Provided by: libdatetime-perl_1.65-1build2_amd64 bug

NAME

       DateTime::Duration - Duration objects for date math

VERSION

       version 1.65

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 - 2023 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.