# Copyright (c) 1995-2021 Sullivan Beck. All rights reserved.
# This program is free software; you can redistribute it and/or modify it
# under the same terms as Perl itself.

=pod

=head1 NAME

Date::Manip - Date manipulation routines

=head1 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.

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

=over 4

=item B<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 (year, month, day), a time of day (hour, minute,
second), 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.

=item B<delta>

A delta is an amount of time (i.e. the amount of time between two
different dates).  Think of it as the duration of an event or the
amount of time between two 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.

=item B<recurrence>

A recurring event is something which occurs on a regular recurring
basis.

=item B<holidays> and B<events>

Holidays and events are basically named dates or recurrences.

=back

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

=over 4

=item B<*>

Enter a date in practically any format you choose.

=item B<*>

Compare two dates, entered in widely different formats to determine
which is earlier.

=item B<*>

Extract any information you want from a date using a format string
similar to the Unix date command.

=item B<*>

Determine the amount of time between two dates, or add an amount of
time (a delta) to a date to get a second date.

=item B<*>

Work with dates using international formats (foreign month
names, 12/10/95 referring to October rather than December, etc.).

=item B<*>

Convert dates from one timezone to another.

=item B<*>

To find a list of dates where a recurring event happens.

=back

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

=head1 HOW TO USE DATE::MANIP

There are three different ways to use Date::Manip .  There are three
interfaces (version 5 functional interface, version 6 functional, and
version 6 object-oriented).  A complete description of each is
included in the L<Date::Manip::Interfaces> document.  The recommended
(and the only one with access to the full functionality of the module)
is using the Object-Oriented interface.

=head1 SEE ALSO

Because Date::Manip performs so many operations, the documentation is
extensive.  It includes the following documents:

=head2 Information about the different interfaces

Read this for a detailed description of each of the interfaces,
including information on how to choose and use the interface
best suited to your situation.

=over 4

=item L<Date::Manip::Interfaces>

A complete description of the functional interfaces available.  NOTE:
it is recommended that you use the OO interface wherever possible
as the functional interfaces have some imitations.

=back

=head2 A description of the functional interfaces:

=over 4

=item L<Date::Manip::DM5>

The version 5 functional interface

=item L<Date::Manip::DM6>

The version 6 functional interface

=back

=head2 Objects and configuration

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

=over 4

=item L<Date::Manip::Objects>

An overview of the various Date::Manip modules, and how to use them.

=item L<Date::Manip::Config>

Information for configuring Date::Manip

=back

=head2 Date::Manip object-oriented modules

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

=over 4

=item L<Date::Manip::Obj>

This is the base class.  All other classes listed here inherit the
methods defined in this class.

=item L<Date::Manip::Base>

A module for doing low-level date operations.

=item L<Date::Manip::TZ>

A module for working with time zones.

=item L<Date::Manip::Date>

The module for working with dates.

=item L<Date::Manip::Delta>

The module for working with deltas (amount of time).

=item L<Date::Manip::Recur>

The module for working with recurrences (recurring dates).

=back

=head2 Timezone information

=over 4

=item L<Date::Manip::DM5abbrevs>

Time zone abbreviations used in the version 5 interface.

=item L<Date::Manip::Zones>

Time zone data included in Date::Manip used in the version 6
interfaces.

=back

=head2 Miscellaneous information:

=over 4

=item L<Date::Manip::Calc>

Detailed information on how date calculations are done.

=item L<Date::Manip::Holidays>

Information on defining and using holidays and events.

=item L<Date::Manip::ConfigFile>

A sample config file.

=item L<Date::Manip::Lang>

Information about the languages supported by Date::Manip and how
to add a new language.

=item L<Date::Manip::Lang::english>

=item L<Date::Manip::Lang::catalan>

=item L<Date::Manip::Lang::danish>

=item L<Date::Manip::Lang::dutch>

=item L<Date::Manip::Lang::finnish>

=item L<Date::Manip::Lang::french>

=item L<Date::Manip::Lang::german>

=item L<Date::Manip::Lang::italian>

=item L<Date::Manip::Lang::norwegian>

=item L<Date::Manip::Lang::polish>

=item L<Date::Manip::Lang::portugue>

=item L<Date::Manip::Lang::romanian>

=item L<Date::Manip::Lang::russian>

=item L<Date::Manip::Lang::spanish>

=item L<Date::Manip::Lang::swedish>

=item L<Date::Manip::Lang::turkish>

A description of the parseable words in each language currently
supported by Date::Manip.

=back

=head2 Information about the module and administrative things:

=over 4

=item L<Date::Manip::Migration5to6>

Information on changes necessary to scripts when upgrading from
5.xx to 6.xx.

=item L<Date::Manip::Changes5>

Change log for Date::Manip 5.xx

=item L<Date::Manip::Changes5to6>

Differences between version 5.xx and 6.00 (including information
on upgrading); this contains more details than the Migration5to6
document.

=item L<Date::Manip::Changes6>

Change log for Date::Manip 6.xx

=item L<Date::Manip::Misc>

Miscellaneous information about Date::Manip (who should use it;
acknowledgments).

Since many other date/time modules exist, some of which may do the
specific operation(s) you need faster, be sure to read
L<Date::Manip::Misc/"SHOULD I USE DATE::MANIP"> 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.

=item L<Date::Manip::History>

Musings on the history of Date::Manip written around it's
20th birthday.

=item L<Date::Manip::Problems>

Common problems and instructions for reporting bugs.

=item L<Date::Manip::Examples>

Examples of how to use Date::Manip.

=back

=head1 LICENSE

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

=head1 AUTHOR

Sullivan Beck (sbeck@cpan.org)

=cut
