Re: [PATCH 3/3] gitk: Allow displaying time zones from author and commit timestamps

On Sun, May 29, 2011 at 10:35:08PM -0700, Jakub Narebski wrote:

Anders Kaseorg [off-list ref] writes:

quoted

On Sun, 29 May 2011, Paul Mackerras wrote:

quoted

quoted

quoted

@@ -11018,7 +11018,18 @@ proc prefsok {} {
 proc formatdate {d} {
     global datetimeformat
     if {$d ne {}} {
-	set d [clock format [lindex $d 0] -format $datetimeformat]
+	if {[string match {*%[zZ]*} $datetimeformat]} {
+	    if {[catch {set d [clock format [lindex $d 0] -timezone [lindex $d 1] -format $datetimeformat]}]} {
+		# Tcl < 8.5 does not support -timezone.
+		global env
+		set zone [lindex $d 1]
+		set env(TZ) "IDK[string range $zone 0 2]:[string range $zone 3 end]"

What is this about?  Where is the IDK prefix for timezones defined or
described?

Yeah, sorry, that deserved a bit more explanation.  This is a kludge to 
get Tcl 8.4 to format dates in the right timezone.  IDK is an arbitrary 
made up 3-letter code (“I Don’t Know”), since a UTC offset can’t generally 
be converted into a zone name.  The format of TZ is described at:
http://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html
http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html

Actually, reading that again, I just realized that I need to invert the 
sign.  Also that it can be longer than 3 letters; I’ll use “Unknown” 
instead.

Why not use UTC+N timezone (note: please check of for +HHMM it is
UTC+HH or UTC-HH) for timezone with given numeric offset from
Coordinated Universal Time?

BTW. UTC because http://www.nist.gov/pml/div688/utcnist.cfm#cut

But what of half-hour offsets, in that case?  A better idea would be
UTC+HHMM or UTC-HHMM.  As an example, SA (CST) has a timezone of
UTC+0930.


Tim

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