package Foo;

# must use '\' to create the reference, and since it's a 
# reference not an invocation, we can't specify arguments 
# here. (see the .pl file at the end)

*do_something = \&make_do_something;

sub make_do_something {
    # make_do_something is the method called, hence the 
    # object reference will be on *this* @_, not the 
    # one below.
    my ($self, $name) = @_;

##</code><code>##

    return sub {
        if ( $name ne 'foo' ) {
            print "Not foo\n";
            $self->SUPER::do_something();
        }
        print "Foo $name!!!\n";
        return 1;
    }
}
1;


#File: Bar.pm

package Bar;
use base 'Foo';

*do_something = \&Foo::make_do_something;

sub new {
    bless {}, shift();
}

1;


#!/usr/local/bin/perl
use lib '.';
use Foo;
use Bar;

$b = new Bar();
# just calling do_something won't cause the subroutine 
# returned to execute; we've got to do that ourselves.

my $sub = $b->do_something('foo'); # supply args here, not above. store the subroutine ref
$sub->(); # dereference it to run it