'Struct::Dumb' creates record-like structure types, similar to the 'struct'
keyword in C, C++ or C#, or 'Record' in Pascal. An invocation of this
module will create a construction function which returns new object
references with the given field values. These references all respond to
lvalue methods that access or modify the values stored.

It's specifically and intentionally not meant to be an object class. You
cannot subclass it. You cannot provide additional methods. You cannot apply
roles or mixins or metaclasses or traits or antlers or whatever else is in
fashion this week.

On the other hand, it is tiny, creates cheap lightweight array-backed
structures, uses nothing outside of core. It's intended simply to be a
slightly nicer way to store data structures, where otherwise you might be
tempted to abuse a hash, complete with the risk of typoing key names. The
constructor will 'croak' if passed the wrong number of arguments, as will
attempts to refer to fields that don't exist.