OK, here's a function that does precisely what I want:
def tzDelta():
"""by whatever means necessary, return the current offset of the
local time from utc."""
s=time.time()
t,u=time.localtime(s),time.gmtime(s)
osec=3600*(t[3]-u[3]) + 60*(t[4]-u[4]) + (t[5]-u[5])
return datetime.timedelta(seconds=osec)
As far as I can tell, this should always work. So wouldn't it be nice
if there were a less convoluted way to get this??
On Feb 17, 2010, at 3:12 PM, Kent Johnson wrote:
On Wed, Feb 17, 2010 at 3:48 PM, David Perlman <dperl...@wisc.edu>
wrote:
Surely there is a way to simply print out the local time, date and
time zone
without needing to write your own class... I can't believe this is
the only
way...
Here's why I don't believe it. Both the datetime and time modules
provide
both functions for returning the current local time, and the
current utc
time. So, assuming that those functions are trustworthy, it *must*
be true
that the OS always knows the current offset from utc time. So why
is there
no straightforward way to get that offset in python? I mean, I can
do this:
time.timezone gives the offset for standard time.
Kent
datetime.datetime.now()-datetime.datetime.utcnow()
datetime.timedelta(-1, 64799, 999987)
But then, of course, it's off by a few fractions of a microsecond.
This
works:
time.localtime()[3]-time.gmtime()[3]
-6
But doesn't that seem like a ridiculous hack, well outside of the
spirit of
the zen of python? Shouldn't there be one obvious right way to do
this?
Yes, I know that as William sent, the documentation points out that
the
rules the world over are complicated and irrational. Nonetheless,
it is
implicit in the existing definitions that the system *knows* the
current
offset, even if it doesn't know the whole set of rules...
On Feb 17, 2010, at 2:26 PM, Kent Johnson wrote:
On Wed, Feb 17, 2010 at 3:12 PM, David Perlman <dperl...@wisc.edu>
wrote:
Yeah, I got this part. The thing that's hanging me up is that
there
doesn't
seem to be any way to get a tzinfo instance that contains the
current
local
time zone information. You can do time.timezone to get the
seconds from
UTC, but there doesn't seem to be any way to convert that into a
tzinfo!
I
would be perfectly satisfied with this:
tz=offset_to_tzinfo(time.timezone) # or whatever
aware_now=datetime.datetime.now(tz)
print aware_now.isoformat()
I'm pretty sure that would give me what I want, but there doesn't
seem to
be
any way to do step one without subclassing tzinfo. This makes me
feel
like
I MUST be missing something obvious, because it shouldn't require
so much
coding just to find out what the current local time and timezone
is!
The docs make it clear that you do have to subclass tzinfo, that no
implementations are provided.
It sounds like you want the LocalTimezone class in the examples at
the
bottom of this section - "A class capturing the platform's idea of
local time":
http://docs.python.org/library/datetime.html#tzinfo-objects
Kent
--
-dave----------------------------------------------------------------
"Pseudo-colored pictures of a person's brain lighting up are
undoubtedly more persuasive than a pattern of squiggles produced by a
polygraph. That could be a big problem if the goal is to get to the
truth." -Dr. Steven Hyman, Harvard
--
-dave----------------------------------------------------------------
"Pseudo-colored pictures of a person's brain lighting up are
undoubtedly more persuasive than a pattern of squiggles produced by a
polygraph. That could be a big problem if the goal is to get to the
truth." -Dr. Steven Hyman, Harvard
_______________________________________________
Tutor maillist - Tutor@python.org
To unsubscribe or change subscription options:
http://mail.python.org/mailman/listinfo/tutor
