There's a problem with Mike's low-res-time function:
fun rfc1123_date (dt:&tm) => strftime("%a, %d %b %Y %H:%M:%S %Z",dt);
because it uses the %Z specifier and strftime. The result of strftime
and localtime() functions are indeterminate.
My rough view is: local times should never be used.
Time zone names also shouldn't be used.
Instead, the only permitted timezones should be:
UTC
UTC+0230
UTC-0600
i.e. UTC, or UTC+/- 4 digits represent 24 hour clock format offset.
A time without a zone should be considered to mean UTC.
A time for a local timezone can be easily adjusted to UTC this way.
GMT is not a time standard.
The strftime function should never be used with %Z,
because the time zone is indeterminate. See Posix standard.
In the actual test code, we get a failure because we start with an
absolute (GMT) time, parse it into a tm_ structure thing, and in
doing so the timezone is lost. Then strftime goes and puts in
the local timezone.
I've annoyed Mike by changing the *.expect to what my Mac says:
it says the AEDST time is "EST" which is also wrong. EST means
American Eastern Standard Time. AEST is for Australia.
I have no idea what Sydney DST is called (note QLD doesn't use
daylight saving, so it's always AEST).
We need to figure a way to handle this. We need to ensure somehow,
possibly using the type system, that *standard* time values, which means
UTC or Posix time don't get mixed up with local times.
This is also critical for file times (as in fstat etc).
The "defacto" Felix standard for times is
type: double
base: Posix (1 Jan 1970)
unit: seconds
Anything that muddles with tm_ struct should be private, to prevent the user
getting at it.
I'd rather see Felix provide it's own sane functions than use the rubbish
in C/Posix. Of course we have to make *string* times which are compliant
with network standards.
--
john skaller
skal...@users.sourceforge.net
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