional>
template < class T> constexpr bool is_bind_expression_v = std::is_bind_expression <T> :: value ;
template < class T> constexpr int is_placeholder_v = std::is_placeholder <T> :: value ;
Defined in header <experimental/memory>
template < class T, class Alloc> constexpr bool uses_allocator_v = std::uses_allocator <T, Alloc> :: value ;

Notes

[1]: Defined in the std::chrono::experimental namespace.

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