[Datetime-SIG] Local time disambiguation proposal

[Chris Barker]

On Fri, Jul 31, 2015 at 8:22 AM, Alexander Walters <tritium-list at sdamon.com>
wrote:

> 1.  no one will expect the datetime module is_dst to map to the posix
> mktime function.  If they expect a mapping to the posix api, they are using
> the time module.  I think you are the only one who thought that.  Just
> because another api uses a clear term with one set of semantics, does not
> mean we cant use the clear term with a different set of semantics.
>

well, yes.

but:


> "Is this instance of time DST?  Oh, it has a member attribute 'is_dst',
> let me print that and see..."
>

this is extending the use-case of the flag -- maybe a good idea, but not
the original intent. As I understnd it the original intent is only to
disambiguate the "the same time twice" case.

"I need to tell python this time I am inputting is DST.  ...I will pass
> True to the is_dst argument"
>

why do you need to do that??? the point here is that you use the timezones
definition od DST -- you don't need to think about it, except in the
ambiguous case -- in which case, are you thining "Daylight vs Standard
Time" or "first interval, or ???

"intuitive" means "works like I expect" -- but eveyone expects different
things....

"I am in the northern hemisphere and need to construct a date in the middle
> of july.  My nation-state observes DST.  ...what the hell do i do with a
> 'first' argument?"


nothing -- there is no ambiguity in the middle of July.

-Chris

-- 

Christopher Barker, Ph.D.
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