This smells of trying to say something like:

sub baz {
  my $self = shift;
  $self->{smiley} += 25;
  ..
}
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when called as a class method. When you're called as a class method (without an object), the value of $self is no longer a hashref: it's just a string. You'll need to store "class instance" variables instead of "instance" variables. See Damian's excellent book on this.

-- Randal L. Schwartz, Perl hacker