On Mon, Jul 27, 2015 at 12:15 PM, Nikolaus Rath <Nikolaus@rath.org> wrote:
On Jul 27 2015, Lennart Regebro <regebro@gmail.com> wrote:
> That you add one hour to it, and the datetime moves forward one hour
> in actual time? That's doable, but during certain circumstance this
> may mean that you go from 1AM to 1AM, or from 1AM to 3AM.
>
> Or do you expect that adding one hour will increase the hour count
> with one, ie that the "wall time" increases with one hour? This may
> actually leave you with a datetime that does not exist, so that is not
> something you can consistently do.

Apologies for asking yet another dumb question about this, but I have
the impression that a lot of other people are struggling with the basics
here too.

I believe your questions are addressed to Lennart, but let me offer
my answer to the first:

Can you tell us which of the two operations datetime currently
implements?

The first one, but not as directly as one might wish.  (I think the situation
is similar to that of pytz's normalize(), but I am not an expert on pytz.)

>>> t = datetime(2014,11,2,5,tzinfo=timezone.utc).astimezone()
>>> t.strftime("%D %T%z %Z")
'11/02/14 01:00:00-0400 EDT'
>>> (t+timedelta(hours=1)).astimezone().strftime("%D %T%z %Z")
'11/02/14 01:00:00-0500 EST'