[Python-Dev] Time since the epoch

[Thomas Wouters]

On 5/2/06, Sanghyeon Seo <sanxiyn at gmail.com> wrote:
>
> Hello,
>
> Python library reference 6.11 says, "The epoch is the point where the
> time starts. On January 1st of that year, at 0 hours, the "time since
> the epoch'' is zero. For Unix, the epoch is 1970."
>
> To me this seems to suggest that the epoch may vary among platforms
> and implementations as long as it's consistent. Am I correct?


Yes. (I believe the C standard doesn't specify the 'epoch', just POSIX does
-- for C. Regardless of that, Python's 'epoch' isn't guaranteed anywhere,
and the docs you quote are probably the most authorative docs on the
question.)

For example, does it make sense to file bug reports to Python projects
> assuming that time.time() returns seconds since the Unix epoch?


I would say so, yes.

I am asking because currently Python and IronPython returns very
> different values for time.time() even if they run on the same computer
> and at the same time.


As long as the value returned by time.time() is still 'seconds', and
everything in the time and datetime modules properly considers the same
epoch, I would say it's a bug (for third-party modules or for other parts of
the standard library) to break.

--
Thomas Wouters <thomas at python.org>

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