[Python-Dev] Status on PEP-431 Timezones

[Ryan Hiebert]

> On Jul 27, 2015, at 9:13 AM, Steven D'Aprano <steve at pearwood.info> wrote:
> 
> On Mon, Jul 27, 2015 at 10:54:02AM +0200, Lennart Regebro wrote:
>> On Mon, Jul 27, 2015 at 10:47 AM, Paul Moore <p.f.moore at gmail.com> wrote:
>>> I'm confused by your position. If it's 7am on the clock behind me,
>>> right now, then how (under the model proposed by the PEP) do I find
>>> the datetime value where it will next be 7am on the clock?
>> 
>> PEP-431 does not propose to implement calendar operations, and hence
>> does not address that question.
> 
> To me, Paul's example is a datetime operation: you start with a datetime 
> (7am today), perform arithmetic on it by adding a period of time (one 
> day), and get a datetime as the result (7am tomorrow).
> 
> To my naive mind, I would have thought of calendar operations to be 
> things like:
> 
> - print a calendar;
> - add or remove an appointment;
> - send, accept or decline an invitation
> 
> What do you think calendar operations are, and how do they differ from 
> datetime operations? And most importantly, how can we tell them apart?

The way I interpreted it is that "calendar operations" require knowledge of events like daylight savings time that require a more complete knowledge of the calendar, rather than just a naive notion of what a date and time are.