[Python-ideas] Reduce platform dependence of date and time related functions

M.-A. Lemburg mal at egenix.com
Wed Sep 18 15:34:31 CEST 2013

On 18.09.2013 15:25, random832 at fastmail.us wrote:
> On Wed, Sep 18, 2013, at 3:42, M.-A. Lemburg wrote:
>> I wonder why you'd want to use Unix ticks (what datetime calls a
>> timestamp) as basis for cross-platform date/time calculations.
> Because we've already got half a dozen APIs that use them. And there's
> no particular reason to consider it _worse_ than any other scalar time
> representation.
> If we were defining the library from scratch today, we could argue the
> merits of using days vs seconds vs microseconds as the unit, of 1970 vs
> 1904 vs 1600 vs 0000 for the epoch, and whether leap seconds should be
> supported. But we've already got APIs that use time_t (and all supported
> platforms define time_t as seconds since 1970)

Right, but those APIs are all limited to what the platforms
defines as t_time and like you say: those values are often
limited to certain ranges.

If you want platform independent representations, use one of the
available conversion routines to turn the time_t values into
e.g. datetime objects and ideally convert the values to UTC
to avoid time zone issues. Then use those objects for date/time

time_t values are really not a good basis for doing date/time
calculations. Ideally, they should only be used and regarded
as containers holding a platform dependent date/time value,
nothing more.

Marc-Andre Lemburg

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