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

 

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C++ named requirements

Basic DefaultConstructible MoveConstructible (C++11) CopyConstructible CopyAssignable MoveAssignable (C++11) Destructible Type properties ScalarType PODType TriviallyCopyable (C++11) TrivialType (C++11) StandardLayoutType (C++11)   ImplicitLifetimeType Library-wide BooleanTestable EqualityComparable LessThanComparable Swappable ValueSwappable (C++11) NullablePointer (C++11) Hash (C++11) Allocator FunctionObject Callable Predicate BinaryPredicate Compare

Container Container ReversibleContainer AllocatorAwareContainer SequenceContainer ContiguousContainer (C++17) AssociativeContainer UnorderedAssociativeContainer (C++11)   Container element DefaultInsertable (C++11) CopyInsertable (C++11) MoveInsertable (C++11) EmplaceConstructible (C++11) Erasable (C++11) Iterator LegacyIterator LegacyInputIterator LegacyOutputIterator 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) Multidimensional View LayoutMapping (C++23) LayoutMappingPolicy (C++23) AccessorPolicy (C++23) 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 Clock requirements describe a bundle consisting of a std::chrono::duration, a std::chrono::time_point, and a function now() to get the current time_point. The origin of the clock's time_point is referred to as the clock's epoch.

Requirements

C1 and C2 denote clock types. t1 and t2 are values returned by C1::now() where the call returning t1 happens before the call returning t2 and both of these calls occur before C1::time_point::max().

Expression	Return type	Operational semantics
C1::rep	An arithmetic type or a class emulating an arithmetic type	The representation type of C1::duration.
C1::period	A specialization of std::ratio	The tick period of the clock in seconds.
C1::duration	std::chrono::duration<C1::rep, C1::period>	The duration type of the clock.
C1::time_point	std::chrono::time_point<C1> or std::chrono::time_point<C2, C1::duration>	The std::chrono::time_point type of the clock. C1 and C2 shall refer to the same epoch.
C1::is_steady	const bool	true if t1 <= t2 is always true and the clock advances at a steady rate relative to real time (so the difference between two distinct reported times is approximately the elapsed real time between the clock updates), otherwise false
C1::now()	C1::time_point	Returns a time_point object representing the current point in time.

See also

is_clockis_clock_v (C++20)

determines if a type is a Clock (class template) (variable template)