[Python-Dev] PEP: New timestamp formats

[Antoine Pitrou]

On Fri, 3 Feb 2012 11:04:14 -0800
Jeffrey Yasskin <jyasskin at gmail.com> wrote:
> On Thu, Feb 2, 2012 at 4:59 PM, Nick Coghlan <ncoghlan at gmail.com> wrote:
> > datetime.datetime
> >
> > - real problem with the idea is that not all timestamps can be easily
> > made absolute (e.g. some APIs may return "time since system started"
> > or "time since process started")
> 
> I think this is an argument for returning the appropriate one of
> datetime or timedelta from all of these functions: users need to keep
> track of whether they've got an absolute time, or an offset from an
> unspecified starting point, and that's a type-like distinction.

Keep in mind timedelta has a microsecond resolution. The use cases
meant for the PEP imply nanosecond resolution (POSIX' clock_gettime(),
for example).

> A plain number of seconds is superficially simpler, but it forces more
> complexity onto the user, who has to track what that number
> represents.

If all you are doing is comparing timestamps (which I guess is most of
what people do with e.g. st_mtime), a number is fine.

If you want the current time and date in a high-level form, you can
already use datetime.now() or datetime.utcnow() (which "only" has
microsecond resolution as well :-)). We don't need another way to spell
it.

Regards

Antoine.