DateTi...SpanSet(3pm)

📦

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💖 NAME 💖

Hey bestie 💖 welcome to the tea on DateTime::SpanSet — straight from the User Contributed Perl Documentation corner of manual-page land (you know, that DateTi...SpanSet(3pm) header vibe). It’s the class for sets of datetime spans, and it is lowkey iconic.

✨ SYNOPSIS ✨

$spanset = DateTime::SpanSet->from_spans( spans => [ $dt_span, $dt_span ] );

$set = $spanset->union( $set2 );         # like "OR", "insert", "both"
$set = $spanset->complement( $set2 );    # like "delete", "remove"
$set = $spanset->intersection( $set2 );  # like "AND", "while"
$set = $spanset->complement;             # like "NOT", "negate", "invert"

if ( $spanset->intersects( $set2 ) ) { ...  # like "touches", "interferes"
if ( $spanset->contains( $set2 ) ) { ...    # like "is-fully-inside"

# data extraction
$date = $spanset->min;           # first date of the set
$date = $spanset->max;           # last date of the set

$iter = $spanset->iterator;
while ( $dt = $iter->next ) {
    # $dt is a DateTime::Span
    print $dt->start->ymd;   # first date of span
    print $dt->end->ymd;     # last date of span
};

🌸 DESCRIPTION 🌸

DateTime::SpanSet is the class that represents sets of datetime spans. Think: a recurring meeting that happens every Friday from 13:00–15:00 — yes, that exact vibe. 🗓️✨

This is not the same thing as a DateTime::Set, which is made of individual datetime points instead of ranges. Different species, bestie. 💅

🎀 METHODS 🎀

💫 from_spans

Creates a new span set from one or more DateTime::Span objects.

$spanset = DateTime::SpanSet->from_spans( spans => [ $dt_span ] );

🌟 from_set_and_duration

Creates a new span set from one or more DateTime::Set objects plus a duration.

That duration can be a DateTime::Duration object, or the parameters to create a new DateTime::Duration object — stuff like days, months, etc.

$spanset =
    DateTime::SpanSet->from_set_and_duration
        ( set => $dt_set, days => 1 );

🦋 from_sets

Creates a new span set from two DateTime::Set objects.

One set defines the starting dates, and the other defines the end dates.

$spanset =
    DateTime::SpanSet->from_sets
        ( start_set => $dt_set1, end_set => $dt_set2 );

The spans have the starting date closed, and the end date open, like in [$dt1, $dt2).

If an end date comes without a starting date before it, then it defines a span like (-inf, $dt).

If a starting date comes without an end date after it, then it defines a span like [$dt, inf).

🫧 empty_set

Creates a new empty set. Simple as that. 💅

🍓 is_empty_set

Returns true if the set is empty; false otherwise.

print "nothing" if $set->is_empty_set;

🧚 clone

This object method returns a replica of the given object. Copy-paste energy, but make it official. ✨

🕰️ set_time_zone( $tz )

This method accepts either a time zone object or a string that can be passed as the name parameter to DateTime::TimeZone->new(). If the new time zone’s offset is different from the old time zone, then the local time is adjusted accordingly.

If the old time zone was a floating time zone, then no adjustments to the local time are made, except to account for leap seconds. If the new time zone is floating, then the UTC time is adjusted in order to leave the local time untouched.

💖 start, min

💖 end, max

First or last dates in the set.

It is possible that the return value from these methods may be a DateTime::Infinite::Future or a DateTime::Infinite::Past object. 👀

If the set ends before a date $dt, it returns $dt. Note that in this case $dt is not a set element — but it <em>is</em> a set boundary.

These methods may return undef if the set is empty.

These methods return just a copy of the actual boundary value. If you modify the result, the set will not be modified. So go ahead and poke at the copy; the original is unbothered. 💅

🌈 duration

The total size of the set, as a DateTime::Duration object.

The duration may be infinite.

Also available as size().

🎀 span

The total span of the set, as a DateTime::Span object.

🔥 next

my $span = $set->next( $dt );

This method is used to find the next span in the set, after a given datetime or span.

The return value is a DateTime::Span, or undef if there is no matching span in the set.

🌙 previous

my $span = $set->previous( $dt );

This method is used to find the previous span in the set, before a given datetime or span.

The return value is a DateTime::Span, or undef if there is no matching span in the set.

⭐ current

my $span = $set->current( $dt );

This method is used to find the “current” span in the set, that intersects a given datetime or span. If no current span is found, then the previous span is returned.

The return value is a DateTime::SpanSet, or undef if there is no matching span in the set.

If a span parameter is given, it may happen that current returns more than one span.

🦄 closest

my $span = $set->closest( $dt );

This method is used to find the “closest” span in the set, given a datetime or span.

The return value is a DateTime::SpanSet, or undef if the set is empty.

If a span parameter is given, it may happen that closest returns more than one span.

🌸 as_list

Returns a list of DateTime::Span objects.

my @dt_span = $set->as_list( span => $span );

Just as with the iterator() method, the as_list() method can be limited by a span.

Applying as_list() to a large recurring spanset is a very expensive operation, both in CPU time and in the memory used. 😭

For this reason, when as_list() operates on large recurrence sets, it will return at most approximately 200 spans. For larger sets, and for infinite sets, as_list() will return undef.

Please note that this is explicitly not an empty list, since an empty list is a valid return value for empty sets! 💀

If you really need to extract spans from a large set, you can:

limit the set with a shorter span:

my @short_list = $large_set->as_list( span => $short_span );

use an iterator:

my @large_list;
my $iter = $large_set->iterator;
push @large_list, $dt while $dt = $iter->next;

💥 union

💥 intersection

💥 complement

Set operations may be performed not only with DateTime::SpanSet objects, but also with DateTime, DateTime::Set and DateTime::Span objects. These set operations always return a DateTime::SpanSet object.

$set = $spanset->union( $set2 );         # like "OR", "insert", "both"
$set = $spanset->complement( $set2 );    # like "delete", "remove"
$set = $spanset->intersection( $set2 );  # like "AND", "while"
$set = $spanset->complement;             # like "NOT", "negate", "invert"

🧵 intersected_spans

This method can accept a DateTime list, a DateTime::Set, a DateTime::Span, or a DateTime::SpanSet object as an argument.

$set = $set1->intersected_spans( $set2 );

The method always returns a DateTime::SpanSet object, containing all spans that are intersected by the given set.

Unlike the intersection method, the spans are not modified. See diagram below:

                          set1   [....]   [....]   [....]   [....]
                          set2      [................]

                  intersection      [.]   [....]   [.]

             intersected_spans   [....]   [....]   [....]

🫶 intersects

🫶 contains

These set functions return a boolean value.

if ( $spanset->intersects( $set2 ) ) { ...  # like "touches", "interferes"
if ( $spanset->contains( $dt ) ) { ...    # like "is-fully-inside"

These methods can accept a DateTime, DateTime::Set, DateTime::Span, or DateTime::SpanSet object as an argument.

intersects() returns 1 for true, and 0 for false. In a few cases the algorithm can’t decide if the sets intersect at all, and intersects() will return undef. 🙈

🌀 iterator / next / previous

This method can be used to iterate over the spans in a set.

$iter = $spanset->iterator;
while ( $dt = $iter->next ) {
    # $dt is a DateTime::Span
    print $dt->min->ymd;   # first date of span
    print $dt->max->ymd;   # last date of span
}

The boundaries of the iterator can be limited by passing it a span parameter. This should be a DateTime::Span object which delimits the iterator’s boundaries. Optionally, instead of passing an object, you can pass any parameters that would work for one of the DateTime::Span class’s constructors, and an object will be created for you.

Obviously, if the span you specify is not restricted both at the start and end, then your iterator may iterate forever, depending on the nature of your set. User beware! ⚠️

The next() or previous() methods will return undef when there are no more spans in the iterator.

🧭 start_set

🧭 end_set

These methods do the inverse of the from_sets method:

start_set retrieves a DateTime::Set with the start datetime of each span.

end_set retrieves a DateTime::Set with the end datetime of each span.

🗺️ map ( sub { ... } )

# example: enlarge the spans
$set = $set2->map(
    sub {
        my $start = $_->start;
        my $end = $_->end;
        return DateTime::Span->from_datetimes(
            start => $start,
            before => $end,
        );
    }
);

This method is the “set” version of Perl map.

It evaluates a subroutine for each element of the set (locally setting $_ to each DateTime::Span) and returns the set composed of the results of each such evaluation.

Like Perl map, each element of the set may produce zero, one, or more elements in the returned value.

Unlike Perl map, changing $_ does not change the original set. This means that calling map in void context has no effect.

The callback subroutine may not be called immediately. Don’t count on subroutine side-effects. For example, a print inside the subroutine may happen later than you expect.

The callback return value is expected to be within the span of the previous and the next element in the original set.

okay so, for example: given the set "[ 2001, 2010, 2015 ]", the callback result for the value 2010 is expected to be within the span "[ 2001 .. 2015 ]". iykyk ✨

grep ( sub { ... } ) — the set version of Perl grep, and it is so useful. Example first, bestie:

# example: filter out all spans happening today
my $today = DateTime->today;
$set = $set2->grep(
    sub {
        return ( ! $_->contains( $today ) );
    }
);

This method is the "set" version of Perl grep. It evaluates a subroutine for each element of the set (locally setting $_ to each DateTime::Span) and returns the set consisting of those elements for which the expression evaluated to true. big main-character energy 💅

Unlike Perl grep, changing $_ does not change the original set. This means that calling grep in void context has no effect. no cap. Changing $_ does change the resulting set.

Heads up, bestie: the callback subroutine may not be called immediately. Don't count on subroutine side-effects. For example, a print inside the subroutine may happen later than you expect. seriously, don’t rely on timing here 😭

iterate — internal method — use map or grep instead.

This function applies a callback subroutine to all elements of a set and returns the resulting set.

The parameter $_[0] to the callback subroutine is a DateTime::Span object.

If the callback returns undef, the datetime is removed from the set:

sub remove_sundays {
    $_[0] unless $_[0]->start->day_of_week == 7;
}

The callback return value is expected to be within the span of the "previous" and the "next" element in the original set.

For example: given the set "[ 2001, 2010, 2015 ]", the callback result for the value 2010 is expected to be within the span "[ 2001 .. 2015 ]".

Also heads up: the callback subroutine may not be called immediately. Don't count on subroutine side-effects. For example, a print inside the subroutine may happen later than you expect. the vibes are asynchronous, okay? 🦋

💬 SUPPORT 💬

Support is offered through the "datetime@perl.org" mailing list. come hang out 💌

Please report bugs using rt.cpan.org. bug reports are a love language 🐛

✨ AUTHOR ✨

Flavio Soibelmann Glock <fglock@gmail.com> iconic 👑

The API was developed together with Dave Rolsky and the DateTime Community. community slay 🫶

🎀 COPYRIGHT 🎀

The full text of the license can be found in the LICENSE file included with this module. legal bestie moment 📜

🔗 SEE ALSO 🔗

Set::Infinite

For details on the Perl DateTime Suite project please see <http://datetime.perl.org>. go click around 🌈

🧚‍♀️💖 okay that’s the whole DateTi...SpanSet(3pm) page, bestie — this one’s from perl v5.42.2, dated 2026-02-15. periodt ✨

📦 where this page comes from

alpine 3.24: perl-datetime-set-doc 0.3900-r1 · GPL-1.0-or-later OR Artistic-1.0-Perl
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on 2026-11-06: a language model's rewrite of the original, under its terms