Don't hardcode the daughterclass names, or else you won't be able to subclass the factory class. Instead, call a method that returns the daughterclass name:

sub TypeA { return "Class::SubclassA" }
sub TypeB { return "Class::SubclassB" }
sub create {
  my $class = shift;
  if (shift eq "B") {
    return $class->TypeB->new(@_);
  } else {
    return $class->TypeA->new(@_);
  }
}
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