Re: r30398 - docs/Perl6/Spec/S32-setting-library
Am 20.04.2010 16:59, schrieb Dave Rolsky: On Fri, 16 Apr 2010, pugs-comm...@feather.perl6.nl wrote: +=head2 Semi-internal methods + +[This section is severely conjectural] + +For efficient implementation of arithmetics on CDate objects, two more +methods are exposed: + + $d.daycount + Date.new-from-daycount(Int $daycount) I'd _really_ like to see this be based on Rata Die, which is January 1, 0001. See http://en.wikipedia.org/wiki/Rata_Die Your answer made it clear to me that people are not going to like the daycount (or day-count) accessor. I consciously did not specify an epoch on which daycount was based because I didn't want to force the implemntor's hand more than absolutely necessary. Since number-of-days-relative-to-a-fixed-epoch is still available trivially as $date - $start-of-epoch I've now removed the daycount related methods. Cheers, Moritz
Re: r30398 - docs/Perl6/Spec/S32-setting-library
On Fri, 16 Apr 2010, pugs-comm...@feather.perl6.nl wrote: +=head2 Semi-internal methods + +[This section is severely conjectural] + +For efficient implementation of arithmetics on CDate objects, two more +methods are exposed: + +$d.daycount +Date.new-from-daycount(Int $daycount) I'd _really_ like to see this be based on Rata Die, which is January 1, 0001. See http://en.wikipedia.org/wiki/Rata_Die This epoch value is used as the basis for many calendrical calculations in the Calendarical Calculations book, and has in turn been used as the method for calendar conversion in the Perl 5 DateTime sweet. Exposing this value explicitly (rata-die-day-count) would be a wise decision, IMO. Also, day-count, not daycount ;) -dave /* http://VegGuide.org http://blog.urth.org Your guide to all that's veg House Absolute(ly Pointless) */
Re: r30398 - docs/Perl6/Spec/S32-setting-library
On Tue, Apr 20, 2010 at 10:59 AM, Dave Rolsky auta...@urth.org wrote: I'd _really_ like to see this be based on Rata Die, which is January 1, 0001. See http://en.wikipedia.org/wiki/Rata_Die To be clear, that's specifically January 1, 1 CE in the retrojected Gregorian calendar, which is the same day as January 1, 3 CE in the retrojected Julian calendar; noon UTC began Julian Day 1,721,426. You could also use the JD directly, but there's a subtle design decision lurking there. The JD is tied to UTC, and refers to a specific 24-hour period that is the same across the planet: JD 2,455,307 began 4 hours and 45 minutes ago as I write this, and will be over in 19 hours and 15 minutes, and that is a universal fact no matter whether it's currently Tuesday the 20th or already Wednesday the 21st where you are. An RD, in contrast, is not tied to a specific time zone, but is simply a numerical way to represent exactly the same concept as the date: whatever the Gregorian date April 20, 2010 means, RD 733,882 means the same thing. So on some parts of the planet its RD 733,882 and in others it's already RD 733,883. The RD is thus a better fit for the Date class, which is a representation of an abstract date, unanchored in spacetime. An integral JD number may be used to fit the same bill, but opens the possibility of confusion with the more typical anchored JD values (which might even be available from DateTime objects). The difference between them, or with any other epoch choice, is mostly just a matter of a constant which can be added or subtracted as needed, and to the degree that's true this is just bikeshed painting. But the part that isn't is important: I don't want to dilute what I see as the primary benefit of a Date object over a DateTime object that simply has its time fields zeroed, which is flexibility. The latter is still by implication tied to a specific swath of spacetime (e.g. midnight to midnight in some time zone), whereas the former is free to refer to whatever the human date designation can. -- Mark J. Reed markjr...@gmail.com
r30398 - docs/Perl6/Spec/S32-setting-library
Author: moritz
Date: 2010-04-16 22:40:37 +0200 (Fri, 16 Apr 2010)
New Revision: 30398
Modified:
docs/Perl6/Spec/S32-setting-library/Temporal.pod
Log:
[S32/Temporal] spec Date type
This is heavily inspired by Date::Simple on CPAN, and mostly implemented
at http://github.com/moritz/Date/ as an external module, that currently works
fine with Rakudo (but is really compiler agnostic).
Modified: docs/Perl6/Spec/S32-setting-library/Temporal.pod
===
--- docs/Perl6/Spec/S32-setting-library/Temporal.pod2010-04-16 15:47:23 UTC
(rev 30397)
+++ docs/Perl6/Spec/S32-setting-library/Temporal.pod2010-04-16 20:40:37 UTC
(rev 30398)
@@ -8,6 +8,7 @@
Carl Mäsak cma...@gmail.com
Martin Berends mbere...@autoexec.demon.nl
+Moritz Lenz mor...@faui2k3.org
(and others named in FOOTNOTE at bottom)
=head1 VERSION
@@ -74,6 +75,11 @@
This has the same effect as doing CDateTime.now().truncate('day'); see
'Set methods' below.
+Or if you want to extract the date as a CDate object (see below),
+you can use simple type coercion:
+
+my $today = $datetime.Date;
+
General dates can be specified through the Cnew constructor:
my $moonlanding = DateTime.new( :year(1969), :month(7), :day(16),
@@ -195,6 +201,62 @@
Monday of the week in which it occurs, and the time components are all
set to 0.
+=head1 Date
+
+CDate objects represent a day without a time component, and allow easier
+manipulation by assuming that integers always mean days.
+
+Days, Months and days of week are 1-based.
+
+=head2 Constructors
+
+Date.today(); # today's date
+Date.new('2010-12-24'); # -MM-DD format
+Date.new(:year(2010), :month(12), :day(24));
+Date.new(2010, 12, 24);
+
+The constructors die with a helpful error message if month or day are out of
+range.
+
+=head2 Accessors
+
+The following accessors are pretty obvious, and are defined by example only.
+See the test suite for more formal definitions.
+
+my $d = Date.new('2010-12-24');
+$d.year # 2010
+$d.month# 12
+$d.day # 24
+$d.day-of-week # 5 # Friday
+$d.is-leap-year # Bool::False
+$d.days-in-month# 31
+$d.Str # '2010-12-24'
+
+=head2 Arithmetics
+
+$d.succ # Date.new('2010-12-25')
+$d.pred # Date.new('2010-12-23')
+$d - Date.new('1984-03-02') # 9793 # (difference in days)
+$d - 42 # Date.new('2010-11-12')
+$d + 3 # Date.new('2010-12-27')
+3 + $d # Date.new('2010-12-27')
+
+=head2 Semi-internal methods
+
+[This section is severely conjectural]
+
+For efficient implementation of arithmetics on CDate objects, two more
+methods are exposed:
+
+$d.daycount
+Date.new-from-daycount(Int $daycount)
+
+The Cdaycount method returns the difference of number of days between the
+current object and an arbitrary start of epoch. This epoch is arbitrary and
+implementation dependent, and is even allowed to change between invocations of
+the same program. The Cnew-from-daycount constructor creates a new CDate
+object with a given daycount.
+
=head1 Additions
Please post errors and feedback to Cperl6-language. If you are making
r30398 - docs/Perl6/Spec/S32-setting-library
I would only add that I think the DateTime constructor should accept a
Date object:
my $bday = new Date.new(1968, 5, 5);
my $specifically = DateTime.new(:date($bday), :hour(20), :minute(47));
or at least, Date should have a method that returns it's value as
pairs suitable for passing to DateTime.new.
On Friday, April 16, 2010, pugs-comm...@feather.perl6.nl wrote:
Author: moritz
Date: 2010-04-16 22:40:37 +0200 (Fri, 16 Apr 2010)
New Revision: 30398
Modified:
docs/Perl6/Spec/S32-setting-library/Temporal.pod
Log:
[S32/Temporal] spec Date type
This is heavily inspired by Date::Simple on CPAN, and mostly implemented
at http://github.com/moritz/Date/ as an external module, that currently works
fine with Rakudo (but is really compiler agnostic).
Modified: docs/Perl6/Spec/S32-setting-library/Temporal.pod
===
--- docs/Perl6/Spec/S32-setting-library/Temporal.pod 2010-04-16 15:47:23
UTC (rev 30397)
+++ docs/Perl6/Spec/S32-setting-library/Temporal.pod 2010-04-16 20:40:37
UTC (rev 30398)
@@ -8,6 +8,7 @@
Carl Mäsak cma...@gmail.com
Martin Berends mbere...@autoexec.demon.nl
+ Moritz Lenz mor...@faui2k3.org
(and others named in FOOTNOTE at bottom)
=head1 VERSION
@@ -74,6 +75,11 @@
This has the same effect as doing CDateTime.now().truncate('day'); see
'Set methods' below.
+Or if you want to extract the date as a CDate object (see below),
+you can use simple type coercion:
+
+ my $today = $datetime.Date;
+
General dates can be specified through the Cnew constructor:
my $moonlanding = DateTime.new( :year(1969), :month(7), :day(16),
@@ -195,6 +201,62 @@
Monday of the week in which it occurs, and the time components are all
set to 0.
+=head1 Date
+
+CDate objects represent a day without a time component, and allow easier
+manipulation by assuming that integers always mean days.
+
+Days, Months and days of week are 1-based.
+
+=head2 Constructors
+
+ Date.today(); # today's date
+ Date.new('2010-12-24'); # -MM-DD format
+ Date.new(:year(2010), :month(12), :day(24));
+ Date.new(2010, 12, 24);
+
+The constructors die with a helpful error message if month or day are out of
+range.
+
+=head2 Accessors
+
+The following accessors are pretty obvious, and are defined by example only.
+See the test suite for more formal definitions.
+
+ my $d = Date.new('2010-12-24');
+ $d.year # 2010
+ $d.month # 12
+ $d.day # 24
+ $d.day-of-week # 5 # Friday
+ $d.is-leap-year # Bool::False
+ $d.days-in-month # 31
+ $d.Str # '2010-12-24'
+
+=head2 Arithmetics
+
+ $d.succ # Date.new('2010-12-25')
+ $d.pred # Date.new('2010-12-23')
+ $d - Date.new('1984-03-02') # 9793 # (difference in days)
+ $d - 42 # Date.new('2010-11-12')
+ $d + 3 # Date.new('2010-12-27')
+ 3 + $d # Date.new('2010-12-27')
+
+=head2 Semi-internal methods
+
+[This section is severely conjectural]
+
+For efficient implementation of arithmetics on CDate objects, two more
+methods are exposed:
+
+ $d.daycount
+ Date.new-from-daycount(Int $daycount)
+
+The Cdaycount method returns the difference of number of days between the
+current object and an arbitrary start of epoch. This epoch is arbitrary and
+implementation dependent, and is even allowed to change between invocations
of
+the same program. The Cnew-from-daycount constructor creates a new CDate
+object with a given daycount.
+
=head1 Additions
Please post errors and feedback to Cperl6-language. If you are making
--
Mark J. Reed markjr...@gmail.com
Re: r30398 - docs/Perl6/Spec/S32-setting-library
On Friday, April 16, 2010, Mark J. Reed markjr...@gmail.com wrote: or at least, Date should have a method that returns it's value as pairs suitable for passing to DateTime.new. Obviously that should be its value. Thank you, iPhone, for thinking you know better than I how to punctuate. :) -- Mark J. Reed markjr...@gmail.com
