Persian

NAME

Date::Calendar::Persian - Conversions from / to the Persian calendar

SYNOPSIS

Converting a Gregorian date (e.g. 16th February 2021) into Persian


use Date::Calendar::Persian;
my Date $dt-greg;
my Date::Calendar::Persian $dt-persian;

$dt-greg    .= new(2021, 2, 16);
$dt-persian .= new-from-date($dt-greg);

say $dt-persian;
# --> 1399-11-28
say $dt-persian.strftime("%A %d %B %Y");
# --> Se shanbe 28 Bahman 1399

Converting a Persian date (e.g. 1 Farvardin 1400) into Gregorian

use Date::Calendar::Persian;
my Date::Calendar::Persian $dt-persian;
my Date $dt-greg;

$dt-persian .= new(year => 1400, month => 1, day => 1);
$dt-greg   = $dt-persian.to-date;

say $dt-greg;
# --> 2021-03-21

Conversion with a calendar which defines days as sunset to sunset


use Date::Calendar::Strftime;
use Date::Calendar::Hebrew;
use Date::Calendar::Persian;
my  Date::Calendar::Persian $d-pe;
my  Date::Calendar::Hebrew  $d-he;

$d-pe .= new(year => 1403, month => 8, day => 23, daypart => before-sunrise());
$d-he .= new-from-date($d-pe);
say $d-he.strftime("%A %d %B %Y");
# ---> "Yom Reviʻi 12 Heshvan 5785"

$d-pe .= new(year => 1403, month => 8, day => 23, daypart => daylight());
$d-he .= new-from-date($d-pe);
say $d-he.strftime("%A %d %B %Y");
# ---> "Yom Reviʻi 12 Heshvan 5785" again

$d-pe .= new(year => 1403, month => 8, day => 23, daypart => after-sunset());
$d-he .= new-from-date($d-pe);
say $d-he.strftime("%A %d %B %Y");
# ---> "Yom Chamishi 13 Heshvan 5785" instead of "Yom Reviʻi 12 Heshvan 5785"

DESCRIPTION

Date::Calendar::Persian is a class representing dates in the Persian calendar. It allows you to convert a Persian date into Gregorian or into other implemented calendars, and it allows you to convert dates from Gregorian or from other calendars into Persian.

The Date::Calendar::Persian class gives the arithmetic version of the Persian calendar. The astronomic Persian calendar is partially implemented in Date::Calendar::Persian::Astronomical, included in this distribution.

METHODS

Constructors

new

Create an Persian date by giving the year, month and day numbers and optionally the day part.

new-from-date

Build an Persian 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 an Persian date from the Modified Julian Day number and from the daypart parameter (optional, defaults do daylight).

Accessors

gist

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

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.

day-abbr

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

daycount

The Modified Julian Day Number (a day-only scheme based on 17 November 1858).

day-of-week

The number of the day within the week (1 for Saturday / Shanbe, 7 for Friday / Jumee).

week-number

The number of the week within the year, 1 to 52 or 1 to 53. Similar to the "ISO date" as defined for Gregorian date. Week number 1 is the Sat→Fri span that contains the first Tuesday / Se shanbe of the year, week number 2 is the Sat→Fri span that contains the second Tuesday / Se shanbe of the year and so on.

week-year

Mostly similar to the year attribute. Yet, 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 Farvardin and ends on the 29th or 30th Esfand, the week-year always begins on Saturday / Shanbe and it always ends on Friday / Jumee.

day-of-year

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

Other Methods

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 "11 Bahman 1440" to the French Revolutionary calendar, you can code:


use Date::Calendar::Persian;
use Date::Calendar::FrenchRevolutionary;

my  Date::Calendar::Persian             $d-orig;
my  Date::Calendar::FrenchRevolutionary $d-dest-push;
my  Date::Calendar::FrenchRevolutionary $d-dest-pull;

$d-orig .= new(year  => 1440
             , month =>   11
             , day   =>   11);
$d-dest-push  = $d-orig.to-date("Date::Calendar::FrenchRevolutionary");
$d-dest-pull .= new-from-date($d-orig);

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. For the Gregorian calendar, instead of the core class Date, you can use the child class Date::Calendar::Gregorian which allows both push and pull styles.

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 11-char long, so the padding will always occur and will always include at least 14 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. Not used with the Persian calendar.
A mandatory type code.

The allowed type codes are:

%a

The abbreviated day of week.

%A

The full day of week name.

%b

The abbreviated month name.

%B

The full month name.

%d

The day of the month as a decimal number (range 01 to 31).

%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 12). 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 %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).

%m

The month as a two-digit decimal number (range 01 to 12), 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.

%%

A literal `%' character.

BUGS AND ISSUES

The astronomical Persian calendar is only partially implemented. It can represent dates only in the 1000 to 1800 years (1621 to 2421 in the Gregorian calendar).

Security issues

Another issue, as explained in the Date::Calendar::Strftime documentation. Please ensure that format-string passed to strftime comes from a trusted source. Failing that, you could get a format that includes a outrageous length in a strftime specifier, and you would 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::Persian: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

gist

year, month, day

daypart

month-name

month-abbr

day-name

day-abbr

daycount

day-of-week

week-number

week-year

day-of-year

Other Methods

to-date

strftime

BUGS AND ISSUES

Security issues

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

Time

SEE ALSO

Raku Software

Perl 5 Software

Other Software

Book

Internet

AUTHOR

COPYRIGHT AND LICENSE

Date::Calendar::Persian v0.1.0

Authors

License

Dependencies

Test Dependencies

Provides

Documentation