[Python-ideas] Date/time literals

[Alexander Belopolsky]

On Tue, Jun 1, 2010 at 10:41 AM, Mark Dickinson <dickinsm at gmail.com> wrote:
..
> As per the POSIX standard (IIUC), [datetime(1985, 6, 30, 23, 59, 60)] would be
> immediately converted
> to datetime.datetime(1985, 7, 1, 0, 0, 0) internally.  So the datetime
> object itself wouldn't support leap seconds, and would continue to use
> POSIX time;  only the constructor would support leap seconds.
>

It is my understanding that POSIX mandates that mktime() function
normalizes the tm structure and therefore converts (1985, 6, 30, 23,
59, 60, ...) to (1985, 7, 1, 0, 0, 0, ...).  It is not quite accurate
to say that tm structure is converted "immediately".  It is perfectly
legal to pass around non-normalized tm structures and have for example
utc2gps() function that would produce different values for Y-M-D
23:59:60 and T-M-[D+1] 00:00:00.

I would prefer a similar behavior for datetime constructor:

>>> datetime(1985, 6, 30, 23, 59, 60).second
60
>>> datetime(1985, 6, 30, 23, 59, 60).timetuple()
(1985, 6, 30, 23, 59, 60, ...)

but
>>> datetime(1985, 6, 30, 23, 59, 60) - datetime(1985, 7, 1, 0, 0, 0)
datetime.timedelta(0)