Date::Gregorian - Gregorian calendar
====================================

Copyright (c) 1999-2019, Martin Becker <hasch-cpan-mp (at) cozap.com>.

Version
-------

This is Version 0.13 of Date::Gregorian.

DLSIP status
------------

bdpOp (beta, developer, perl, object-oriented, Standard-Perl)

License
-------

This package is free software; you can distribute it and/or modify it
under the terms of the Artistic License 2.0 (see LICENSE file).

This package is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Description
-----------

Date::Gregorian performs date calculations, similar to Date::Calc
by Steffen Beyer.  However, it has a pure object-oriented interface,
it does not use C code, and it extends the Gregorian calendar beyond
some configurable date in the past by its predecessor, the Julian
calendar.  See the inline POD documentation for more details.

Y2K compliance
--------------

This package does not use nor permit two-digit abbreviations for
four-digit year numbers anywhere.  In fact, it is designed to deal
with dates in many different centuries.

Y2038 compliance
----------------

This package uses perl builtin functions gmtime and localtime for
conversions to and from timestamps.  With recent perls, these functions
can handle timestamps exceeding the 32-bit signed integer range, and
thus should work well beyond January 19, 2038.

Y6M compliance
--------------

As this package uses perl integer arithmetic for Julian day numbers,
perls with an NV size of only 4 will hit an integer overflow at some
time between 5,800,000 and 5,900,000 CE.  We recommend switching to a
64-bit integer perl before then.

Prerequisites
-------------

Perl 5.

Installation
------------

perl Makefile.PL
make
make test
make install

Test customization
------------------

Some tests depend on assumptions about the current local timezone
during testing and will not always be meaningful.  These tests can
be disabled by setting WITHOUT_DATE_GREGORIAN_LOCALTIME_TESTS=1 in
the environment or on the make test command line.

Changes
-------

Since its first release, no major changes have been made to the
module's basic interface.  Version 0.07 finally introduced the
Date::Gregorian::Business extension.  Version 0.09 introduced
iterators.  Version 0.10 introduced limited DateTime interoperability.
For a detailed history of changes, see the Changes file.

Ongoing development
-------------------

The oversimplifying Date::Gregorian::Exact extension has been
abandoned.  Look into the DateTime suite of modules for a more
comprehensive approach to handling timestamps and localization.

More samples of business calendars and better ways to define even
more of them will be added in the future.

Fractional business days are no longer supported.
They had been an experimental feature up to version 0.12.

Eventually, the essentials of Date::Gregorian::Business might
be put to work in a proper DateTime extension.

A couple of API additions are scheduled for version 1.00.
Old code should continue to work, though.

More suggestions are welcome.