Re^2: Check if Date interval contains Hour X

[ikegami]

I thought you were on to something until I realized the real problem is finding the right date to go with the hour. Using ::Span makes things a lot more complicated since you now need to make 4 DateTime objects for every hour.

[alexm]

The very first thing that came to my mind after reading the OP was the method DateTime::Span::contains. However, yours is the right approach since that method only works for sets that are fully inside, as the manual says.

Thanks!

[ikegami]

contains wouldn't work, but intersects would

...| 20 | 21 | 22 | 23 | 00 | 01 | 02 | 03 |...
                  (------------)     log
                            (----]   hour
                            (--)     intersection

[alexm]

You're right again, I just realized a bit later so I've been playing with intersects:

sub hour_in_range {
    my ($dt_s, $dt_e, @hours) = @_;

    my $dt_span = DateTime::Span->from_datetimes(
        start => $dt_s, end => $dt_e
    );

    for my $hour (@hours) {
        my $dt = $dt_s->clone()
                      ->truncate( to => 'day' )
                      ->add( hours => $hour );

        $dt->add( days => 1 ) if $dt < $dt_s;

        my $hour_span = DateTime::Span->from_datetimes(
            start => $dt, end => $dt
        );

        return 1 if $dt_span->intersects($hour_span);
    }

    return 0;
}

It's not as simple and efficient as your approach, but it shows how to use span intersection.

OTOH, I misunderstood the OP and was thinking that @hours = (1,11) was an interval (1am to 11am), not a list of hours to match.