Because there isn't just one SUPER: perl needs to know what class you want the superclass of. If you tell it, perl will be happy:

  $foo1->bang();
  $foo2->bang();
  { package BAZ; $foo3->SUPER::bang(); }
[download]

This is needed because you may have another class:

  package QUUX;
  use base qw/ BAR /;
  sub bang { shift->SUPER::bang }
[download]

.. which means that BAR::bang() may be called by objects that don't have ref($self) eq 'BAR'.

Hugo