DateTime::Duration(3pmUser Contributed Perl DocumentatiDateTime::Duration(3pm)
NAME
DateTime::Duration - Duration objects for date math
VERSION
version 1.59
SYNOPSIS
use DateTime::Duration;
$dur = DateTime::Duration->new(
years => 3,
months => 5,
weeks => 1,
days => 1,
hours => 6,
minutes => 15,
seconds => 45,
nanoseconds => 12000,
end_of_month => 'limit',
);
my ( $days, $hours, $seconds )
= $dur->in_units( 'days', 'hours', 'seconds' );
# Human-readable accessors, always positive, but consider using
# DateTime::Format::Duration instead
$dur->years;
$dur->months;
$dur->weeks;
$dur->days;
$dur->hours;
$dur->minutes;
$dur->seconds;
$dur->nanoseconds;
$dur->is_wrap_mode;
$dur->is_limit_mode;
$dur->is_preserve_mode;
print $dur->end_of_month_mode;
# Multiply all values by -1
my $opposite = $dur->inverse;
my $bigger = $dur1 + $dur2;
my $smaller = $dur1 - $dur2; # the result could be negative
my $bigger = $dur1 * 3;
my $base_dt = DateTime->new( year => 2000 );
my @sorted
= sort { DateTime::Duration->compare( $a, $b, $base_dt ) } @durations;
if ( $dur->is_positive ) {...}
if ( $dur->is_zero ) {...}
if ( $dur->is_negative ) {...}
DESCRIPTION
This is a simple class for representing duration objects. These objects
are used whenever you do date math with DateTime.
See the How DateTime Math Works section of the DateTime documentation
for more details. The short course: One cannot in general convert
between seconds, minutes, days, and months, so this class will never do
so. Instead, create the duration with the desired units to begin with,
for example by calling the appropriate subtraction/delta method on a
DateTime object.
METHODS
Like DateTime itself, "DateTime::Duration" returns the object from
mutator methods in order to make method chaining possible.
"DateTime::Duration" has the following methods:
DateTime::Duration->new( ... )
This class method accepts the following parameters:
• years
An integer containing the number of years in the duration. This is
optional.
• months
An integer containing the number of months in the duration. This is
optional.
• weeks
An integer containing the number of weeks in the duration. This is
optional.
• days
An integer containing the number of days in the duration. This is
optional.
• hours
An integer containing the number of hours in the duration. This is
optional.
• minutes
An integer containing the number of minutes in the duration. This
is optional.
• seconds
An integer containing the number of seconds in the duration. This
is optional.
• nanoseconds
An integer containing the number of nanoseconds in the duration.
This is optional.
• end_of_month
This must be either "wrap", "limit", or "preserve". This parameter
specifies how date math that crosses the end of a month is handled.
In "wrap" mode, adding months or years that result in days beyond
the end of the new month will roll over into the following month.
For instance, adding one year to Feb 29 will result in Mar 1.
If you specify "limit", the end of the month is never crossed.
Thus, adding one year to Feb 29, 2000 will result in Feb 28, 2001.
If you were to then add three more years this will result in Feb
28, 2004.
If you specify "preserve", the same calculation is done as for
"limit" except that if the original date is at the end of the month
the new date will also be. For instance, adding one month to Feb
29, 2000 will result in Mar 31, 2000.
For positive durations, this parameter defaults to "wrap". For
negative durations, the default is "preserve". This should match
how most people "intuitively" expect datetime math to work.
All of the duration units can be positive or negative. However, if any
of the numbers are negative, the entire duration is negative.
All of the numbers must be integers.
Internally, years as just treated as 12 months. Similarly, weeks are
treated as 7 days, and hours are converted to minutes. Seconds and
nanoseconds are both treated separately.
$dur->clone
Returns a new object with the same properties as the object on which
this method was called.
$dur->in_units( ... )
Returns the length of the duration in the units (any of those that can
be passed to "DateTime::Duration->new") given as arguments. All lengths
are integral, but may be negative. Smaller units are computed from what
remains after taking away the larger units given, so for example:
my $dur = DateTime::Duration->new( years => 1, months => 15 );
$dur->in_units('years'); # 2
$dur->in_units('months'); # 27
$dur->in_units( 'years', 'months' ); # (2, 3)
$dur->in_units( 'weeks', 'days' ); # (0, 0) !
The last example demonstrates that there will not be any conversion
between units which don't have a fixed conversion rate. The only
conversions possible are:
• years <=> months
• weeks <=> days
• hours <=> minutes
• seconds <=> nanoseconds
For the explanation of why this is the case, please see the How
DateTime Math Works section of the DateTime documentation
Note that the numbers returned by this method may not match the values
given to the constructor.
In list context, "$dur->in_units" returns the lengths in the order of
the units given. In scalar context, it returns the length in the first
unit (but still computes in terms of all given units).
If you need more flexibility in presenting information about durations,
please take a look a DateTime::Format::Duration.
$dur->is_positive, $dur->is_zero, $dur->is_negative
Indicates whether or not the duration is positive, zero, or negative.
If the duration contains both positive and negative units, then it will
return false for all of these methods.
$dur->is_wrap_mode, $dur->is_limit_mode, $dur->is_preserve_mode
Indicates what mode is used for end of month wrapping.
$dur->end_of_month_mode
Returns one of "wrap", "limit", or "preserve".
$dur->calendar_duration
Returns a new object with the same calendar delta (months and days
only) and end of month mode as the current object.
$dur->clock_duration
Returns a new object with the same clock deltas (minutes, seconds, and
nanoseconds) and end of month mode as the current object.
$dur->inverse( ... )
Returns a new object with the same deltas as the current object, but
multiplied by -1. The end of month mode for the new object will be the
default end of month mode, which depends on whether the new duration is
positive or negative.
You can set the end of month mode in the inverted duration explicitly
by passing an "end_of_month" parameter to the "$dur->inverse" method.
$dur->add_duration($duration_object),
$dur->subtract_duration($duration_object)
Adds or subtracts one duration from another.
$dur->add( ... ), $dur->subtract( ... )
These accept either constructor parameters for a new
"DateTime::Duration" object or an already-constructed duration object.
$dur->multiply($number)
Multiplies each unit in the "DateTime::Duration" object by the
specified integer number.
DateTime::Duration->compare( $duration1, $duration2, $base_datetime )
This is a class method that can be used to compare or sort durations.
Comparison is done by adding each duration to the specified DateTime
object and comparing the resulting datetimes. This is necessary because
without a base, many durations are not comparable. For example, 1 month
may or may not be longer than 29 days, depending on what datetime it is
added to.
If no base datetime is given, then the result of "DateTime->now" is
used instead. Using this default will give non-repeatable results if
used to compare two duration objects containing different units. It
will also give non-repeatable results if the durations contain multiple
types of units, such as months and days.
However, if you know that both objects only consist of one type of unit
(months or days or hours, etc.), and each duration contains the same
type of unit, then the results of the comparison will be repeatable.
$dur->delta_months, $dur->delta_days, $dur->delta_minutes,
$dur->delta_seconds, $dur->delta_nanoseconds
These methods provide the information DateTime needs for doing date
math. The numbers returned may be positive or negative. This is mostly
useful for doing date math in DateTime.
$dur->deltas
Returns a hash with the keys "months", "days", "minutes", "seconds",
and "nanoseconds", containing all the delta information for the object.
This is mostly useful for doing date math in DateTime.
$dur->years, $dur->months, $dur->weeks, $dur->days, $dur->hours,
$dur->minutes, $dur->seconds, $dur->nanoseconds
These methods return numbers indicating how many of the given unit the
object represents, after having done a conversion to any larger units.
For example, days are first converted to weeks, and then the remainder
is returned. These numbers are always positive.
Here's what each method returns:
$dur->years == abs( $dur->in_units('years') )
$dur->months == abs( ( $dur->in_units( 'months', 'years' ) )[0] )
$dur->weeks == abs( $dur->in_units( 'weeks' ) )
$dur->days == abs( ( $dur->in_units( 'days', 'weeks' ) )[0] )
$dur->hours == abs( $dur->in_units( 'hours' ) )
$dur->minutes == abs( ( $dur->in_units( 'minutes', 'hours' ) )[0] )
$dur->seconds == abs( $dur->in_units( 'seconds' ) )
$dur->nanoseconds == abs( ( $dur->in_units( 'nanoseconds', 'seconds' ) )[0] )
If this seems confusing, remember that you can always use the
"$dur->in_units" method to specify exactly what you want.
Better yet, if you are trying to generate output suitable for humans,
use the "DateTime::Format::Duration" module.
Overloading
This class overloads addition, subtraction, and mutiplication.
Comparison is not overloaded. If you attempt to compare durations using
"<=>" or "cmp", then an exception will be thrown! Use the "compare"
class method instead.
SEE ALSO
datetime@perl.org mailing list
SUPPORT
Support for this module is provided via the datetime@perl.org email
list. See http://lists.perl.org/ for more details.
Bugs may be submitted at
<https://github.com/houseabsolute/DateTime.pm/issues>.
There is a mailing list available for users of this distribution,
<mailto:datetime@perl.org>.
SOURCE
The source code repository for DateTime can be found at
<https://github.com/houseabsolute/DateTime.pm>.
AUTHOR
Dave Rolsky <autarch@urth.org>
COPYRIGHT AND LICENSE
This software is Copyright (c) 2003 - 2022 by Dave Rolsky.
This is free software, licensed under:
The Artistic License 2.0 (GPL Compatible)
The full text of the license can be found in the LICENSE file included
with this distribution.
perl v5.36.0 2022-12-11 DateTime::Duration(3pm)
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