bug#45608: 28.0.50; calendar-iso-date-string: "Day 6 of week 53 of 2020"

bug#45608: 28.0.50; calendar-iso-date-string: "Day 6 of week 53 of 2020"

[Jean Louis]

(calendar-iso-date-string) gives following information on this day:
"Day 6 of week 53 of 2020" which I consider wrong as it is 2021 and
the year has 52 weeks normally, the days at begin of the new year
should not be considered past year.





In GNU Emacs 28.0.50 (build 4, x86_64-pc-linux-gnu, X toolkit, cairo version 1.14.8, Xaw3d scroll bars)
 of 2021-01-01 built on protected.rcdrun.com
Repository revision: 30a1d5da7a43d51a97cbe8d91add9a26dd99df90
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.11907000
System Description: Hyperbola GNU/Linux-libre

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Major mode: Lisp Interaction


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-- 
Thanks,
Jean Louis
⎔ λ 🄯 𝍄 𝌡 𝌚

bug#45608: 28.0.50; calendar-iso-date-string: "Day 6 of week 53 of 2020"

[Alan Third]

On Sat, Jan 02, 2021 at 12:03:16PM +0100, Jean Louis wrote:
> 
> (calendar-iso-date-string) gives following information on this day:
> "Day 6 of week 53 of 2020" which I consider wrong as it is 2021 and
> the year has 52 weeks normally, the days at begin of the new year
> should not be considered past year.

You'd best take that up with ISO, as this is how ISO dates work.

-- 
Alan Third

bug#45608: 28.0.50; calendar-iso-date-string: "Day 6 of week 53 of 2020"

[Lars Ingebrigtsen]

Jean Louis <bugs@gnu.support> writes:

> (calendar-iso-date-string) gives following information on this day:
> "Day 6 of week 53 of 2020" which I consider wrong as it is 2021 and
> the year has 52 weeks normally, the days at begin of the new year
> should not be considered past year.

https://en.wikipedia.org/wiki/ISO_week_date

"An ISO week-numbering year (also called ISO year informally) has 52 or
53 full weeks. That is 364 or 371 days instead of the usual 365 or 366
days. The extra week is sometimes referred to as a leap week, although
ISO 8601 does not use this term. Weeks start with Monday. Each week's
year is the Gregorian year in which the Thursday falls. The first week
of the year, hence, always contains 4 January. ISO week year numbering
therefore slightly deviates from the Gregorian for some days close to 1
January."

Closing.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#45608: 28.0.50; calendar-iso-date-string: "Day 6 of week 53 of 2020"

[Eli Zaretskii]

> Date: Sat, 02 Jan 2021 12:03:16 +0100
> From: Jean Louis <bugs@gnu.support>
> 
> (calendar-iso-date-string) gives following information on this day:
> "Day 6 of week 53 of 2020" which I consider wrong as it is 2021 and
> the year has 52 weeks normally, the days at begin of the new year
> should not be considered past year.

When a week starts in year Y and ends in year Y+1, what would you want
to see instead?  Saying "week 1 of 2021" would be wrong for the same
reason.

bug#45608: 28.0.50; calendar-iso-date-string: "Day 6 of week 53 of 2020"

[Andreas Schwab]

On Jan 02 2021, Jean Louis wrote:

> the year has 52 weeks normally

That is not possible, as 52 weeks can only cover 364 days.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."

bug#45608: 28.0.50; calendar-iso-date-string: "Day 6 of week 53 of 2020"

[Drew Adams]

> > (calendar-iso-date-string) gives following information on this day:
> > "Day 6 of week 53 of 2020" which I consider wrong as it is 2021 and
> > the year has 52 weeks normally, the days at begin of the new year
> > should not be considered past year.
> 
> https://urldefense.com/v3/__https://en.wikipedia.org/wiki/ISO_week_date__;!!G
> qivPVa7Brio!LxlLxRzS6V8fuHzPVAnAczqQvPR708E_qdx6x3He2wfh95sRUnSwi7xVfdtCWDxz$
> 
> "An ISO week-numbering year (also called ISO year informally) has 52 or
> 53 full weeks. That is 364 or 371 days instead of the usual 365 or 366
> days. The extra week is sometimes referred to as a leap week, although
> ISO 8601 does not use this term. Weeks start with Monday. Each week's
> year is the Gregorian year in which the Thursday falls. The first week
> of the year, hence, always contains 4 January. ISO week year numbering
> therefore slightly deviates from the Gregorian for some days close to 1
> January."

Very cool.  Interesting.  Thanks for citing that, Lars.

bug#45608: 28.0.50; calendar-iso-date-string: "Day 6 of week 53 of 2020"

[Jean Louis]

Alright, thank you all for references.

ISO date was kind of interesting in communication with people I know
and I used it for quite a long time.

I will now start using normalized version like:

(calendar-date-string (calendar-current-date))
"Saturday, January 2, 2021"

Jean