[Python-ideas] lack of time zone support

Bill Janssen janssen at parc.com
Tue Jun 1 20:32:34 CEST 2010

To me, the single most irritating problem with the Python support for
date/time is the lack of support for time-zone understanding.  This
breaks down into two major issues, %z and lack of a standard time-zone

First, let's say I have to parse a Medusa log file, which contains time
stamps in the form "DD/Mon/YYYY:HH:MM:SS [+|-]HHMM", e.g.
"31/May/2010:07:10:04 -0800".  What I'd like to write is

  tm = time.mktime(time.strptime(timestamp, "%d/%b/%Y:%H:%M:%S %z"))

which is what I'd do if I was writing in C.  But no!  The Python
_strptime module doesn't support "%z".  So instead, I have to pick the
timestamp apart and do things separately and remember that "-0800" isn't
octal, and also isn't the same as -800, and remember whether to add or
subtract it.  This seems insane.  So, IMO, support for %z should be
added to Lib/_strptime.py.  We need a patch.

Secondly, we really need concrete subclasses of tzinfo, and some sort of
mapping.  Lots of people have spent lots of time trying to figure out
this cryptic hint in datetime: "The datetime module does not supply any
concrete subclasses of tzinfo."  I'm not sure whether pytz is the best
ideas, or what I use, the "zoneinfo" module from python-dateutil.  With
that, I still have to add the Windows timezone names, using the table at
because the code in python-dateutil only works with Windows timezone
names when running on Windows.


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