[Python-Dev] Status on PEP-431 Timezones

Chris Angelico rosuav at gmail.com
Tue Jul 28 19:25:57 CEST 2015


> On Tue, Jul 28, 2015 at 3:22 AM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
> To me a day is precisely 24 hours, no more, no less.

Start with this line. Then proceed:

On Wed, Jul 29, 2015 at 3:01 AM, Mark Lawrence <breamoreboy at yahoo.co.uk> wrote:
> My cashflow forecast doesn't give two hoots how many hours there are in two
> weeks, which I've defined elsewhere.  It doesn't care if the time changes.
> Neither does it care how many days there are in a month for that matter.  It
> can even cater with plotting data with a tick on the 29th of each month when
> we have a leap year and February is included in the plot, thanks to the
> dateutils rrule.

Okay. So you do *not* care that a day be, or not be, 24 hours. Your
code cares about days, and does not care if one of them happens to be
23 or 25 hours long. That's what's going on. To you, a day is *one
day*, and has no correlation to 24 hours, 86400 seconds, 86,400,000
milliseconds, or the radiation period of caesium. That's a perfectly
acceptable standpoint, but you MUST acknowledge that this is
incompatible with the equally-acceptable standpoint that "1 day" ==
"24 hours". You cannot have both.

ChrisA


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