DateTime stftime and TAI based timezone is broken or is it?
Yesterday I switched my Linux machines to use clockspeed 0.62 and therefore had to switch to the right/EST5EDT timezone. Today my client calls rather upset that lots of data has disappeared from his database, etc.. So while I have found and fixed a bunch of timezone conversion problems in my code, I'm stumped by DateTime.strftime(). I'm working with Zope 2.6.0 but the code is the same in 2.7.0b2 Basically, I get this situation:
dx '2003-12-01 00:00:00' y = DateTime.DateTime(dx) y DateTime('2003/12/01') y.strftime("%a %b. %d") 'Sun Nov. 30' y.strftime("%a %b %d %H:%M:%S") 'Sun Nov 30 23:59:38' y.Time() '00:00:00'
So, the DateTime object knows the correct year, month and day, it's mishandling of 'diff' in strftime is a problem. I can't quite figure out what the regex does in the code below, but diff is 22 seconds off from the "regular timezone offset". That's will be lost in the divide by 36. The timezone offset that _tzoffset calculates is wrong:
DateTime._tzoffset(y._tz, y._t) -18000
Because
y._tz 'US/Eastern'
(but it should be 'right/EST5EDT') What's the best way for me to fix this? I'll submit a patch if I can get a clue. Btw, the timezone right/EST5EDT isn't in DateTime's timezone listing. Shouldn't Zope get this data from Python? I'll remark that Python doesn't know about the 'correct' offset either.
import time time.tzname ('EST', 'EDT') time.timezone 18000
Well now I'm stuck, I've set /etc/localtime and /usr/share/zoneinfo/posixrules correctly, and "date" returns the correct time. However even forcing TZ with Python 2.3 doesn't work correctly. sh-2.05b$ TZ="right/EST5EDT" python2.3 Python 2.3.2 (#2, Nov 6 2003, 10:44:39) [GCC 3.2.2 20030222 (Red Hat Linux 3.2.2-5)] on linux2 Type "help", "copyright", "credits" or "license" for more information.
import os os.environ['TZ'] 'right/EST5EDT' import time time.timezone 18000 time.tzname ('EST', 'EDT') time.tzset() time.tzname ('EST', 'EDT') time.timezone 18000
How does time.localtime() know the correct timezone offset, but time.timezone is not correct?
time.localtime(); os.system('date') (2003, 12, 1, 12, 55, 25, 0, 335, 0) Mon Dec 1 12:55:25 EST 2003
----- DateTime.py def strftime(self, format): # Format the date/time using the *current timezone representation*. diff = _tzoffset(self._tz, self._t) format = re.sub('(^\|[^%])%z', '\\1%+05d' % (diff / 36), format) return strftime(format, safegmtime(self.timeTime() + diff)) -- Brad Clements, bkc@murkworks.com (315)268-1000 http://www.murkworks.com (315)268-9812 Fax http://www.wecanstopspam.org/ AOL-IM: BKClements
Brad Clements wrote:
Yesterday I switched my Linux machines to use clockspeed 0.62 and therefore had to switch to the right/EST5EDT timezone.
Today my client calls rather upset that lots of data has disappeared from his database, etc..
Interesting, I've been using right/US/Pacific myself for ages but I never experienced any pain from it. Then again, I never noticed DateTime was getting stuff wrong until you pointed this out.
y = DateTime.DateTime(dx) y DateTime('2003/12/01') y.strftime("%a %b. %d") 'Sun Nov. 30' y.strftime("%a %b %d %H:%M:%S") 'Sun Nov 30 23:59:38'
Lovely. Its always bugged me that DateTime carried all its own zone information, but I guess even the datetime python modules punt in this regard. What I'm currious to know is how this caused problems for you, or your clients. I'd like to avoid those problems myself if I can help it. -- Jamie Heilman http://audible.transient.net/~jamie/ "Paranoia is a disease unto itself, and may I add, the person standing next to you may not be who they appear to be, so take precaution." -Sathington Willoughby
On 2 Dec 2003 at 13:39, Jamie Heilman wrote:
y = DateTime.DateTime(dx) y DateTime('2003/12/01') y.strftime("%a %b. %d") 'Sun Nov. 30' y.strftime("%a %b %d %H:%M:%S") 'Sun Nov 30 23:59:38'
Lovely. Its always bugged me that DateTime carried all its own zone information, but I guess even the datetime python modules punt in this regard. What I'm currious to know is how this caused problems for you, or your clients. I'd like to avoid those problems myself if I can help it.
My legacy site has a lot of <dtml-var somedatetimeobject fmt="%a %b %d"> this writes out the wrong day, because somedatetimeobject is just like you show above. Also, I get different results instantiating a DateTime object with a string, vs. parts DateTime(y,m,d,h,m,s) vs. DateTime('YYYY-MM-DD HH:MM:SS') Why can't Zope just dynamically load the tzfile data as appropriate from the system if it can? -- Brad Clements, bkc@murkworks.com (315)268-1000 http://www.murkworks.com (315)268-9812 Fax http://www.wecanstopspam.org/ AOL-IM: BKClements
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