[Datetime-SIG] Computing .dst() as a timedelta

[Alexander Belopolsky]

On Tue, Sep 22, 2015 at 8:57 PM, Chris Angelico <rosuav at gmail.com> wrote:

> [ Alexander Belopolsky] I bet people in Russia who know what

> Moscow time is outnumber those who know what UTC is at least 100 to 1.  I
> > bet you will get a similar ratio in California between UTC and say
> Eastern
> > Standard Time.
>
> Of course. Local time is always better known than UTC.


Moscow Time is hardly local for Russian Anadyr or Petropavlovsk-Kamchatsky,
but people still use Moscow Time for train schedules there.  In fact, those
places are closer to California than they are to Moscow.


> But any given local time is only going to be known in its own locality.


Depends on a locality.  Local time at the village of Greenwich is fairly
well-known. :-)


> I would bet
> that the people in Russia who know Eastern Standard Time, or the
> people in California who know Moscow time, would be quite low.
>

I suspect that anyone who knows about UTC would know about both Moscow and
New York.


> > Let's have a show of hands here: how many people know what "C" stands
> for in
> > UTC and what "M" stands in GMT and what is the significance of these
> > letters?
>
> I know, on both counts, because I'm a wonk.


Well, in this case you know more than I do.  I know that "M" stands for
"mean" (I've heard that on BBC:-) and that it has something to do with the
solar time, but I cannot tell you "mean" of what it is or whether BBC's
fifth beep comes on a UTC or GMT second.


> But those specifics are
> part of what I would elide, along with leap seconds and relativity,
> when explaining a scheduling system.


Right, but most people (myself included) only learn about UTC when they
learn about those complications.  I would say in New York, Eastern Time is
for most people, EST is for nerds and UTC is for wonks.

(Let's face it - nobody's going
> to schedule a meeting to such accuracy that any of it will matter.)
> Time is a lot messier than most people need to care about.


Right.  So let them use the time that their wall clocks are showing.  When
a New Yorker calls Cupertino, they have three options: Eastern, Pacific and
UTC.  The first two are a slight inconvenience for one of them and the
third is a major annoyance for both.
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