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

 

C++

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C++ named requirements

Basic
DefaultConstructible CopyAssignable	CopyConstructible MoveAssignable (C++11)	MoveConstructible (C++11) Destructible
Type properties
ScalarType TriviallyCopyable (C++11)	StandardLayoutType (C++11) PODType	TrivialType (C++11) ImplicitLifetimeType
Library-Wide
EqualityComparable LessThanComparable Swappable ValueSwappable (C++11)	NullablePointer (C++11) Hash (C++11) Allocator FunctionObject	Callable Predicate BinaryPredicate Compare
Container
Container SequenceContainer ContiguousContainer (C++17)	ReversibleContainer AssociativeContainer AllocatorAwareContainer	UnorderedAssociativeContainer (C++11)
Container Elements
DefaultInsertable (C++11) CopyInsertable (C++11)	MoveInsertable (C++11) EmplaceConstructible (C++11)	Erasable (C++11)
Iterator
LegacyIterator LegacyOutputIterator LegacyInputIterator	LegacyForwardIterator LegacyBidirectionalIterator LegacyRandomAccessIterator	LegacyContiguousIterator (C++17) ConstexprIterator (C++20)
Stream I/O
FormattedInputFunction UnformattedInputFunction	FormattedOutputFunction	UnformattedOutputFunction
Formatters
BasicFormatter (C++20)	Formatter (C++20)
Random Numbers
SeedSequence (C++11) RandomNumberEngine (C++11)	RandomNumberDistribution (C++11) UniformRandomBitGenerator (C++11)	RandomNumberEngineAdaptor (C++11)
Concurrency
BasicLockable (C++11) Lockable (C++11) TimedLockable (C++11)	SharedLockable (C++14) SharedTimedLockable (C++14) Mutex (C++11)	TimedMutex (C++11) SharedMutex (C++17) SharedTimedMutex (C++14)
Ranges
RangeAdaptorObject (C++20)	RangeAdaptorClosureObject (C++20)
Other
CharTraits RegexTraits (C++11) BitmaskType LiteralType (C++11)	NumericType UnaryTypeTrait (C++11) BinaryTypeTrait (C++11) TransformationTrait (C++11)	Clock (C++11) TrivialClock (C++11)

 

The TrivialClock requirements describe the requirements satisfied by several clocks in the chrono library.

Requirements

For a type TC:

• The type must meet Clock requirements.
• The types TC::rep, TC::duration, and TC::time_point satisfy the requirements of EqualityComparable, LessThanComparable, DefaultConstructible, CopyConstructible, CopyAssignable, Destructible, and NumericType.
• lvalues of the types TC::rep, TC::duration, and TC::time_point are Swappable.
• The function TC::now() does not throw exceptions.
• The type TC::time_point::clock meets the TrivialClock requirements, recursively.

Usage

The following types in the standard library satisfy these requirements:

• std::chrono::system_clock
• std::chrono::steady_clock
• std::chrono::high_resolution_clock
• std::filesystem::file_time_type::clock
• std::chrono::file_clock