Class::MethodMaker. Included is a Class::MethodMaker v1 emulator that
provides better compatibility than the one in Class::MethodMaker v2.
From DESCR:
By passing arguments to "use Class::MakeMethods ..." statements, you can
select from a library of hundreds of common types of methods, which are
dynamically installed as subroutines in your module, simplifying the
code for your class.