Paraphrased from the Data:Swap's documentation  ...

Data::Swap (XS) module allows to swap the contents of two referenced
variables, even if they have different types.  The main application is
to change the base type of an object after it has been created, for
example for dynamic loading of data structures:

      swap $self, bless $replacement, $newclass;

WWW: http://search.cpan.org/dist/Data-Swap/