CopticEthiopic

NAME

Date::Calendar::CopticEthiopic - conversions from / to the Coptic calendar and from / to the Ethiopic calendar

SYNOPSIS

Converting a Gregorian date to both Coptic and Ethiopic


use Date::Calendar::Coptic;
use Date::Calendar::Ethiopic;

my Date                     $Perlcon-Riga-grg;
my Date::Calendar::Coptic   $Perlcon-Riga-cop;
my Date::Calendar::Ethiopic $Perlcon-Riga-eth;

$Perlcon-Riga-grg .= new(2019, 8, 7);
$Perlcon-Riga-cop .= new-from-date($Perlcon-Riga-grg);
$Perlcon-Riga-eth .= new-from-date($Perlcon-Riga-grg);

say $Perlcon-Riga-cop.strftime("%A %e %B %Y");
#--> Peftoou 1 Mesori 1735
say $Perlcon-Riga-eth.strftime("%A %e %B %Y");
#--> Rob 1 Nähase 2011

Converting a Coptic date and an Ethiopic date to Gregorian


use Date::Calendar::Coptic;
use Date::Calendar::Ethiopic;

my Date::Calendar::Coptic   $TPC-Pittsburgh-cop;
my Date::Calendar::Ethiopic $TPC-Pittsburgh-eth;
my Date                     $TPC-Pittsburgh-grg1;
my Date                     $TPC-Pittsburgh-grg2;

$TPC-Pittsburgh-cop .= new(year => 1735, month => 10, day => 9);
$TPC-Pittsburgh-grg1 = $TPC-Pittsburgh-cop.to-date;
say $TPC-Pittsburgh-cop.strftime("%e %B %Y = "), $TPC-Pittsburgh-grg1.gist;
#--> 9 Paoni 1735 = 2019-06-16

$TPC-Pittsburgh-eth .= new(year => 2011, month => 10, day => 14);
$TPC-Pittsburgh-grg2 = $TPC-Pittsburgh-eth.to-date;
say $TPC-Pittsburgh-eth.strftime("%e %B %Y = "), $TPC-Pittsburgh-grg2.gist;
#--> 14 Säne 2011 = 2019-06-21

Converting a date from Gregorian to Coptic and Ethiopic, while paying attention to the sunset:


use Date::Calendar::Strftime;
use Date::Calendar::Gregorian;
use Date::Calendar::Coptic;
use Date::Calendar::Ethiopic;

my Date::Calendar::Gregorian $d-grg;
my Date::Calendar::Coptic    $d-cop;
my Date::Calendar::Ethiopic  $d-eth;

$d-grg .= new('2024-11-13', daypart => before-sunrise());
$d-cop .= new-from-date($d-grg);
$d-eth .= new-from-date($d-grg);
say $d-cop.strftime("%A %e %B %Y"), $d-eth.strftime(" %A %e %B %Y");
# -->  Peftoou  4 Hathor 1741 Rob  4 Ḫədar 2017

$d-grg .= new('2024-11-13', daypart => daylight());
$d-cop .= new-from-date($d-grg);
$d-eth .= new-from-date($d-grg);
say $d-cop.strftime("%A %e %B %Y"), $d-eth.strftime(" %A %e %B %Y");
# -->  Peftoou  4 Hathor 1741 Rob  4 Ḫədar 2017 (again)

$d-grg .= new('2024-11-13', daypart => after-sunset());
$d-cop .= new-from-date($d-grg);
$d-eth .= new-from-date($d-grg);
say $d-cop.strftime("%A %e %B %Y"), $d-eth.strftime(" %A %e %B %Y");
# -->  Ptiou  5 Hathor 1741 Hamus  5 Ḫədar 2017

DESCRIPTION

Date::Calendar::CopticEthiopic is a module distribution providing two classes, Date::Calendar::Coptic and Date::Calendar::Ethiopic. The corresponding calendars both derive from the ancient Egyptian calendar. In each, a year consists of 12 months with 30 days each, plus 5 or 6 additional days (epagomene) at the end of the year. Leap years occurs every fourth year, with no adjustment for century years. The calendars also define weeks which last for 7 days, beginning on sunday and ending on saturday.

METHODS

Constructors

new

Create a Coptic or Ethiopic date by giving the year, month and day numbers, plus optionally the day part (before-sunrise, daylight or after-sunset).

new-from-date

Build a Coptic or Ethiopic date by cloning an object from another class. This other class can be the core class Date or any Date::Calendar::xxx class with a daycount method and, hopefully, a daypart method.

new-from-daycount

Build a Coptic or Ethiopic date from the Modified Julian Day number and the daypart value.

Accessors

year, month, day

The numbers defining the date.

daypart

A number indicating which part of the day. This number should be filled and compared with the following subroutines, with self-documenting names:

before-sunrise()
daylight()
after-sunset()

month-name

The month of the date, as a string.

month-abbr

The month of the date, as a 3-char string.

day-name

The name of the day within the week, as a string.

day-abbr

The name of the day within the week, as a 3-char string.

day-of-week

The number of the day within the week (1 for sunday / Tkyriakē / Ihud, 7 for saturday / Psabbaton / Kidamme).

week-number

The number of the week within the year, 1 to 52 (or even 53 on some years). Similar to the "ISO date" as defined for Gregorian date. Week number 1 is the Sun→Sat span that contains the first Wednesday / Peftoou / Rob of the year. This first week may start as soon as the 3rd epagomene day (or 4th on leap year) or as late as 4 Thout / Mäskäräm. Likewise, the last week of the year may end as soon as the 2nd epagomene day or it may last until 3rd Thout of the following year.

week-year

Mostly similar to the year attribute. Yet, as described for the so-called "ISO-date" for the Gregorian calendar and as explained above, the last days of the year and the first days of the following year can be sort-of transferred to the other year. The week-year attribute reflects this transfer. While the real year always begins on 1st Thout / Mäskäräm and ends on the 5th (6th if leap) epagomene day, the week-year always begins on Sunday / Tkyriakē / Ihud and it always ends 364 or 371 days later on Saturday / Psabbaton / Kidamme.

day-of-year

How many days since the beginning of the year. 1 to 365 on normal years, 1 to 366 on leap years.

daycount

The MJD value (Modified Julian Date) for the date.

Other Methods

gist

Gives a short string representing the date, in YYYY-MM-DD format.

to-date

Clones the date into a core class Date object or some Date::Calendar::xxx compatible calendar class. The target class name is given as a positional parameter. This parameter is optional, the default value is "Date" for the Gregorian calendar.

To convert a date from a calendar to another, you have two conversion styles, a "push" conversion and a "pull" conversion. For example, while converting from the Coptic date "10 Thout 1736" to Ethiopic, you can code:


use Date::Calendar::Coptic;
use Date::Calendar::Ethiopic;

my  Date::Calendar::Coptic   $d-orig;
my  Date::Calendar::Ethiopic $d-dest-push;
my  Date::Calendar::Ethiopic $d-dest-pull;

$d-orig .= new(year  => 1736
             , month =>    1
             , day   =>   10);
$d-dest-push  = $d-orig.to-date("Date::Calendar::Ethiopic");
$d-dest-pull .= new-from-date($d-orig);
say $d-orig, ' ', $d-dest-push, ' ', $d-dest-pull;
# --> 1736-01-10 2012-01-10 2012-01-10

And $d-dest-push and $d-dest-pull result in the same date.

When converting from the core class Date, use the pull style. When converting to the core class Date, use the push style. When converting from any class other than the core class Date to any other class other than the core class Date, use the style you prefer.

Please note that the class Date::Calendar::Gregorian can be used instead of the core class Date to implement Gregorian dates. And with this class, you can use both the push and the pull methods, just like the other Date::Calendar::xxx classes.

strftime

This method is very similar to the homonymous functions you can find in several languages (C, shell, etc). It also takes some ideas from printf-similar functions. For example


$df.strftime("%04d blah blah blah %-25B")

will give the day number padded on the left with 2 or 3 zeroes to produce a 4-digit substring, plus the substring " blah blah blah ", plus the month name, padded on the right with enough spaces to produce a 25-char substring. Thus, the whole string will be at least 42 chars long. By the way, you can drop the "at least" mention, because the longest month name is 15-char long, so the padding will always occur and will always include at least 10 spaces.

A strftime specifier consists of:

A percent sign,
An optional minus sign, to indicate on which side the padding occurs. If the minus sign is present, the value is aligned to the left and the padding spaces are added to the right. If it is not there, the value is aligned to the right and the padding chars (spaces or zeroes) are added to the left.
An optional zero digit, to choose the padding char for right-aligned values. If the zero char is present, padding is done with zeroes. Else, it is done wih spaces.
An optional length, which specifies the minimum length of the result substring.
An optional "E" or "O" modifier. On some older UNIX system, these were used to give the extended or localized version of the date attribute. Here, they rather give alternate variants of the date attribute.
A mandatory type code.

The allowed type codes are:

%a

The abbreviated day of week name.

%A

The full day of week name.

%b

The abbreviated month name.

%B

The full month name.

%c

The date-time, using the default format, as defined by the current locale.

%d

The day of the month as a decimal number (range 01 to 30).

%e

Like %d, the day of the month as a decimal number, but a leading zero is replaced by a space.

%f

The month as a decimal number (1 to 13). Unlike %m, a leading zero is replaced by a space.

%F

Equivalent to %Y-%m-%d (the ISO 8601 date format)

%G

The "week year" as a decimal number. Mostly similar to %L and %Y, but it may differ on the very first days of the year or on the very last days. Analogous to the year number in the so-called "ISO date" format for Gregorian dates.

%j

The day of the year as a decimal number (range 001 to 366).

%L

The year as a decimal number. Strictly similar to %Y and mostly similar to %G.

Since 2024 and the release of Date::Calendar::Strfrtime version 0.0.4, this strftime specifier is deprecated.

%m

The month as a two-digit decimal number (range 01 to 13), including a leading zero if necessary.

%n

A newline character.

%Ep

Gives a 1-char string representing the day part:

☾ or U+263E before sunrise,
☼ or U+263C during daylight,
☽ or U+263D after sunset.

Rationale: in C or in other programming languages, when strftime deals with a date-time object, the day is split into two parts, before noon and after noon. The %p specifier reflects this by giving a "AM" or "PM" string.

The 3-part splitting in the Date::Calendar::xxx may be considered as an alternate splitting of a day. To reflect this in strftime, we use an alternate version of %p, therefore %Ep.

%t

A tab character.

%u

The day of week as a 1..7 number.

%V

The week number as defined above, similar to the week number in the so-called "ISO date" format for Gregorian dates.

%Y

The year as a decimal number. Strictly similar to %L and mostly similar to %G.

%%

A literal `%' character.

ISSUES, BUGS, ETC

I am no expert in the Sahidic (Coptic) language and in the Amharic (Ethiopic) language. I have copied / pasted names from free sources, but I am in no position to recognize which sources are authoritative or not. Also, I have kept the Latin script (although with some diacritics) and not the Coptic script.

Ethiopic or Ethiopian? Some English-speaking sources (see below) use Ethiopic, the others use Ethiopian. Since the first source I have read is Reingold's and Dershowitz' book, I have used the same term as them, Ethiopic.

Security issues

As explained in the Date::Calendar::Strftime documentation, please ensure that format-string passed to strftime comes from a trusted source. Failing that, the untrusted source can include a outrageous length in a strftime specifier and this will drain your PC's RAM very fast.

Relations with :ver<0.0.x> classes and with core class Date

Version 0.1.0 (and API 1) was introduced to ease the conversions with other calendars in which the day is defined as sunset-to-sunset. If all Date::Calendar::xxx classes use version 0.1.x and API 1, the conversions will be correct. But if some Date::Calendar::xxx classes use version 0.0.x and API 0, there might be problems.

A date from a 0.0.x class has no daypart attribute. But when "seen" from a 0.1.x class, the 0.0.x date seems to have a daypart attribute equal to daylight. When converted from a 0.1.x class to a 0.0.x class, the date may just shift from after-sunset (or before-sunrise) to daylight, or it may shift to the daylight part of the prior (or next) date. This means that a roundtrip with cascade conversions may give the starting date, or it may give the date prior or after the starting date.

If you install <Date::Calendar::CopticEthiopic:ver<0.1.0>>, why would you refrain from upgrading other Date::Calendar::xxxx classes? So actually, this issue applies mainly to the core class Date, because you may prefer avoiding the installation of Date::Calendar::Gregorian.

Time

This module and the Date::Calendar::xxx associated modules are still date modules, they are not date-time modules. The user has to give the daypart attribute as a value among before-sunrise, daylight or after-sunset. There is no provision to give a HHMMSS time and convert it to a daypart parameter.

AUTHOR

Jean Forget <J2N-FORGET at orange dot fr>

COPYRIGHT AND LICENSE

This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.

NAME

SYNOPSIS

DESCRIPTION

METHODS

Constructors

new

new-from-date

new-from-daycount

Accessors

year, month, day

daypart

month-name

month-abbr

day-name

day-abbr

day-of-week

week-number

week-year

day-of-year

daycount

Other Methods

gist

to-date

strftime

ISSUES, BUGS, ETC

Security issues

Relations with :ver<0.0.x> classes and with core class Date

Time

SEE ALSO

Internet

Raku Software

Perl 5 Software

Other Software

Books

AUTHOR

COPYRIGHT AND LICENSE

Date::Calendar::CopticEthiopic v0.1.1

Authors

License

Dependencies

Test Dependencies

Provides

Documentation