On Sat, 13 Apr 2013, Igor Stasenko wrote:
Both #timeToRun and secondsWhenClockTicks (via Delay) using same primitive
- #millisecondClockValue.
Sure thing, precision of this primitive should be it is 1 millisecond
or smaller..
But it has nothing to do with precision of primSecondsClock and you
cannot increase precision of
it using #millisecondClockValue.
The only thing I wanted to point out is that the value of
#primSecondsClock changes when the actual second changes (the difference
is less than 1ms). So while its resolution is just 1 second, it's accuracy
is better than 1ms. Here's another example using the microsecond clock:
(1 to: 10) collect: [ :e |
| start |
Time secondsWhenClockTicks.
start := Time primUTCMicrosecondClock.
Time secondsWhenClockTicks.
Time primUTCMicrosecondClock - start ]. "==> #(1000136 999914 999961 999926
1000029 999988 999991 999985 998089 1000034)"
Because this code:
[ lastSecond = self primSecondsClock ] whileTrue: [ (Delay
forMilliseconds: 1) wait ].
actually means:
[ lastSecond = self primSecondsClock ] whileTrue: [ block not less than 1 ms ].
but not:
[ lastSecond = self primSecondsClock ] whileTrue: [ block exactly 1 ms ].
the upper bound of "(Delay forMilliseconds: 1) wait" is undefined..
and you know it well.
Of course Delays are not ideal here, but there was nothing better to use
when the code was written. As you can see in the above example, in 1 out
of 10 cases the difference was less than 999 ms.
Levente
About DateAndTime: having it nanosecond resolution is a future proof idea.
It will take a while till software can create better accuracy timestamps.
Reducing the resolution to milliseconds is a very bad idea. The VM and
external software can give you a microsecond or smaller resolution timestamp
which you want to represent as DateAndTime (or whatever class you use to
create a timestamp) in the image.
Yes i know. My problem is the amount of code which does something
"userful" with nanoseconds
while everybody knows that we have no such resolution.. and won't have
in 10 years or so.
Levente
--
Best regards,
Igor Stasenko.
