[REBOL] Re: [date date! month month-bounds] MONTH-BOUNDS func design
From: carl:cybercraft at: 29-Jan-2008 7:23
On Monday, 28-January-2008 at 16:08:40 Gregg Irwin wrote,
>Another example question, which I almost posted as the primer question
>on this topic, is whether a LEAP-YEAR? func should always require a
>year, or should it default to the current year, and use a refinement
>if you want a different year.
I'd go for always...
if leap-year? now [...]
if leap-year? 1986 [...]
if leap-year? 28-Jan-2008 [...]
The alternatives being just confusing...
if leap-year? [...]
if leap-year?/year 1986 [...]
if leap-year?/year 28-Jan-2008 [...]
Thew first is ambigious, as it could be read (by human readers of the script) as querying
if the block contains a leap-year, with the others being longer than they need to be.
While...
if leap-year?/now [...]
if leap-year? 1986 [...]
if leap-year? 28-Jan-2008 [...]
is hardly better than the always approach.
>And the same question for MONTH-BOUNDS applies to WEEK-BOUNDS.
>
>EOC> Reaching back to my smalltalk days, I recall that they had a lot of
>EOC> nice classes that helped with calendars. The methods DaysInMonth and
>EOC> CalendarForMonth come to mind, iirc.
>
>I have DaysInMonth already, and a lot of others, e.g.
>same-day-last-month, year-week, weeks-in-year, week-bounds. And a copy
>of Ed's calc-workdays funcs. :)
>
>CR> Why are two values even required? Is there any month that doesn't
>CR> start on the 1st? It's useful to be able to get the last day of a
>CR> month since they vary, but I don't see the need for returning
>CR> a block with the first as well in it.
>
>EOC> Don't we always know what the date of a given month is? And the
>EOC> start time/end times for any month? :^)
>
>Starting today, what do you have to do to get a list of all dates in
>the current month?
That's why days-in-month is needed. It doesn't explain why you need the month-bounds
block. If I had days-in-month, I'd do it something like this...
today: now
repeat day days-in-month today [today/day: day print today/date]
How would month-bounds inprove on that?
>Or how do you compare a date to see if it was last
>month,
Currently, like so...
date: now date/month: date/month - 1
if all [foo/year = date/year foo/month = date/month][...]
I'm open to the idea that month-bounds would improve on that. How would it be used to
do it?
>or in any given date range?
How would month-bounds help you with that?
I'd use...
if all [date >= low-date date <= high-date][...]
>That is, how can we best express the abstraction of date and time
>ranges? For a monthly calendar display, you need just the dates. For a
>scheduler that gives you daily and weekly views, you need more detail.
>
>In the case of month-bounds, let's say a user can say "find me all the
>files that were added/updated between x and y". Given dates, or just a
>month name (files updated in jan-2008), we need the time detail to
>catch everything.
But only for the end of the month, since...
>> 1-jan-2008 = 1-jan-2008/0:0:0
== true
(Only thinking of month-bounds or week-bounds there.)
