Re: Time zone and 'lapsed under NT

[Toby Speight <Toby.Speight@streapadair.freeserve.co.uk>]

Lars> Lars Magne Ingebrigtsen <URL:mailto:larsi@gnus.org>

0> Toby Speight <Toby.Speight@streapadair.freeserve.co.uk> writes:

>> The Emacs documentation doesn't describe (current-time) very well.  It
>> says, "the current time, as the number of seconds since 1970-01-01
>> 00:00:00" - without specifying a time zone for that epoch...


0> In <URL:news:m3vhbtfsh5.fsf@quimbies.gnus.org>, Lars wrote:

Lars> (current-time-string (current-time))
Lars> => "Fri Jul  9 22:59:05 1999"
Lars>
Lars> which is the local time, here, now.  (After fixing the clock.)

(current-time)
=> (14218 11870 732000)
(current-time-string '(14218 11870 732000))
=> "Mon Jul 12 19:05:18 1999"

That's local time for me, too (on NT).  What I'm not sure about is
whether the representation of (current-time) is the same on both
platforms; it's possible that it is seconds-after-local-epoch on one
platform and seconds-after-UT-epoch on the other.  If
(current-time-string) matches, you'd only see the difference if (a)
you transfer numeric times between the platforms or (b) you build a
numeric time from something other than (current-time).  We're doing
(b).  Just a theory.  Can you report what (current-time-string '(14218
11870 732000)) gives you?


Lars> But what am I getting at?  Uhm -- perhaps the bug isn't in the
Lars> generating-the-Data-header part, but in the parsing part?

I think perhaps it is:

(date-to-time "Thu, 01 Jan 1970 02:00:00 GMT")
=> (0 7200)
(date-to-time "Thu, 01 Jan 1970 02:00:00 EST")
=> (0 7200)

but:

(parse-time-string "Thu, 01 Jan 1970 02:00:00 GMT")
=> (0 0 2 1 1 1970 4 (0) 0)
(parse-time-string "Thu, 01 Jan 1970 02:00:00 EST")
=> (0 0 2 1 1 1970 4 (-18000) -18000)

So I suspect date-to-time, which is basically a wrapper around
encode-time.  encode-time is a built-in function, so if this is
broken, it's an NTEmacs bug.  BTW, I'm on GNU Emacs 20.3.1
(i386-*-nt4.0).  Checking:

(encode-time 0 0 2 1 1 1970 4 '(0) 0)
=> (0 7200)
(encode-time 0 0 2 1 1 1970 4 '(-18000) -18000)
=> (0 7200)

Looks like that's our bug.  A workaround ought to be possible, but
only by duplicating the broken functions.  I don't have the time to do
it.

P.S. Lars, could you report this to the Emacs bug team?  Ta.  I guess
you'd better include the associated documentation bug (what zone is
the epoch?), too.