=head1 NAME

Date::Handler - Easy Date Object

=head1 SYNOPSIS

  use Date::Handler;
 
  my $date = new Date::Handler({ date => time, time_zone => 'Europe/Paris', });
  my $date = new Date::Handler({ date => [2001,04,12,03,01,55], time_zone => 'EST', });
  my $date = new Date::Handler({ date => {
						year => 2001,
						month => 4,
						day => 12,
						hour => 3,
						min => 1,
						sec => 55,
					}, time_zone => 'America/Montreal', });


   print $date;
   print "$date";
   print $date->AllInfo();

   $date->new()				Constructor
   $date->Year()			2001
   $date->Month()			1..12
   $date->Day()				1..31
   $date->Hour()			0..23
   $date->Min()				0..59
   $date->Sec()				0..59
   $date->Epoch($epoch)			Seconds since epoch (GMT)
   $date->TimeZone()			America/Montreal
   $date->TimeZoneName()		EST
   $date->LocalTime()			localtime of the object's epoch 
   $date->TimeFormat($format_string)	strftime
   $date->GmtTime()			gmtime of object's epoch
   $date->UtcTime()			same as GmtTime()
   $date->GmtOffset() 			Offset of object's TZ in seconds
   $date->MonthName()			April
   $date->WeekDay()			1..7 (1 monday)
   $date->WeekDayName()			Wednesday
   $date->FirstWeekDayOfMonth()		1..7
   $date->WeekOfMonth()			1..4
   $date->DaysInMonth()			31,30,29,28 depending on month and year.
   $date->IsLeapYear()			1 if true, 0 if false
   $date->DayLightSavings()		1 if true, 0 if false
   $date->DayOfYear()			Return the day of the year
   $date->DaysInYear()			Returns the number of days in the year.
   $date->DaysLeftInYear()		Returns the number of days remaining in the year
   $date->Array2Epoch([])			Transfer [y,m,d,h,mm,ss] to epoch time
   $date->AsScalar ()			Same as TimeFormat("%A, %B%e %Y %R (%Z)") 
   $date->AsNumber()			same as Epoch()
   $date->AsArray()			Returns [y,m,d,h,mm,ss]
   $date->AsHash()			Returns { year => y, month => m, day => d, hour => h, min => mm, sec => ss }
   $date->AllInfo()			Returns a string containing all of the Object's related information.
   

   my $delta = new Date::Handler::Delta([3,1,10,2,5,5]);
   my $delta = new Date::Handler::Delta({
						years => 3,
						months => 1,
						days => 10,
						hours => 2,
						minutes => 5,
						seconds => 5,
					});

   $delta->new				(More information in perldoc Date::Handler::Delta)
   $delta->Months() 			Number of months in delta
   $delta->Seconds() 			Number of seconds in delta
   $delta->AsScalar() 			"%d months and %d seconds"
   $delta->AsNumber() 			"%d-%d-%d"
   $delta->AsArray()			[y,m,ss]
   $delta->AsHash()			{ months => m, seconds => ss }

   $date + $delta = Date::Handler
   $date - $delta = Date::Handler
   $date - $date2 = Date::Handler::Delta
   $date + n = (+n seconds)
   $date - n = (-n seconds)

   $delta + $delta = Date::Handler::Delta
   $delta - $delta = Date::Handler::Delta
   $delta * n = Date::Handler::Delta
   $delta / n = Date::Handler::Delta
   $delta + n = (+n seconds)
   $delta - n = (-n seconds)


   my $range = Date::Handler::Range->new({
						date => $date,
						delta => $delta,
					});
   my $range = Date::Handler::Range->new({
						date => [2001,06,08,2,00,00],
						delta => [0,0,1,0,0],
					});

   $range->new			(More info in perldoc Date::Handler::Range)
   $range->Direction()		Specifies the direction of a range ('FORWARDS' || 'BACKWARDS')
   $range->StartDate()		Start Date::Handler object for this range and direction
   $range->EndDate()		End Date::Handler object for this range and direction
   $range->Overlaps($range2)	Returns true if range overlaps range2. undef otherwise.


=head1 DESCRIPTION

Date::Handler is a container for dates that holds all the methods to transform itself
from Timezone to Timezone and format itself. This module idea comes from an original version
written by dLux (Szabó, Balázs) <dlux@kapu.hu> in his module Class::Date.

Date::Handler is implemented in pure Perl using POSIX modules, it encapsulates the environnement variable
TZ for it's time zone management so you don't have to play with it externally in the implementation.

It uses operator overloading and Delta date objects to calculates time differences.

This code is still in it's alpha stage(v0.05) and should not be used on production systems without
reviewing the actual test cases provided with this module in the Date::Handler::Test package.

=head1 IMPLEMENTATION

Using the Date::Handler is simple.

=head2 Creating the absolute Date::Handler

The new() constructor receives only one argument as a hashref:

	my $date = new Date::Handler({
				date => time,
				time_zone => 'Asia/Hong_Kong',
			});

The 'date' key of this argument can be either:

=over 3 

=item * Epoch time

=item * Anonymous array of the form: [y,m,d,h,mm,ss]

=item * A hashref of the form : { year => y,month => m, day => d, hour => h, min => mm, sec => ss }

=back 

The items in the array (or hash) of the 'date' key should follow these rules:

=over 3

=item * year	-	The year number 

=item * mon	-	The number of months since January, in the range 1 to 12.

=item * day	-	The day of the month, in the range 1 to 31.

=item * hour	-	The number of hours past midnight, in the range 0 to 23.

=item * min	-	The number of minutes after the hour, in the range 0 to 59.

=item * sec	-	The number of seconds after the minute, normally in the range 0 to 59.

=back

The 'time_zone' key represents the time zone name this date is considered in.  i.e. Africa/Dakar, EST, PST, EDT


=head2 Accessors

You can access the data inside the object using any of the provided methods.
These methods are detailed in the SYNOPSIS up above.


=head2 Modifying the object

A created Date::Handler can be modified on the fly by many ways:

=over 3

=item * Changing the time_zone of the object using TimeZone()

=item * Changing the internal date of the object using Epoch()

=item * By using operators in combination with Date::Handler::Delta objects

=back

Example:

	my $date = new Date::Handler({ date => time });
	$date->TimeZone('Asia/Tokyo');
	print "Time in tokyo: ".$date->LocalTime()."\n";
	$date->Epoch(time);
	$date->TimeZone('America/Montreal');
	print "Time in Montreal: ".$date->LocalTime()."\n";
	$date->TimeZone('GMT');
	print "Greenwich Mean Time: ".$date->LocalTime()."\n";


=head2 Operator overload special cases

The Date::Handler overloaded operator have special cases. Refer to the
SYNOPSIS to get a description of each overloaded operator's behaviour.

One special case of the overload is when adding an integer 'n' to a Date::Handler's reference. This is treated as if 'n' was in seconds. Same thing for substraction.

Example Uses of the overload:

	my $date = new Date::Handler({ date =>
					{
						year => 2001,
						month => 5,
						day => 14,
						hour => 5,
						min => 0,
						sec => 0,
					}});
	#Quoted string overload 
	print "Current date is $date\n";
	
	my $delta = new Date::Handler::Delta({ days => 5, });
	
	#'+' overload, now, $date is 5 days in the future.	
	$date += $delta;

	#Small clock. Not too accurate, but still ;)
	while(1)
	{
		#Add one second to the date. (same as $date + 1)
		$date++;
		print "$date\n";
		sleep(1);
	}




=head1 INHERITANCE

A useful way of using Date::Handler in your code is to implement that a class
that ISA Date::Handler. This way you can overload methods through the inheritance
tree and change the object's behaviour to your needs.

Here is a small example of an overloaded class that specifies a default
timezone different than the machine's timezone.

	#!/usr/bin/perl
	package My::Date::Handler;
	
	use strict;
	use vars qw(@ISA $VERSION);
	
	use Date::Handler;
	@ISA = qw(Date::Handler);
	
	use constant DEFAULT_TIMEZONE => 'Europe/Moscow';
	
	sub TimeZone
	{
		my ($self) = @_;
	
		my $time_zone = $self->SUPER::TimeZone(@_);
	
		return $time_zoneif defined $time_zone;
	
		return $self->DEFAULT_TIMEZONE();
	}	
	
	1;
	__END__


=head1 OTHER DATE::HANDLER MODULES

Here is a brief description of the other modules in this package.

=head2 Using Date::Handler::Delta objects

To go forward or backward in time with a date object, you can use
the Date::Handler::Delta objects. These objects represent a time lapse
represented in months and seconds. Since Date::Handler uses
operator overloading, you can 'apply' a Delta object on an absolute date
simply by using '+' and '-'.

Example:

	#A Delta of 1 year.
	my $delta = new Date::Handler::Delta([1,0,0,0,0,0]);

	my $date = new Date::Handler({ date => time } );

	#$newdate is now one year in the furure.
	my $newdate = $date+$delta;
	
	
Refer to the Date::Handler::Delta(1) documentation for more on Deltas.


=head2 Using Date::Handler::Range objects 

Range objects are used to define a time range using a start date and a delta object.
Can be useful to calculate recurrences of events and event overlap.

Example:
		
	A simple range for an event of 3 days:

	my $range = Date::Handler::Range->new({
							date => Date::Handler->new({ date => time() }),
							delta => Date::Handler::Delta->new([0,0,3,0,0,0]),
						});

	print "This event starts on ".$range->StartDate()." and end on ".$range->EndDate()."\n";

See perldoc Date::Handler::Range(1) for more information on how to use Date::Handler::Range objects. 


=head1 BUGS (known)

Dates after 2038 are not handled by this module yet. (POSIX)

Dates before 1970 are not handled by this module. (POSIX)

If you find bugs with this module, do not hesitate to contact the author.
Your comments and rants are welcomed :)


=head1 CVS AND BLEEDING VERSIONS

The latest developments and changes history for this module are available through cvsweb at:

http://cvs.flatlineconstruct.com/

The bleeding edge code is also available through anonymous CVS access via:

cvs -d:pserver:anoncvs@cvs.flatlineconstruct.com:/home/cvs/anon checkout Date-Handler

=head1 TODO

Add support for dynamic locale using perllocales functions. This will plugin directly with the use of strftime in the Date::Handler and provide locales.

Add a list of supported timezones in the Constants class.Just didnt around
to do it yet :) Feel free :) If you have patches, recommendations or suggestions on this module, please come forward :)

=head1 COPYRIGHT

Copyright(c) 2001 Benoit Beausejour <bbeausej@pobox.com>

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

Portions Copyright (c) Philippe M. Chiasson <gozer@cpan.org>

Portions Copyright (c) Szabó, Balázs <dlux@kapu.hu>

Portions Copyright (c) Larry Rosler 


=head1 AUTHOR

Benoit Beausejour <bbeausej@pobox.com>

=head1 SEE ALSO

Class::Date(1).
Time::Object(1).
Date::Calc(1).
perl(1).

=cut

