Class::ObjectTemplate::DB extends Class::ObjectTemplate in one
simple way: the undefined() method.

The author finds this useful when representing classes based on
objects stored in databases (hence the name of the module).
That way an object can be created, without triggering a DB lookup.
Later if data is accessed and it is not currently present in the object,
it can be retrieved on an as-need basis.

WWW: https://metacpan.org/release/Class-ObjectTemplate-DB