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(SRFI-19 Time/Date conversions): In default

tz-offset, note restrictions on a 32-bit system.
This commit is contained in:
Kevin Ryde 2005-01-27 23:44:05 +00:00
parent 71d0dab137
commit 702e6e093f

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@ -1718,12 +1718,23 @@ Convert between dates, times and days of the respective types. For
instance @code{time-tai->time-utc} accepts a @var{time} object of type
@code{time-tai} and returns an object of type @code{time-utc}.
For conversions to dates, @var{tz-offset} is seconds east of
Greenwich. The default is the local timezone, at the given time, as
provided by the system.
The @code{!} variants may modify their @var{time} argument to form
their return. The plain functions create a new object.
For conversions to dates, @var{tz-offset} is seconds east of
Greenwich. The default is the local timezone, at the given time, as
provided by the system, using @code{localtime} (@pxref{Time}).
On 32-bit systems, @code{localtime} is limited to a 32-bit
@code{time_t}, so a default @var{tz-offset} is only available for
times between Dec 1901 and Jan 2038. For prior dates an application
might like to use the value in 1902, though some locations have zone
changes prior to that. For future dates an application might like to
assume today's rules extend indefinitely. But for correct daylight
savings transitions it will be necessary to take an offset for the
same day and time but a year in range and which has the same starting
weekday and same leap/non-leap (to support rules like last Sunday in
October).
@end defun
@node SRFI-19 Date to string