DateTime::Calendar::Pataphysical - Dates in the pataphysical calendar


  use DateTime::Calendar::Pataphysical;

  $dt = DateTime::Calendar::Pataphysical->new( year  => 1752,
                                               month => 10,
                                               day   => 4 );


DateTime::Calendar::Pataphysical is the implementation of the pataphysical calendar. Each year in this calendar contains 13 months of 29 days. This regularity makes this a convenient alternative for the irregular Gregorian calendar.

This module is designed to be easy to use in combination with DateTime. Most of its methods correspond to a DateTime method of the same name.


  • new( ... )

    This class method accepts parameters for each date and time component: "year", "month", "day". Additionally, it accepts a "locale" parameter.

    The "rd_secs" parameter is also accepted. This parameter is only useful in conversions to other calendars; this calendar does not use its value.

  • from_epoch( epoch => $epoch, ... )

    This class method can be used to construct a new object from an epoch time instead of components. Just as with the new() method, it accepts a "locale" parameter.

  • now( ... )

    This class method is equivalent to calling from_epoch() with the value returned from Perl's time() function.

  • from_object( object => $object, ... )

    This class method can be used to construct a new object from any object that implements the utc_rd_values() method. All DateTime::Calendar modules must implement this method in order to provide cross-calendar compatibility. This method accepts a "locale" parameter.

    The time part of $object is stored, and will only be used if the created object is converted to another calendar. Only the date part of $object is used to calculate the Pataphysical date. This calculation is based on the local time and date of $object.

  • last_day_of_month( ... )

    This constructor takes the same arguments as can be given to the now() method, except for "day". Additionally, both "year" and "month" are required.

  • clone

    This object method returns a replica of the given object.

  • year

    Returns the year.

  • month

    Returns the month of the year, from 1..13.

  • month_name

    Returns the name of the current month.

  • day_of_month, day, mday

    Returns the day of the month, from 1..29.

  • day_of_week, wday, dow

    Returns the day of the week as a number, from 1..7, with 1 being Sunday and 7 being Saturday.

  • day_name

    Returns the name of the current day of the week.

  • day_of_year, doy

    Returns the day of the year.

  • ymd( $optional_separator ), date

  • mdy( $optional_separator )

  • dmy( $optional_separator )

    Each method returns the year, month, and day, in the order indicated by the method name. Years are zero-padded to four digits. Months and days are 0-padded to two digits.

    By default, the values are separated by a dash (-), but this can be overridden by passing a value to the method.

  • datetime

    Equivalent to

      $dt->ymd('-') . 'EP'
  • is_leap_year

    This method returns a true or false indicating whether or not the datetime object is in a leap year.

  • week

     ($week_year, $week_number) = $dt->week

    Returns information about the calendar week which contains this datetime object. The values returned by this method are also available separately through the week_year and week_number methods.

  • week_year

    Returns the year of the week. In the pataphysical calendar, this is equal to the year of the date, as all weeks fall in one year only.

  • week_number

    Returns the week of the year, from 1..53.

    The 29th of each month falls outside of any week; week_number returns undef for these dates.

  • utc_rd_values

    Returns the current UTC Rata Die days and seconds as a two element list. This exists primarily to allow other calendar modules to create objects based on the values provided by this object.

  • utc_rd_as_seconds

    Returns the current UTC Rata Die days and seconds purely as seconds. This is useful when you need a single number to represent a date.

  • strftime( $format, ... )

    This method implements functionality similar to the strftime() method in C. However, if given multiple format strings, then it will return multiple elements, one for each format string.

    See DateTime for a list of all possible format specifiers. This module implements all specifiers related to dates. There is one additional specifier: %* represents the feast of that date.

  • feast

    Returns the feast or vacuation of the given date.

  • type_of_feast

    Returns the type of feast or vacuation.

      '*' means Fête Suprème Première première
      '1' means Fête Suprème Première seconde
      '2' means Fête Suprème Seconde
      '3' means Fête Suprème Tierce
      '4' means Fête Suprème Quarte
      'v' means Vacuation
  • is_imaginary

    Returns true or false indicating whether the datetime object represents an imaginary date.

  • set( .. )

    This method can be used to change the local components of a date time, or its locale. This method accepts any parameter allowed by the new() method.

  • truncate( to => ... )

    This method allows you to reset some of the local time components in the object to their "zero" values. The "to" parameter is used to specify which values to truncate, and it may be one of "year", "month", or "day".

  • add_duration( $duration_object )

    This method adds a DateTime::Duration to the current datetime. See the DateTime::Duration docs for more detais.

  • add( DateTime::Duration->new parameters )

    This method is syntactic sugar around the add_duration() method. It simply creates a new DateTime::Duration object using the parameters given, and then calls the add_duration() method.

  • subtract_duration( $duration_object )

    When given a DateTime::Duration object, this method simply calls invert() on that object and passes that new duration to the add_duration method.

  • subtract( DateTime::Duration->new parameters )

    Like add(), this is syntactic sugar for the subtract_duration() method.

  • subtract_datetime( $datetime )

    This method returns a new DateTime::Duration object representing the difference between the two dates.

  • compare

      $cmp = DateTime->compare($dt1, $dt2);
      @dates = sort { DateTime->compare($a, $b) } @dates;

    Compare two DateTime objects. The semantics are compatible with Perl's sort() function; it returns -1 if $a < $b, 0 if $a == $b, 1 if $a > $b.

    Of course, since DateTime objects overload comparison operators, you can just do this anyway:

      @dates = sort @dates;


  • Adding a week to a date is exactly equivalent to adding seven days in this module because of the way DateTime::Duration is implemented. The Hunyadis are not taken into account.

  • from_epoch() and now() probably only work on Unix.


Support for this module is provided via the email list. See for more details.


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Eugene van der Pijll <>

Maintained by Philippe Bruhat (BooK) since 2014.


Copyright (c) 2003, 2004 Eugene van der Pijll. All rights reserved.


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