[<<]Message[>>]    [<<]Author[>>]    [<<]Subject[>>]    [<<]Thread[>>]

Number   :  4440
Date     :  2003-04-24
Author   :  Kan Yabumoto
Subject  :  Re: Date Macro
Size(KB) :  4



Garry wrote:

>You could even go the whole hog and include ISO Week No ($WW$ or
>$WK$?) so someone could create the alternate date format in the form
>2003-W14-2 (yyyy-Wweekno-dayofweek). Although the following is a bit
>clumsy it is feasible.
>
>/$yyyy$-W/$ww-w$

That's interesting. I could do that. I would use /$KK$
rather than /$WW$ (see below for why). Also, for the
convenience of adding the prefix, W to easily conform to the
ISO 8601 standard, we can define /$WKK$ specifically for that.
So, /$KK$ will expand to a value like 17 and /$WKK$ expands
to W17.

Therefore, Garry's "clumsy" notation will be cleaned up;

/$yyyy-wkk-k$ (See below for the single /$K$)

I was not aware that the ISO standard assigns the radix
value of 7 for Sunday. That seems contrary to my sense
of tradition that most people consider Sunday as the
beginning of the week. Look at Window's Date and Time
display. The calendar clearly shows Sunday to the left
which is the most common calendar I've seen.
Apparently, ISO treats a week as starting on Monday and
ending on Sunday.

The ISO web page does not tell it explicitly.

http://www.iso.ch/iso/en/prods-services/popstds/datesandtime.html

But, from its context, it is reasonable to interpret that
ISO defines that a week starts on Monday.

It is easy for me to convert the Sunday value for /$W$
to 7 rather than 0. But that would break existing user's
batch file. Besides, it will not allow concatenation of
W17 notation with the single digit radix value of
the day of the week. So, We could assign a new mnemonic
to the ISO-way of the day-of-the-week radix value using /$K$

--------------------------------------------------------
The current /$W$ scheme (Sun:0 - Sat:6) was not rally
an arbitrary choice. It has been done and can be
considered an established convention if not a standard.
--------------------------------------------------------

So, if you say /$yyyy-wkk-k$, it will be expanded to

2003-W17-4 // 4th day of Week 17 of 2003 == 2003-04-24

And, you can say /$yyyywkkk$ which expands to 2003W174
(Since the /$KK$ notation always uses a 2-digit value
(with a leading zero when needed) and the /$K$ value
is always a single digit, no ambiguity there.

Here, some careful reader may notice that we have been
keeping the macro keywords to exactly match the length of
the expanded string. All of the newly proposed macro
keywords here remain true to this rule.

Alas, the variable-length /$m$, /$d$, /$h$, /$n$ and /$s$
that started all this discussion broke this rule which
was another reason for my grumble for that.

Well, some stubborn people may insist on a version
without the leading zero for the /$KK value --- they
should be sent to the Guantanamo Bay camp and learn
the Koran first.

-----------------------------------------------------------
You may ask "why not /$WW$ instead of /$KK$ ?".
We chose /$WWW$ for day-of-the-week and /$W$ also
for day-of-the-week in radix -- they are both
representing the same thing in different formats.
But, the week-of-the-year is a different concept
and using /$WW$ would somehow break the symmetry.
Besides, this notation would be most convenient
when the week-of-the-year and numeric day-of-the-week
are specified side-by-side without break. Considering
the precedence rule (the longest keyword matches
first), assigning /$KK$ seems more convenient than /$WW$.
It is unfortunate that we had /$W$ that turned out to
be non-ISO (and /$KK$ and /$K$ are not symmetrical).
-----------------------------------------------------------

One benefit of treating Monday as the first day of the
week is that Saturday and Sunday can be more easily
treated as a contiguous entity --- I guess this has
more benefit to nearly everyone even though most
calendars we encounter will likely to continue with
Sunday at the left most column.

Well, figuring the week-of-the-year value will be
a bit of a pain to program. But, it should not be
too bad (XXCOPY already knows how to convert a date
to the day-of-the-week and also knows the leap-year
rules).

Kan Yabumoto



This message if part of XXCOPY's message Archive.
The archive contains all the messages posted at Yahoo!Groups: XXCOPY.