I am responding to your title, not your questions. If you want a barebones minimal example, drop the export. As JediWizard suggested, use OO, not function exporting. If you want a method, you need an object first.

#!/usr/bin/perl -l
 
package main;
 
for (Dog->new, Cat->new, Cow->new, Foo->new) {
   print "Oh the ", $_->name, " goes ", $_->speak;
}
 
package Animal;
sub new   { bless {}, shift }
sub speak { return "ERROR: did not override" }
sub name  { return ref shift }
 
package Dog;
use base 'Animal';
sub speak { return "Woof" }
 
package Cat;
use base 'Animal';
sub speak { return "Meow" }
 
package Cow;
use base 'Animal';
sub speak { return "Moo" }
 
package Foo;
use base 'Animal';
[download]

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)