man Date::Manip (3): Date manipulation routines

DESCRIPTION

Date::Manip is a series of modules designed to make any common date/time operation easy to do. Operations such as comparing two times, determining a date a given amount of time from another, or parsing international times are all easily done. It deals with time as it is used in the Gregorian calendar (the one currently in use) with full support for time changes due to daylight saving time.

From the very beginning, the main focus of Date::Manip has been to be able to do ANY desired date/time operation easily. Many other modules exist which may do a subset of these operations quicker or more efficiently, but no other module can do all of the operations available in Date::Manip.

Since many other date/time modules exist, some of which may do the specific operation(s) you need faster, be sure to read ``SHOULD I USE DATE::MANIP'' in Date::Manip::Misc before deciding which of the Date and Time modules from CPAN is for you. However, if you want one module to do it all, Date::Manip is the one to use.

Date::Manip has functionality to work with several fundamental types of data.

dates: The word date is used extensively here and is somewhat misleading. In Date::Manip, a date consists of three pieces of information: a calendar date, a time of day, and time zone information. Calendar dates and times are fully handled. Time zones are handled as well, but depending on how you use Date::Manip, there may be some limitations as discussed below.
delta: A delta is an amount of time (i.e. the amount of time between two different dates). A delta refers only to an amount of time. It includes no information about a starting or ending date/time. Most people will think of a delta as an amount of time, but the term 'time' is already used so much in this module that I didn't want to use it here in order to avoid confusion.
recurrence: A recurring event is something which occurs on a regular recurring basis.
holidays and events: Holidays and events are basically named dates or recurrences.

Among other things, Date::Manip allow you to:

*: Enter a date in practically any format you choose.
*: Compare two dates, entered in widely different formats to determine which is earlier.
*: Extract any information you want from a date using a format string similar to the Unix date command.
*: Determine the amount of time between two dates, or add an amount of time to a date to get a second date.
*: Work with dates with dates using international formats (foreign month names, 12/10/95 referring to October rather than December, etc.).
*: To find a list of dates where a recurring event happens.

Each of these tasks is trivial (one or two lines at most) with this package.

VERSION 5 AND VERSION 6

Date::Manip version 6.00 was a complete rewrite of the module (for more information, please refer to the Date::Manip::Changes5to6 document). The rewrite made use of features introduced in perl 5.10 which made the date parsing routines significantly more robust. However, since not everyone has access to a new version of perl where Date::Manip is needed, the Date::Manip distribution actually includes two different versions of the module. It includes the older (5.xx) release and the newer (6.xx) release.

In addition, the 6.xx release was written with both a functional and an object-oriented interface, so there are actually three different ways to use Date::Manip (though only one is available if you have a version of perl older than 5.10).

For those who still run an older version of perl, the 5.xx functional interface is still available. It is known to work with perl 5.6 (and probably works with even older versions of perl). There are some limitations to this as described below.

Version 6.xx was rewritten as a series of object-oriented modules, but a functional interface (which is mostly backward compatible with the version 5 functional interface) is included. The functional interface is simply wrapper functions which call the OO modules.

A more detailed description of each interface is included below (to help you decide which interface is right for you). If you already know which interface you want to use, just go to the ``SEE ALSO'' section below for instructions on using each interface.

It should be noted that all three interfaces will be installed, but they will only all be usable with a recent version of perl.

FUNCTIONAL INTERFACE (VERSION 5)

When using a version of perl older than 5.10, this is the only interface available. This interface is documented in the ``Date::Manip::DM5 document''. This interface has several weaknesses that need to be understood when using it:

Limited Support

The version 5 functional interface is no longer being developed, and only limited support is available for it.

As of December 2012, no development will be done, and I will not correct any remaining bugs in version 5. If a patch is supplied by someone else to fix bugs, I will apply it, provided it applies cleanly, and the resulting code continues to pass all tests. I will not apply patches to add features.

I will continue to distribute version 5 for several years. I do not have a date in mind where version 5 will be removed.

Limited Time Zone Support

Time zone support is extremely limited, and is often broken. The lack of good time zone support was the primary reason for rewriting Date::Manip .

Time zone information for 5.xx is now automatically generated from the 6.xx time zone list, and every time time zones are updated in 6.xx, the 5.xx release will be similarly updated.

Prior to the release of 6.00, time zones were added manually to Date::Manip upon request. Since time zone information in 5.xx is now automatically generated, I no longer take requests for time zones.

The version 5 interface does not handle daylight saving time changes properly.

Performance Issues

Considerable time has been spent speeding up Date::Manip, and fairly simple benchmarks show that version 6 is around twice as fast as version 5.

Feel free to email me concerns and comments.

FUNCTIONAL INTERFACE (VERSION 6)

The version 6 functional interface is almost completely identical to the version 5 functional interface, except that it uses the object-oriented modules to do all the real work.

Time zone support is greatly improved, but is still somewhat limited. Since the version 6 interface is backward compatible, dates do not store time zone information in them, so the programmer is responsible for keeping track of what time zone each date is in. If you want full access to the time zone support offered in Date::Manip, you have to use the object-oriented interface.

For the most part, scripts written for older versions of Date::Manip will continue to work (and scripts written for the version 6 functional interface will run with the version 5 interface), however in a few cases, you may need to modify your scripts. Please refer to the Date::Manip::Migration5to6 document for a list of changes which may be necessary.

OBJECT-ORIENTED INTERFACE

As of 6.00, Date::Manip consists of a set of OO modules. Each have their own document (see the ``SEE ALSO'' section below).

The OO interface consists of the following modules: Date::Manip::Date, Date::Manip::Delta, Date::Manip::Recur, Date::Manip::TZ, and Date::Manip::Base.

The object-oriented interface is the only way to get the full functionality of Date::Manip. It fully support time zones (and daylight saving time).

SELECTING AN INTERFACE

If you are running an older version of perl, the version 5 functional interface is the only one available to you, and it will automatically be used.

If you are running a newer version of perl (5.10 or higher), you can use the object-oriented modules by loading them directly, or you can use a functional interface.

If you use a functional interface, it will default to the version 6 interface, but you can choose to run the version 5 interface in one of three ways:

Use the default functional interface

By including:

   use Date::Manip;

in your script, one of the functional interfaces will be loaded. If you are running a version of perl older than 5.10, it will automatically be the version 5 interface. If you are running a newer version of perl, it will automatically load the version 6 interface.

DATE_MANIP ENVIRONMENT VARIABLE

By setting the DATE_MANIP environment variable to 'DM5' before running the perl script, the version 5 interface will be used.

Date::Manip::Backend VARIABLE

Alternately, you can set the Date::Manip::Backend variable to be 'DM5' before loading the module. Typically, this will be done in the following way:

   BEGIN {
        $Date::Manip::Backend = 'DM5';
   }
   use Date::Manip;

Once a functional interface is loaded, you cannot switch between the version 5 and version 6 interfaces.

A description of the functional interfaces:

Date::Manip::DM5: The version 5 functional interface
Date::Manip::DM6: The version 6 functional interface

Date::Manip objects and configuration

An introduction to the Date::Manip classes used by the object-oriented interface and how to configure them:

Date::Manip::Objects: An overview of the various Date::Manip modules, and how to use them.
Date::Manip::Config: Information for configuring Date::Manip

Date::Manip object-oriented modules

These are the modules for using the object-oriented interface.

Date::Manip::Obj: This is the base class. All other classes listed here inherit the methods defined in this class.
Date::Manip::Base: A module for doing low-level date operations.
Date::Manip::TZ: A module for working with time zones.
Date::Manip::Date: The module for working with dates.
Date::Manip::Delta: The module for working with deltas (amount of time).
Date::Manip::Recur: The module for working with recurrences (recurring dates).

Timezone information

Date::Manip::DM5abbrevs: Time zone abbreviations used in the version 5 interface.
Date::Manip::Zones: Time zone data included in Date::Manip used in the version 6 interfaces.

Miscellaneous information:

Date::Manip::Calc: Detailed information on how date calculations are done.
Date::Manip::Holidays: Information on defining and using holidays and events.
Date::Manip::ConfigFile: A sample config file.
Date::Manip::Lang: Information about the languages supported by Date::Manip and how to add a new language.
Date::Manip::Lang::english
Date::Manip::Lang::catalan
Date::Manip::Lang::danish
Date::Manip::Lang::dutch
Date::Manip::Lang::finnish
Date::Manip::Lang::french
Date::Manip::Lang::german
Date::Manip::Lang::italian
Date::Manip::Lang::norwegian
Date::Manip::Lang::polish
Date::Manip::Lang::portugue
Date::Manip::Lang::romanian
Date::Manip::Lang::russian
Date::Manip::Lang::spanish
Date::Manip::Lang::swedish
Date::Manip::Lang::turkish: A description of the parseable words in each language currently supported by Date::Manip.

Information about the module and administrative things:

Date::Manip::Migration5to6: Information on changes necessary to scripts when upgrading from 5.xx to 6.xx.
Date::Manip::Changes5: Change log for Date::Manip 5.xx
Date::Manip::Changes5to6: Differences between version 5.xx and 6.00 (including information on upgrading); this contains more details than the Migration5to6 document.
Date::Manip::Changes6: Change log for Date::Manip 6.xx
Date::Manip::Misc: Miscellaneous information about Date::Manip (who should use it; acknowledgments).
Date::Manip::History: Musings on the history of Date::Manip written around it's 20th birthday.
Date::Manip::Problems: Common problems and instructions for reporting bugs.
Date::Manip::Examples: Examples of how to use Date::Manip.

LICENSE

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

AUTHOR

Sullivan Beck ([email protected])