Ubuntu Manpage: Date::Manip::Holidays - describes holidays and events

Provided by: libdate-manip-perl_6.90-1_all

NAME

       Date::Manip::Holidays - describes holidays and events

SYNOPSIS

       This describes the Holidays and Events sections of the config file, and how they are used.

       Holidays and events are specific days that are named. Holidays are used in business mode
       calculations, events are not. Events may be used for other calendaring operations.

HOLIDAYS

The holiday section of the config file is used to define holidays. Each line is of the
form:

STRING = HOLIDAY

HOLIDAY is the name of the holiday or it can be blank.

If HOLIDAY is blank, the holiday is unnamed, but still treated as a holiday. For example,
in the US, the day after Thanksgiving is often a work holiday though it is not named.

HOLIDAY should be unique in most cases. The only exception is if the holiday definition
is complex enough that it is impossible to describe it with one STRING. In this case,
multiple lines may be given with different values of STRING but the same value for
HOLIDAY, and in these cases, the first STRING that matches a given year will be used.
This situation is described in more detail below.

NOTE: It is not allowed to have unnamed holidays that require multiple definitions, so a
name will have to be assigned in that case.

STRING is a string which can be parsed to give a valid date. It can be any of the
following forms:

A full date
Specific holidays can be set which occur only a single time.

May 5, 2000 = A one-time-only holiday

Any format parseable by "Date::Manip::Date::parse_date" can be used.

There is one caveat to using a full date. Date::Manip assumes that most holidays will
appear once per year, so if you were to explicitly defined New Years (observed) as:

2004-12-31 = New Year's Day

then it would assume that it had found the occurrence of New Year's for 2004 when in
fact, this is the 2005 occurrence.

Full date specifications should only be used as a last resort, and probably only if
you will explicitly specify all occurrence of the holiday.

A date without a year
Some holidays occur every year on the same day. These can be defined using the simple
lines:

Jan 1 = New Year's Day
Jul 4th = Independence Day
fourth Thu in Nov = Thanksgiving

These dates must be written in a form which can be parsed as a full date by simply
adding the year to the end of the string. Please refer to the Date::Manip::Date
documentation to see what forms will work. ISO 8601 dates will not work since the year
comes first.

Any format parseable by "Date::Manip::Date::parse_date" which allows the year to be at
the end can be used.

Recurrence
The dates can be specified using recurrences:

1*0:0:0:0:0:0*EASTER = Easter
1*11:0:11:0:0:0*DWD = Veteran's Day
1*11:4:4:0:0:0 = Thanksgiving
1*11:4:4:0:0:0*FD1 = Day after Thanksgiving

In cases where you are interested in business type calculations, you'll want to define
most holidays using recurrences, since they can define when a holiday is celebrated in
the financial world. For example, Christmas might be defined as:

Dec 25 = Christmas

but if it falls on a weekend, there won't be a business holiday associated with it. It
could be defined using a recurrence:

1*12:0:24:0:0:0*DWD = Christmas

so that if Christmas falls on a weekend, a holiday will be taken on the Friday before
or the Monday after the weekend.

You can use the fully specified format of a recurrence:

1*2:0:1:0:0:0***Jan 1 1999*Dec 31 2002 = Feb 2 from 1999-2002

OTHER HOLIDAY CONSIDERATIONS

       Recurrences which change years
           It is now valid to have a recurrence defined for New Year's day which pushes the
           holiday to the previous year.

           For example, the most useful definition of New Year's day is:

              1*1:0:1:0:0:0*DWD               = New Year's Day

           which means to choose the closest working day to observe the holiday, even though this
           might mean that the holiday is observed on the previous year.

       Order of definitions is preserved
           The order of the definitions is preserved. In other words, when looking at the
           holidays for a year, previously defined holidays (in the order given in the config
           file) are correctly handled.

           As an example, if you wanted to define both Christmas and Boxing days (Boxing is the
           day after Christmas, and is celebrated in some parts of the world), and you wanted to
           celebrate Christmas on a business day on or after Dec 25, and Boxing day as the
           following work day, you could do it in one of the following ways:

              1*12:0:25:0:0:0*NWD  = Christmas
              1*12:0:26:0:0:0*NWD  = Boxing

           or

              1*12:0:25:0:0:0*NWD  = Christmas
              1*12:0:25:0:0:0*NWD  = Boxing

           Holidays go into affect the minute they are parsed which is why the second example
           works (though for clarity, the first one is preferable).  The first recurrence defined
           the first business day on or after Dec 25 as Christmas.  The second one then defines
           the business day after that as Boxing day.  Since the definitions are stored as a list
           (NOT a hash as they were in Date::Manip 5.xx), using the same recurrence twice does
           not cause a problem.

       Multiple holidays
           Having multiple holidays on a single day is allowed. As an example, you may want to
           look at New Years day as both the observed and actual holidays, so you might have:

              1*1:0:1:0:0:0*DWD               = New Year's Day (observed)
              Jan 1                           = New Year's Day

           Most of the time, both will fall on the same day, but sometimes they may differ.  In
           this example, it is important that the observed holiday be listed first.  Otherwise,
           Jan 1 will be marked as a holiday and then the observed date will check Jan 1, but
           where it is not a business day, it will move to another day (due to the DWD modifier).

           Likewise, the two holidays:

              3rd Sunday in June              = Father's Day
              Jun 17                          = Bunker Hill Day

           sometimes fall on the same day.  Using the "Date::Manip::Date::list_holidays" method
           (or the "Date_IsHoliday" function), you can get a list of all names that the date
           contains.

       Complex holiday descriptions
           Occasionally, you cannot describe a holiday using a single line.  For example, the US
           Federal Reserve banks use a complex holiday description where:

              For holidays falling on Saturday, Federal Reserve Banks
              and Branches will be open the preceding Friday. For holidays
              falling on Sunday, all Federal Reserve Banks and Branches
              will be closed the following Monday.

           Since Saturday is not a business day, the DWD modifier will not work.  For these, you
           need a more complicated definition.

           The following definitions both work:

              # Saturday
              1*1:0:1:0:0:0*NBD,BD1,IBD,FD1   = New Year's Day
              # Sunday (observed Monday)
              1*1:0:1:0:0:0*NBD,BD1,NBD,FD2   = New Year's Day
              # M-F
              1*1:0:1:0:0:0*IBD               = New Year's Day

           and

              # Saturday
              1*1:0:1:0:0:0*IW6               = New Year's Day
              # Sunday (observed Monday)
              1*1:0:1:0:0:0*IW7,FD1           = New Year's Day
              # M-F
              1*1:0:1:0:0:0*IBD               = New Year's Day

EVENTS

The Events section of the config file is similar to the Holiday section. It is used to
name certain days or times, but there are a few important differences:

Events can be assigned to any time and duration
All holidays are exactly 1 day long. They are assigned to a period of time from
midnight to midnight.

Events can be based at any time of the day, and may be of any duration.

Events don't affect business mode calculations
Unlike holidays, events are completely ignored when doing business mode calculations.

Whereas holidays were added with business mode math in mind, events were added with
calendar and scheduling applications in mind.

Every line in the events section is of the form:

EVENT = NAME

where NAME is the name of the event, and EVENT defines when it occurs and its duration.
An EVENT can be defined in the following ways:

Date
YMD
YM
Recur

Date ; Date
YMD ; YMD
YM ; YM
Date ; Delta
Recur ; Delta

Date refers to a full date/time (and is any string that can be parsed by
"Date::Manip::Date::parse"). YMD is any string which can be parsed by
"Date::Manip::Date::parse_date". YM is any string which can be parsed by the parse_date
method to give a date in the current year. Recur is a partial or fully specified
recurrence. Delta is any string that can be parsed to form a delta.

With the "Date" form, or the "Recur" form, the event starts at the time (or times)
specified by the date or recurrence, and last 1 hour long. With the "YMD" and "YM" forms,
the event occurs on the given day, and lasts all day.

With all of the two part forms ("Date;Date", "YM;YM", etc.), the event starts at the first
date and goes to the second date, or goes an amount of time specified by the delta.

The "YMD;YMD" and "YM;YM" forms means that the event lasts from the start of the first
date to the end of the second. In the Date;Date form, the event goes from the first date
to the second date inclusive. In other words, both dates are in the event. In the
"Date;Delta" and "Recur;Delta" forms, the Delta tells the length of the event. Also, in
the Date;Date form, the second date may NOT be expressed as a delta.

Currently, having an event longer than 1 year is NOT supported, but no checking is done
for this.

KNOWN BUGS

       None known.

BUGS AND QUESTIONS

       Please refer to the Date::Manip::Problems documentation for information on submitting bug
       reports or questions to the author.

LICENSE

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

AUTHOR

       Sullivan Beck (sbeck@cpan.org)