[Python-Dev] PEP: New timestamp formats

[Jeffrey Yasskin]

On Wed, Feb 1, 2012 at 5:03 PM, Victor Stinner
<victor.stinner at haypocalc.com> wrote:
> datetime.datetime
> -----------------
>
> datetime.datetime only supports microsecond resolution, but can be enhanced
> to support nanosecond.
>
> datetime.datetime has issues:
>
> - there is no easy way to convert it into "seconds since the epoch"

Not true:

>>> import datetime, time
>>> epoch = datetime.datetime(1970, 1, 1, 0, 0, 0)
>>> (datetime.datetime.utcnow() - epoch).total_seconds()
1328219742.385039
>>> time.time()
1328219747.640937
>>>

> - any broken-down time has issues of time stamp ordering in the
>  duplicate hour of switching from DST to normal time

Only if you insist on putting it in a timezone. Use UTC, and you should be fine.

> - time zone support is flaky-to-nonexistent in the datetime module

Why do you need time zone support for system interfaces that return
times in UTC?


I think I saw another objection that datetime represented points in
time, while functions like time.time() and os.stat() return an offset
from the epoch. This objection seems silly to me: the return value of
the system interfaces intends to represent points in time, even though
it has to be implemented as an offset since an epoch because of
limitations in C, and datetime is also implemented as an offset from
an epoch (year 0).

On the other hand, the return value of functions like time.clock() is
_not_ intended to represent an exact point in time, and so should be
either a timedelta or Decimal.

Jeffrey