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Date-Handler-0.19
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/ Date::Handler

NAME

Date::Handler - Easy but complete date object (0.18)

SYNOPSIS

  use Date::Handler;
 
  my $date = new Date::Handler({ date => time, time_zone => 'Europe/Paris', locale => 'french'});
  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/Los_Angeles', 
					locale => 'en_US', 
				});

   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,EST,PST and so on
   $date->Locale()			french, en_US, fr_FR, spanish and so on
   $date->SetLocale(locale)		Set the locale to the argument, returns locale or undef.
   $date->LocaleRealName()		Current locale's real name on the system
   $date->TimeZoneName()		EST, PST and so on
   $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.

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. Date::Handler also supports localisation using POSIX where available.

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

IMPLEMENTATION

Using the Date::Handler is simple.

Creating the absolute Date::Handler

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

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


my $date = new Date::Handler({
			date => time(),
			time_zone => 'America/Los_Angeles',
			locale => 'spanish',
		});

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

  • Epoch time

  • Anonymous array of the form: [y,m,d,h,mm,ss]

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

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

  • year - The year number

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

  • day - The day of the month, in the range 1 to 31.

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

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

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

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

The optional 'locale' key represents the locale used to represent this date. i.e. spanish, japananese, de_DE , fr_FR

You can also pass an 'intuitive_day' key to the constructor. This is described in the "USING INTUITIVE MONTH CALCULATIONS" section.

Accessors

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

Modifying the object

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

  • Changing the time_zone of the object using TimeZone()

  • Changing the object's locale on the fly using SetLocale()

  • Changing the internal date of the object using Epoch()

  • By using operators in combination with Date::Handler::Delta objects

Examples:

#Start off with a basic object for NOW.	
my $date = new Date::Handler({ date => time });

#Go through the time zones...
$date->TimeZone('Asia/Tokyo');
print "Time in tokyo: ".$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";

# Go through some locales...

$date->SetLocale('french');
print "Time in ".$date->Locale().": ".$date."\n";
$date->SetLocale('deutsch');
print "Time in ".$date->Locale().": ".$date."\n";
$date->SetLocale('spanish');
print "Time in ".$date->Locale().": ".$date."\n";

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);
}

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';
use consant DEFAULT_LOCALE => 'russian';
	
sub TimeZone
{
	my ($self) = @_;

	my $time_zone = $self->SUPER::TimeZone(@_);

	return $time_zone if defined $time_zone;

	return $self->DEFAULT_TIMEZONE();
}	

1;
__END__

USING INTUITIVE MONTH CALCULATIONS (off by default)

Date::Handler contains a feature by witch a date handler object can use intuitive month calculation. This means that Date::Handler will compensate for month overflows during delta operations.

For example, if you have a date handler that is 2002/01/30, and you add to it a delta of 1 month, standard Date::Handler object will give you a new object that is 2002/03/02. This is because POSIX will compensate for the month overflow and add 2 days to the date because February does not have a 29 or 30th in 2002. Date::Handler can compensate for that by using the INTUITIVE_MONTH_CALCULATIONS constant. (this is turned off by default).

This constant can be turned on during overloading (inheritance):

use constant INTUITIVE_MONTH_CALCULATIONS => 1;

Turning this constant on will tell Date::Handler to follow track of month overflow during operations. This will make it so that adding a month to 2002/01/30 will bring you to 2002/02/28. Adding another month to this will bring you (with intuition) to 2002/03/30, because Date::Handler keeps track of the "intuitive" day of the month.

Using INTUITIVE_MONTH_CALCULATIONS will also make it possible to pass an "intuitive_day" key to the new() constructor in order to simulate a previous addition.

i.e.
	
my $date = Date::Handler->new({ 
			date => [2002,02,28,1,0,0,0], 
			time_zone => 'America/Montreal',
			intuitive_day => '30',
});

my $onemonth = Date::Handler::Delta->new([0,1,0,0,0,0]);

print ($date + $onemonth)."\n";

In this example, the start date of 2002/02/28 with intuitive_day set to 30 will make it so that adding 1 month to the date will bring us to march 30th. Note that INTUITIVE_MONTH_CALCULATIONS will only affect month/day calculations and no time modifications will be applied.

USING INTUITIVE_DST_ADJUSTMENTS (off by default)

Date::Handler provides a facility called INTUITIVE_DST_ADJUSTMENTS. This is implemented via an inherited constant, like the other options above. When INTUITIVE_DST_ADJUSTMENTS are turned on, Date::Handler will compensate for day light savings changes. For example, 2002/04/07 1AM + 1 day would give you 2002/04/08 1AM instead of 2AM. Note that INTUITIVE_DST_ADJUSTMENTS will not apply this compensation when the exact "turn over" date/time is detected. For example, 2002/04/06 2AM + 1 day would give you 2002/04/07 3AM because we don't compensate for this specific case.

USING INTUITIVE_TIME_CALCULATIONS (off by default)

Date::Handler provides yet another facility to add intuitive date calculations. By using INTUITIVE_TIME_CALCULATIONS (via inherited constant), Date::Handler will "remember" that it compensated for a DST adjustment and try to compensate for it.

For example, 2002/04/06 2AM + 1day would give you 2002/04/07 3AM. Adding a day to this date under INTUITIVE_TIME_CALCULATIONS would give you 2002/04/08 2AM because Date::Handler remembers it compensated for day light savings.

Combining INTUITIVE_DST_ADJUSTMENTS, INTUITIVE_MONTH_CALCULATIONS and INTUITIVE_TIME_CALCULATIONS will give a behaviour closer to the way humans expect the module to react.

This can be very useful to make date calculations a little more "humanized".

The intuitive "hour" can be faked by passing it to the new() constructor:

package MyDateHandler;

use strict;
use base qw(Date::Handler);

use constant INTUITIVE_DST_ADJUSTMENTS => 1;
use constant INTUITIVE_TIME_CALCULATIONS => 1;

1;

then:

my $date = MyDateHandler->new({ 
		date => [2002,04,08,5,0,0], 
		time_zone => 'America/Montreal',
		intuitive_hour => 2,
});

NOTES ON TIME ZONES, LOCALISATION AND FORMATTING

Date::Handler supports locales using POSIX setlocale() functions. The allowed values for the locale are listed (on most unix system) using the `locale -a` command. The Date::Handler defaults to "en_US" for it's locale when no locale are passed to the constructor. The constant DEFAULT_LOCALE can be overloaded to change this behaviour. Special note that the locales "english" and "en" are not implemented on most linux (Red Hat here) systems. You need to use the locale en_US, en_GB etc etc.

Date::Handler supports time zones using POSIX tzset() and tzname() functions. The allowed values for the time_zone key are listed (on linux systems) by look at the /usr/share/zoneinfo directory. The Date::Handler default to "GMT" for it's time zone when to time_zone key are passed to the constructor. The constant DEFAULT_TIME_ZONE can be overloaded to change this behaviour.

Date::Handler's formatting is provided by POSIX's strfmtime() function. The allowed parameters to the TimeFormat() method can be listed (on most unix system) using `man strftime`. By default, Date::Handler uses the format string '%c' to represent itself in most cases. The constant DEFAULT_FORMAT_STRING can be overloaded to change this behaviour.

OTHER DATE::HANDLER MODULES

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

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.

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.

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 :)

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

Please, if you use this module in a project, let me know!

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 :)

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

AUTHOR

Benoit Beausejour <bbeausej@pobox.com>

CONTRIBUTORS

  • Ethan Joffe <ethan@namimedia.com>

  • Ron Savage <ron@savage.net.au>

  • Roland Rauch <roland@rauch.com>

  • Phillippe M. Chiasson <gozer@cpan.org>

  • Jamie Letual <jamie@letual.net>

SEE ALSO

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

1 POD Error

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