DateTime::Format::Epoch(3pm)				User Contributed Perl Documentation			      DateTime::Format::Epoch(3pm)

NAME

       DateTime::Format::Epoch - Convert DateTimes to/from epoch seconds

SYNOPSIS

	 use DateTime::Format::Epoch;

	 my $dt = DateTime->new( year => 1970, month => 1, day => 1 );
	 my $formatter = DateTime::Format::Epoch->new(
			     epoch	    => $dt,
			     unit	    => 'seconds',
			     type	    => 'int',	 # or 'float', 'bigint'
			     skip_leap_secondss => 1,
			     start_at	    => 0,
			     local_epoch    => undef,
			 );

	 my $dt2 = $formatter->parse_datetime( 1051488000 );
	  # 2003-04-28T00:00:00

	 $formatter->format_datetime($dt2);
	  # 1051488000

DESCRIPTION

       This module can convert a DateTime object (or any object that can be converted to a DateTime object) to the number of seconds since a given
       epoch.  It can also do the reverse.

METHODS

       o   new( ... )

	   Constructor of the formatter/parser object. It can take the following parameters: "epoch", "unit", "type", "skip_leap_seconds",
	   "start_at", "local_epoch" and "dhms".

	   The epoch parameter is the only required parameter. It should be a DateTime object (or at least, it has to be convertible to a DateTime
	   object). This datetime is the starting point of the day count, and is usually numbered 0. If you want to start at a different value,
	   you can use the start_at parameter.

	   The unit parameter can be "seconds", "milliseconds, "microseconds" or "nanoseconds". The default is "seconds". If you need any other
	   unit, you must specify the number of units per second. If you specify a number of units per second below 1, the unit will be longer
	   than a second.  In this way, you can count days: unit => 1/86_400.

	   The type parameter specifies the type of the return value. It can be "int" (returns integer value), "float" (returns floating point
	   value), or "bigint" (returns Math::BigInt value). The default is either "int" (if the unit is "seconds"), or "bigint" (if the unit is
	   nanoseconds).

	   The default behaviour of this module is to skip leap seconds. This is what (most versions of?) UNIX do. If you want to include leap
	   seconds, set skip_leap_seconds to false.

	   Some operating systems use an epoch defined in the local timezone of the computer. If you want to use such an epoch in this module, you
	   have two options. The first is to submit a DateTime object with the appropriate timezone. The second option is to set the local_epoch
	   parameter to a true value. In this case, you should submit an epoch with a floating timezone. The exact epoch used in "format_datetime"
	   will then depend on the timezone of the object you pass to "format_datetime".

	   Most often, the time since an epoch is given in seconds. In some circumstances however it is expressed as a number of days, hours,
	   minutes and seconds. This is done by NASA, for the so called Mission Elapsed Time. For example, 2/03:45:18 MET means it has been 2
	   days, 3 hours, 45 minutes, and 18 seconds since liftoff. If you set the dhms parameter to true, format_datetime returns a four element
	   list, containing the number of days, hours, minutes and seconds, and parse_datetime accepts the same four element list.

       o   format_datetime($datetime)

	   Given a DateTime object, this method returns the number of seconds since the epoch.

       o   parse_datetime($secs)

	   Given a number of seconds, this method returns the corresponding DateTime object.

BUGS

       I think there's a problem when you define a count that does not skip leap seconds, and uses the local timezone. Don't do that.

SUPPORT

       Support for this module is provided via the datetime@perl.org email list. See http://lists.perl.org/ for more details.

AUTHOR

       Eugene van der Pijll <pijll@gmx.net>

COPYRIGHT

       Copyright (c) 2003-2006 Eugene van der Pijll.  All rights reserved.  This program is free software; you can redistribute it and/or modify
       it under the same terms as Perl itself.

SEE ALSO

       DateTime

       datetime@perl.org mailing list

perl v5.10.1							    2007-12-03					      DateTime::Format::Epoch(3pm)