[MacPerl-Porters] MacPerl daylight saving time issue

Hi,

to make a long story short: In the past, I have sent some Mac OS 
patches to Steffen Beyer for his Date::Calc module. He just released 
Date::Calc 5.1, which is basically version 5.0 plus Mac OS Classic 
support. While running the module tests for a pre-release version, I 
noticed 3 failures, all related to the daylight saving time flag. 
$dst is 0 for winter time, and 1 for summer time (and -1 if not 
supported). Said tests check if $dst == 0 for a given date and fail. 
My Mac is currently set to summer time, hence I first thought that 
$dst is correctly set to 1. But Steffen reminded me, that on Unix, 
Windows etc. the daylight saving time flag is set according to the 
given date. For instance, on December 24th, 2001, $dst should be 0 
(see the sample script below), right? But obviously, if a Mac is set 
to summer time, and I check the Christmas Eve date, $dst will be 1 
(!). My conclusion: $dst depends on the Date&Time control panel 
setting, and not on a given date. I won't say this is a bug, but it 
is, isn't it? :-)

I am confused, to be honest. Is this a known issue (in GUSI, I 
think), or a bug in my brain? Ideas?



#!perl -w

use Time::Local;

$time = timelocal(0, 0, 12, 24, 11, 2001); # Dec 24th, 2001 12:00:00


($sec,$min,$hour,$day,$month,$year,$dow,$doy, $dst) = localtime( $time );

$year += 1900;
$month += 1;

print "year= $year\n";
print "month = $month\n";
print "day = $day\n";
print "hour = $hour\n";
print "min = $min\n";
print "sec = $sec\n";
print "doy = $doy\n";
print "dow = $dow\n";
print "dst = $dst\n";

__END__

Result:

year= 2001
month = 12
day = 24
hour = 12
min = 0
sec = 0
doy = 357
dow = 1
dst = 1 # daylight saving time, should be 0 on Dec 24th, 2001 ???



Regards,

Thomas.