[Python-Dev] Epoch and Platform

[Guido van Rossum]

Leap seconds? Leap seconds aren't supposed to exist when looking at
POSIX timestamps. They don't exist when I look at my watch either, and
that's what I expect from any time-keeping device except those for use
by astronomers.

On Wed, Jun 18, 2008 at 2:50 AM, Pete Forman
<pete.forman at westerngeco.com> wrote:
> "Guido van Rossum" <guido at python.org> writes:
>  > On Tue, Jun 17, 2008 at 11:09 AM, Curt Hagenlocher
>  > <curt at hagenlocher.org> wrote:
>>> On Tue, Jun 17, 2008 at 10:56 AM, Guido van Rossum
>>> <guido at python.org> wrote:
>>>> On Tue, Jun 17, 2008 at 10:40 AM, Curt Hagenlocher
>>>> <curt at hagenlocher.org> wrote:
>>>>>
>>>>> There's no real urgency.  The reason this came up is because I
>>>>> just implemented zlib, which automatically enabled the gzip unit
>>>>> tests.  The gzip tests are failing because the current timestamp
>>>>> can't be written as a 32-bit value.
>>>>
>>>> Why is that? Is it because your epoch is different? If so, I would
>>>> much prefer the epoch to be 1970. (Maybe this is the resolution
>>>> you're seeking?)
>>>
>>> Yes!  Except that I was hoping for something a little stronger, like
>>> "the epoch must be 1970" or "the epoch can be anything you want, but
>>> you're utterly retarded if you pick something other than 1970".  But
>>> I'll definitely settle for "much prefer". :)
>>
>  > I could go with the "utterly retarded" wording. :-)
>
> The POSIX (UNIX) rules for handling time are laid out clearly.  Not
> everyone is happy with how leap seconds work but at least they can be
> dealt with by those who need to.  Most people will use local time or
> UTC and other time scales are possible with a bit of effort.  If you
> were to allow an epoch earlier than 1970 then ambiguity is more likely
> to sneak in.
>
> Another reason not to allow an epoch of 1900 is that Microsoft
> introduced a bug in its leap year algorithm in Excel.  The better
> (less bad) way of using that epoch is to propagate that bug.
>
> According to the Pythonic way you should not have to look before you
> leap.  ;-)
>
> +1 for strengthening the definition of epoch in the time module to
> 1970-01-01T00:00:00Z for all platforms.
> --
> Pete Forman                -./\.-  Disclaimer: This post is originated
> WesternGeco                  -./\.-   by myself and does not represent
> pete.forman at westerngeco.com    -./\.-   the opinion of Schlumberger or
> http://petef.22web.net           -./\.-   WesternGeco.
>
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-- 
--Guido van Rossum (home page: http://www.python.org/~guido/)