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Section: 29.3 [time.clock.req] Status: C++11 Submitter: Pete Becker Opened: 2009-01-07 Last modified: 2016-01-28
Priority: Not Prioritized
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Discussion:
29.3 [time.clock.req] uses the word "native" in several places,
but doesn't define it. What is a "native duration
"?
[ 2009-05-10 Howard adds: ]
The standard uses "native" in several places without defining it (e.g. 5.13.3 [lex.ccon]). It is meant to mean "that which is defined by the facility", or something along those lines. In this case it refers to the nested
time_point
andduration
types of the clock. Better wording is welcome.
[ Batavia (2009-05): ]
Move to Open pending proposed wording from Pete.
[ 2009-10-23 Pete provides wording: ]
[ 2009-11-18 Daniel adds: ]
I see that 33.6.4.3 [thread.timedmutex.requirements]/3 says:
Precondition: If the tick
period
ofrel_time
is not exactly convertible to the native tickperiod
, theduration
shall be rounded up to the nearest native tickperiod
.I would prefer to see that adapted as well. Following the same style as the proposed resolution I come up with
Precondition: If the tick
period
ofrel_time
is not exactly convertible to thenativetickperiod
of the execution environment, theduration
shall be rounded up to the nearestnativetickperiod
of the execution environment.
[ 2010-03-28 Daniel synced wording with N3092 ]
[ Post-Rapperswil, Howard provides wording: ]
Moved to Tentatively Ready with revised wording from Howard Hinnant after 5 positive votes on c++std-lib.
[ Adopted at 2010-11 Batavia ]
Proposed resolution:
Change 29.3 [time.clock.req]:
1 A clock is a bundle consisting of a
nativeduration
, anativetime_point
, and a functionnow()
to get the currenttime_point
. The origin of the clock'stime_point
is referred to as the clock's epoch. A clock shall meet the requirements in Table 56.2 ...
Table 56 — Clock requirements Expression Return type Operational semantics C1::rep
An arithmetic type or a class emulating an arithmetic type The representation type of the nativeC1::duration
.andtime_point
.C1::period
... ... C1::duration
chrono::duration<C1::rep, C1::period>
The nativeduration
type of the clock.C1::time_point
chrono::time_point<C1>
orchrono::time_point<C2, C1::duration>
The nativetime_point
type of the clock.C1
andC2
shall refer to the same epoch....