package UserDomain::Person;

package Person;

use warnings;
use UserDomain::Benutzer;

$someone = UserDomain::Benutzer->new("ez", "eins", "zwei", "0", "de", "0");
print $someone;

package UserDomain::Person;

use strict;

sub new {
        my $class = shift;
        my $self = bless {} , ref $class || $class;
        my ($id, $nachname, $vorname, $telnr, $sprache, $aktiv) = @_;

        $self->{'id'} = $id;
        $self->{'nachname'} = $nachname;
        $self->{'vorname'} = $vorname;
        $self->{'telnr'} = $telnr;
        $self->{'sprache'} = $sprache;
        $self->{'aktiv'} = $aktiv;

        # my $self = bless {}, ref $proto || $proto;
        #bless $self, ref $class || $class; # wegen Vererbung
        return $self;
}

package UserDomain::Benutzer;

our @ISA = qw(UserDomain::Person);
use UserDomain::Person;

#use NET::ldap;
use strict;

sub new {
        my $class = shift;
        my ($id, $nachname, $vorname, $telnr, $sprache, $aktiv) = @_;
        $class->SUPER::new($id, $nachname, $vorname, $telnr, $sprache, $aktiv);
        $class->{'letzterLogin'} = "";
        $class->{'berechtigung'} = 0;
}

Can't use string ("UserDomain::Benutzer") as a HASH ref while "strict refs" in use at [...]UserDomain/Benutzer.pm line 13.

sub new {
        my $class = shift;
        my ($id, $nachname, $vorname, $telnr, $sprache, $aktiv) = @_;
        my $self = $class->SUPER::new($id, $nachname, $vorname, $telnr, $sprache, $aktiv);
        $self->{'letzterLogin'} = "";
        $self->{'berechtigung'} = 0;
        return $self;
}