Date::Manip(3)

NAME
Date::Manip - 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 data 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 the section SHOULD I USE DATE::MANIP in the Date::Manip::Misc document 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.

    I will continue to do limited bug fixes provided they do not require a lot of changes. Anything to do with time zone handling will not be fixed, and other problems (especially those that have already been fixed in the 6.xx release) may not be patched if they require significant changes to 5.xx.

    Limited bug fixes will be supported until December 2012. At that point, I will reevaluate things and decide whether or not to continue this or not. My prediction is that, at that point, I will cease providing bug fixes for the 5.xx release entirely.

    Whether or not I continue to do bug fixes, I will continue to distribute the version 5 functional interface until at least December 2013. After that, I will evaluate the need for a perl 5.6/5.8 version of Date::Manip in order to decide whether or not to continue distributing it.

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.

No Further Development
    No functionality will be added to 5.xx .

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.

SEE ALSO
The following documents describe various parts of Date::Manip. The following documents describe the basic operation of the Date::Manip package:

A description of the functional interfaces:

  Date::Manip::DM5        - the version 5 functional interface
  Date::Manip::DM6        - the version 6 functional interface

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

The methods available in each class:

  Date::Manip::Obj        - base class (modules listed below
                            inherit the methods defined in this
                            class)
  Date::Manip::Base       - module for doing low-level date
                            operations
  Date::Manip::TZ         - module for working with time zones
  Date::Manip::Date       - date operations
  Date::Manip::Delta      - delta operations
  Date::Manip::Recur      - recurrence operations

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 interface and
                            the object-oriented interface

Miscellaneous information:

  Date::Manip::Calc       - detailed informaion on how date
                            calculations are done
  Date::Manip::Holidays   - information on defining and using
                            holidays and events
  Date::Manip::ConfigFile - sample config file
  Date::Manip::Lang       - information about the languages
                            supported by Date::Manip and how
                            to add a new language

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;
                            acknowledgements)
  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 (sbeck@cpan.org)