Before you trudge all the way down Moose Avenue, give Moo a chance. It’s faster, has fewer deps and, to me, has easier semantics and with the Type::Tiny family, it is super powerful. Note the problem with leap years and the 29th in the implementation I offer.

package Appointment 0.01 {
    use Moo;
    use Types::Standard qw/ Int Enum /;
    use Date::Calc qw/ Today_and_Now check_date /;
    use Carp;

    has month =>
        is => "ro",
        isa => Int,
        required => 1,
        ;

    has day =>
        is => "ro",
        isa => Int,
        required => 1,
        ;

    has freq =>
        is => "ro",
        isa => Enum[qw/ OneTime Daily Monthly Quarterly /],
        default  => sub { "OneTime" }
        ;

    sub BUILD {
        my ( $self, $args ) = @_;
        my @check = ( [ Today_and_Now ]->[0], $self->{month}, $self->{
+day} );
        croak sprintf("Date is invalid for this year: %4d-%02d-%02d", 
+@check)
            unless check_date(@check);
    }
};

1; # <-- Update, return true.
[download]