Date::ICal::Duration - durations in iCalendar format, for math purposes.


Date::ICal::Duration - durations in iCalendar format, for math purposes.


$Revision: 1.61 $


    use Date::ICal::Duration;
    $d = Date::ICal::Duration->new( ical => '-P1W3DT2H3M45S' );
    $d = Date::ICal::Duration->new( weeks => 1, 
                                    days => 1,
                                    hours => 6,
                                    minutes => 15,
                                    seconds => 45);
    # a one hour duration, without other components
    $d = Date::ICal::Duration->new( seconds => "3600");
    # Read-only accessors:
    # TODO: Resolve sign() discussion from rk-devel and update synopsis.

    $d->as_seconds ();   # returns just seconds
    $d->as_elements ();  # returns a hash of elements, like the accessors above
    $d->as_ical();       # returns an iCalendar duration string


This is a trivial class for representing duration objects, for doing math in Date::ICal


Rich Bowen, and the Reefknot team (

Last touched by $Author: rbowen $


Date::ICal::Duration has the following methods available:


A new Date::ICal::Duration object can be created with an iCalendar string :

    my $ical = Date::ICal::Duration->new ( ical => 'P3W2D' );
    # 3 weeks, 2 days, positive direction
    my $ical = Date::ICal::Duration->new ( ical => '-P6H3M30S' );
    # 6 hours, 3 minutes, 30 seconds, negative direction

Or with a number of seconds:
    my $ical = Date::ICal::Duration->new ( seconds => "3600" );
    # one hour positive

Or, better still, create it with components

    my $date = Date::ICal::Duration->new ( 
                           weeks => 6, 
                           days => 2, 
                           hours => 7,
                           minutes => 15,
                           seconds => 47,
                           sign => "+"

The sign defaults to ``+'', but ``+'' and ``-'' are legal values.



#{{{ sub new

sub new { my ($class, %args) = @_; my $verified = {}; my $self = {}; bless $self, $class;

    my $seconds_only = 1;    # keep track of whether we were given length in seconds only
    $seconds_only = 0 unless (defined $args{'seconds'});
    # If one of the attributes is negative, then they all must be
    # negative. Otherwise, we're not sure what this means.
    foreach (qw(hours minutes seconds days weeks)) {
        if (defined($args{$_}) )   {
            # make sure this argument is all digits, optional - sign
            if ($args{$_} =~ m/-?[0-9]+$/) { 
                if ($args{$_} < 0) {
                    $args{sign} = '-';
                    $args{$_} = abs($args{$_});
                $verified->{$_} = $args{$_};
                unless ($_ eq 'seconds') {
                    $seconds_only = 0;
            } else {
                carp ("Parameter $_ contains non-numeric value " . $args{$_} . "\n");
    if (defined ($args{sign}) ) {
        # make sure this argument + or -
        if ($args{sign} =~ m/[+-]/) {
            # if so, assign it
            $self->{sign} = ($args{sign} eq "+") ? 1 : -1;
            $verified->{sign} = ($args{sign} eq "+") ? '+' : '-';
        } else {
            carp ("Parameter sign contains a value other than + or - : "
                . $args{sign} . "\n");

    # If a number is given, convert it to hours, minutes, and seconds,
    # but *don't* extract days -- we want it to represent an absolute
    # amount of time, regardless of timezone
    if ($seconds_only) { # if we were given an integer time_t
    } elsif (defined ($args{'ical'}) ) {   
        # A standard duration string
        #warn "setting from ical\n";
    } elsif (not $seconds_only) {
        #warn "setting from components";
        #use Data::Dumper; warn Dumper $verified;

    return undef unless %args;

    return $self;


# Accessors {{{

sign, weeks, days, hours, minutes, seconds

Read-only accessors for the elements of the object.


Returns the duration in raw seconds.

WARNING -- this folds in the number of days, assuming that they are always 86400 seconds long (which is not true twice a year in areas that honor daylight savings time). If you're using this for date arithmetic, consider using the add() method from a the Date::ICal manpage object, as this will behave better. Otherwise, you might experience some error when working with times that are specified in a time zone that observes daylight savings time.


    $days = $duration->as_days;

Returns the duration as a number of days. Not to be confused with the days method, this method returns the total number of days, rather than mod'ing out the complete weeks. Thus, if we have a duration of 33 days, weeks will return 4, days will return 5, but as_days will return 33.

Note that this is a lazy convenience function which is just weeks*7 + days.


Return the duration in an iCalendar format value string (e.g., ``PT2H0M0S'')


Returns the duration as a hashref of elements.



Internally, we store 3 data values: a number of days, a number of seconds (anything shorter than a day), and a sign (1 or -1). We are assuming that a day is 24 hours for purposes of this module; yes, we know that's not completely accurate because of daylight-savings-time switchovers, but it's mostly correct. Suggestions are welcome.

NOTE: The methods below SHOULD NOT be relied on to stay the same in future versions.

_set_from_ical ($self, $duration_string)

Converts a RFC2445 DURATION format string to the internal storage format.

_parse_ical_string ($string)

Regular expression for parsing iCalendar into usable values.

_set_from_components ($self, $hashref)

Converts from a hashref to the internal storage format. The hashref can contain elements ``sign'', ``weeks'', ``days'', ``hours'', ``minutes'', ``seconds''.

_set_from_ical ($self, $num_seconds)

Sets internal data storage properly if we were only given seconds as a parameter.


Return an arrayref to hours, minutes, and second components, or undef if nsecs is undefined. If given an arrayref, computes the new nsecs value for the duration.


Return an arrayref to weeks and day components, or undef if ndays is undefined. If Given an arrayref, computs the new ndays value for the duration.

 Date::ICal::Duration - durations in iCalendar format, for math purposes.