Not sure if this is a useful answer, however you seem to be struggling with overriding methods so consider:

# file noname1.pm:
use strict;
use warnings;

package Hello;

sub new {
    my $type = shift; # Call as: Hello->new ();
    my $class = ref $type || $type;
    
    return bless {}, $class;
}


sub hi {
    my ($self, $tail) = @_;
    
    $tail ||= '';
    return 'Hello' . $tail;
}

1;

package World;

use noname1;
use base qw(Hello);

sub new {
    my $type = shift; # Call as: World->new ();
    my $class = ref $type || $type;
    
    return Hello::new ($class);
}


sub hi {
    my ($self, $tail) = @_;
    
    $tail ||= '';

    # Now call up to get base class work done
    return $self->Hello::hi (' World' . $tail);
}

1;


#file noname.pl:
use strict;
use warnings;
use noname1;

my $hi = World->new (); # Create derived class object

print $hi->hi ('. How goes it?'); # Call method on derived class objec
+t
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Prints:

Hello World. How goes it?
[download]