problem with "time"

[a_geek]

Hello,

I'm writing a small program that needs to check Unix timestamps for
falling into an interval (typical usage: ./program 2005-03, you get
the idea). Now, I create two time stamps from the user's input to
create the interval's borders using mktime(). Trying to check the sanity
of my program, I also converted the values back to tuples using
localtime(). Unfortunately, I get back one of them with the DST flag
set, and the other with the DST flag unset.

I have _no_ idea on how localtime() could reasonably synthesize
different values for that flag for _any_ time value converted in about
the same millisecond. What gives?

Thank you!

 

[Jeff Epler]

Without your code, it's hard to tell.

Here's a small program I wrote:
import time

t = time.time()
print time.localtime(t - 86400)
print time.localtime(t)
on both lines, the tm_isdst flag is the same.

If I choose two times that are on either side of the DST change in
my timezone, I get different answers:
import time

t = time.time()
print time.localtime(t)
print time.localtime(t+86400 * 90)
Here, I get different values for tm_isdst because DST is in effect for
one of the times but not the other.

I have _no_ idea on how localtime() could reasonably synthesize
different values for that flag for _any_ time value converted in about
the same millisecond. What gives?

The tm_isdst field is not about the DSTness at the time of
conversion---it's about the DSTness of the converted time.

Jeff

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