Examing cotets of NEW & OLD in a function programed in perl

I need to write a generic function to process data before allowing the
insert or update to continue.

To do this, I need to be able to examine the NEW, and OLD structures
without prior knowledge of the structure of the table that fired the
trigger.

Can someone show me an example of how to get these structures into
something I can work with in Perl?


-- 
"They that would give up essential liberty for temporary safety deserve
neither liberty nor safety."
                        -- Benjamin Franklin