🚀 go-pugleaf

I have been perusing the DWP and have found nothing added to the Standard
C Library for coping with times, in particular a method for computing a
new time by adding an offset to a known time or finding the difference
between two times.

The standard mktime() almost does this well already. The fact that a
"suitable" method already exists is probably why nothing was added to the
standard. However, string<> was added to standardize the many differing
implementations of strings. Lots of vendors provide a custom date/time
object too; why were these classes not also standardized?

The particular problem I run into has to do with daylight savings time. In
places where DST is an issue, there's typically one day of the year that
has two ranges of time from 1am to 2am and another day of the year where
that time range doesn't exist. The standard doesn't seem to address this
issue well. Suppose I use mktime() to create "The first Sunday in April at
1:30am"? Where I live, that time doesn't exist. What does mktime() create?
Or "The first Sunday in November at 1:30am"? Where I live, there are two
possible interpretations of that.

Even worse, suppose I have a struct tm containing "The day before daylight
savings time begins at 12pm." When I add 24 hours to tm_hours and set
tm_isdst to -1, what does mktime() create? The next day at 12pm, 1pm, or
11am? Daylight savings time or not? Which semantics I want probably
depends on whether I'm trying to calculate "1 day from now" or "24 hours
from now."

There has to be some reasonable answer to these questions; why doesn't the
standard address it? Or am I just missing something?

--
Bradd W. Szonye
Doubleplus Corporation
bradds@ix.netcom.com



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