std::chrono::is_clock
Defined in header <chrono> |
||
---|---|---|
template< class T > struct is_clock; |
(since C++20) |
If T
satisfies the Clock requirements, provides the member constant value
equal true
. For any other type, value
is false
.
For the purpose of this trait, the extent to which an implementation determines that a type cannot meet the Clock requirements is unspecified, except that a minimum T
shall not qualify as a Clock unless it meets all of the following conditions:
- The qualified-ids
T::rep
,T::period
,T::duration
, andT::time_point
are all valid and each denotes a type; - The expressions
T::is_steady
andT::now()
are each well-formed when treated as an unevaluated operand.
The behavior of a program that adds specializations for is_clock
or is_clock_v
is undefined.
Template parameters
T | - | a type to check |
Helper variable template
template< class T > inline constexpr bool is_clock_v = is_clock<T>::value; |
(since C++20) |
Inherited from std::integral_constant
Member constants
value
[static]
|
true if T satisfies the Clock requirements , false otherwise (public static member constant) |
Member functions
operator bool
|
converts the object to bool , returns value (public member function) |
operator()
(C++14)
|
returns value (public member function) |
Member types
Type | Definition |
---|---|
value_type |
bool |
type |
std::integral_constant<bool, value> |
Possible implementation
template<class> struct is_clock : std::false_type {}; template<class T> requires requires { typename T::rep; typename T::period; typename T::duration; typename T::time_point; T::is_steady; T::now(); } struct is_clock<T> : std::true_type {}; |
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