Date::Japanese::Era(3)

NAME
Date::Japanese::Era - Conversion between Japanese Era / Gregorian calendar

SYNOPSIS
  use Date::Japanese::Era;

  # from Gregorian (month + day required)
  $era = Date::Japanese::Era->new(1970, 1, 1);

  # from Japanese Era
  $era = Date::Japanese::Era->new('¾¼ÏÂ', 52);

  $name      = $era->name;         # '¾¼ÏÂ' in EUC-jp (default)
  $gengou    = $era->gengou;       # same

  $year      = $era->year;         # 52
  $gregorian = $era->gregorian_year;       # 1977

  # use JIS X0301 table for conversion
  use Date::Japanese::Era 'JIS_X0301';

DESCRIPTION
Date::Japanese::Era handles conversion between Japanese Era and Gregorian calendar.

METHODS

codeset
      $codeset = Date::Japanese::Era->codeset;
      Date::Japanese::Era->codeset($encoding);

    sets / gets external encoding of Japanese era names. For example with the following code, input and output of era names are encoded in UTF-8.

      Date::Japanese::Era->codeset('utf8');
      $era = Date::Japanese::Era->new($name, $year); # $name is UTF-8
      print $era->name;                              # also UTF-8

    You need Jcode module installed to make use of this feature. Otherwise, calls to codeset() are simply ignored (with warning).

new
      $era = Date::Japanese::Era->new($year, $month, $day);
      $era = Date::Japanese::Era->new($era_name, $year);

    Constructs new Date::Japanese::Era instance. When constructed from Gregorian date, month and day is required. You need Date::Calc to construct from Gregorian.

    Name of era can be either of Japanese / ASCII. Input encodings can be specified via codeset(), suppose you have Jcode module installed. Default is EUC-JP.

    Exceptions are thrown when inputs are invalid (e.g: non-existent era name and year combination, unknwon era-name, etc.).

name
      $name = $era->name;

    returns era name in Japanese. Encoding can be specified via codeset() class method. Default is EUC-JP.

gengou
    alias for name().

name_ascii
      $name_ascii = $era->name_ascii;

    returns era name in US-ASCII.

year
      $year = $era->year;

    returns year as Japanese era.

gregorian_year
      $year = $era->gregorian_year;

    returns year as Gregorian.

EXAMPLES
  use Date::Japanese::Era;

  # 2001 is H-13
  my $era = Date::Japanese::Era->new(2001, 8, 31);
  printf "%s-%s", uc(substr($era->name_ascii, 0, 1)), $era->year;

  # to Gregorian
  my $era = Date::Japanese::Era->new('Ê¿À®', 13);
  print $era->gregorian_year;   # 2001

CAVEATS

•   Currently supported era is up to 'meiji'. And before Meiji 05.12.02, gregorius calendar was not used there, but lunar calendar was. This module does not support lunar calendar, but gives warnings in such cases ("In %d they didn't use gregorius calendar").

•   There should be discussion how we handle the exact day the era has changed (former one or latter one?). This module default handles the day as newer one, but you can change so that it sticks to JIS table (older one) by saying:

      use Date::Japanese::Era 'JIS_X0301';

    For example, 1912-07-30 is handled as:

      default       Taishou 1 07-30
      JIS_X0301     Meiji 45 07-30

•   If someday current era (heisei) is changed, Date::Japanese::Era::Table should be upgraded.

TODO

•   Date parameters can be in various format. I should replace Date::Simple or whatever for that.

•   Support earlier eras and lunar calendar.

AUTHOR
Tatsuhiko Miyagawa <miyagawa@bulknews.net>

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO
Date::Calc, Jcode, Date::Simple