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Timezones

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  Timezones Seymore4Head <Seymore4Head@Hotmail.invalid> - 2014-10-05 17:17 -0400
    Re: Timezones Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-10-05 23:15 +0100
      Re: Timezones Rustom Mody <rustompmody@gmail.com> - 2014-10-05 19:37 -0700
        Re: Timezones Chris Angelico <rosuav@gmail.com> - 2014-10-06 13:48 +1100
          Re: Timezones Seymore4Head <Seymore4Head@Hotmail.invalid> - 2014-10-07 17:26 -0400
    Re: Timezones Akira Li <4kir4.1i@gmail.com> - 2014-10-06 05:10 +0400

#78724 — Timezones

This is not a new video, but it is new to me.
https://www.youtube.com/watch?v=-5wpm-gesOY

Any links to some easy to follow time zone math?

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#78725

On 05/10/2014 22:17, Seymore4Head wrote:
> This is not a new video, but it is new to me.
> https://www.youtube.com/watch?v=-5wpm-gesOY
>
> Any links to some easy to follow time zone math?
>

My advice is to avoid time zones, they're a real pain, seriously.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence

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#78735

On Monday, October 6, 2014 3:45:44 AM UTC+5:30, Mark Lawrence wrote:
> On 05/10/2014 22:17, Seymore4Head wrote:
> > This is not a new video, but it is new to me.
> > https://www.youtube.com/watch?v=-5wpm-gesOY
> > Any links to some easy to follow time zone math?

> My advice is to avoid time zones, they're a real pain, seriously.

What say we send an application to the UN to declare the world flat?

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#78737

On Mon, Oct 6, 2014 at 1:37 PM, Rustom Mody <rustompmody@gmail.com> wrote:
>> My advice is to avoid time zones, they're a real pain, seriously.
>
> What say we send an application to the UN to declare the world flat?

Easier to simply start scheduling things in UTC. I run an
international Dungeons & Dragons campaign with sessions every Sunday
at 02:00 UTC, and nobody needs to be confused by time zones. (The
server displays UTC time, so it's easy for anyone to see; for
instance, it's now Mon 02:48:09, so session time was about this time
yesterday.) Civil time can do whatever it likes, just as long as
everyone knows that the meeting is based on UTC.

ChrisA

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#78812

On Mon, 6 Oct 2014 13:48:58 +1100, Chris Angelico <rosuav@gmail.com>
wrote:

>On Mon, Oct 6, 2014 at 1:37 PM, Rustom Mody <rustompmody@gmail.com> wrote:
>>> My advice is to avoid time zones, they're a real pain, seriously.
>>
>> What say we send an application to the UN to declare the world flat?
>
>Easier to simply start scheduling things in UTC. I run an
>international Dungeons & Dragons campaign with sessions every Sunday
>at 02:00 UTC, and nobody needs to be confused by time zones. (The
>server displays UTC time, so it's easy for anyone to see; for
>instance, it's now Mon 02:48:09, so session time was about this time
>yesterday.) Civil time can do whatever it likes, just as long as
>everyone knows that the meeting is based on UTC.
>
>ChrisA

And I just found out there is going to be another Y2K in 2038.  I hope
I am around to see it.  I spend this Y2K in Las Vegas.

Las Vegas is one of the last few time zones so TVs everywhere were
showing the ringing in of the New Year and nothing was exploding.

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#78733

Seymore4Head <Seymore4Head@Hotmail.invalid> writes:

> This is not a new video, but it is new to me.
> https://www.youtube.com/watch?v=-5wpm-gesOY
>
> Any links to some easy to follow time zone math?

The point of the video is that you should not do it yourself, use
already written tools.

It is quite comprehensive video. Here's how the mentioned issues could
be resolved:

- erratic UTC offset changes by politicians in different countries --
  *use UTC timezone* for calculations, in addition (if necessary) store
  both the local time and timezone info. *Use pytz module* that provides
  access to the tz database to convert between timezones (many people
  get it wrong but it is not a rocket science). As said in the video, it
  won't help if the rules change a day before the DST transition but at
  least most [1] systems will be consistent. It also doesn't support
  some exotic timezone rules such as in Saudi Arabia (sunrise and/or
  sunset at the fixed local time every day [2]) or many timezones before
  1970.

- julian, gregorian calendars, proleptic UT (past dates): *use proleptic
  gregorian calendar (datetime module)* unless you know that you need
  otherwise (then you could investigate what JD means in a particular
  document given multiple possible interpretations)

- leap seconds (posix, Mills, Windows(ntp), smear (google, java)),
  "right" timezones, and the difference between UT1, UTC(BIMP), GPS,
  TT(TAI), TCB, etc time scales: *ignore them* unless you know that you
  need otherwise e.g., legally elapsed seconds [3]. Here's some pictures
  to illustrate the difference between time scales [4].

[1] http://www.iana.org/time-zones/repository/tz-link.html
[2] https://github.com/eggert/tz/blob/master/asia#L2439
[3] http://www.ucolick.org/~sla/leapsecs/epochtime.html
[4] http://www.ucolick.org/~sla/leapsecs/deltat.html


--
Akira

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