[Chicken-users] Re: srfi-19 local-timezone-locale

[Kon Lovett]

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On Apr 1, 2007, at 10:14 AM, Hans Bulfone wrote:

> hi,
<snip>
> thanks!
>
> i hate to say this but it still doesn't work on my system :(
>
> should the tz offset in the tz string constructed in
> make-local-timezone-locale be east or west of utc?

Positive for west. So PST is +8:00 & CET is -1:00:

"If preceded by a (`-') the time zone shall be east of the Prime  
Meridian; otherwise it shall be west (which may be indicated by an  
optional preceding (`+'))."

But SRFI-19 uses the reverse:

"The field tm_gmtoff is the offset (in seconds) of the time  
represented from UTC, with positive values indicating east of the  
Prime Meridian."

> if i unterstand correctly, it should be west of utc,
> which is what seconds->local-time returns on my system
> (and also should return according to the docs @ callcc.org).
> so imho the sign of the timezone offset shouldn't be
> flipped on linux.
>
> imho seconds->local-time should be fixed so that it at least
> returns the timezone offset with the same sign interpretation
> on all systems.  it imho now returns seconds east of utc
> on mac os x and seconds west of utc on all other platforms.

Yes, different meaning on MacOS X from, it seems, everything else.

MacOS X:

#;2> (local-timezone-locale)
(#t (name . "XXXX+8:0:0PST+7:0:0") (source . "POSIX") (std-name .  
"XXXX") (std-offset . 28800) (dst-name . "PST") (dst-offset . 25200)  
(dst-start (4 1 0) . 3600) (dst-end (10 5 0) . 3600))
#;3> (timezone-locale-offset)
- -25200
#;4> (seconds->local-time (current-seconds))
#(56 32 12 1 3 107 0 90 #t -25200)

Windows:

#;2> (local-timezone-locale)
(#t (name . "XXXX+8:0:0XXXX+7:0:0") (source . "POSIX") (std-name .  
"XXXX") (std-offset . 28800) (dst-name . "XXXX") (dst-offset . 25200)  
(dst-start (4 1 0) . 3600) (dst-end (10 5 0) . 3600))
#;3> (timezone-locale-offset)
- -25200
#;4> (seconds->local-time (current-seconds))
#(30 7 12 1 3 107 0 90 #t 28800)

Sigh, please get 2.6.5; this is fixed.

Note that 'ftime' & 'gettimeofday' both return a positive value for  
the tz offset in minutes (i.e. west of UTC) in MacOS X. This might be  
a better x-platform source.

> felix, what do you think about this?
>
> > BTW, what does '(vector-ref (seconds->local-time (current-seconds))
> > 8)' return?
>
> #;8> (vector-ref (seconds->local-time (current-seconds)) 8)
> #t
>
> bye,
> hans.

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