Library: Half-open Enumeration pattern

[stijn-dejongh]

Outline

Combine the type safety and determinism of enumerations with the runtype/deploy time extensibility offered by configuration files. A half-open enumeration type will first look through it's predefined (in-code) specifications, and add a new type object in case the requested type is not available.

Usage desiderata

Should read similarly to the Optional class in java enumFor(String name).orElse(EnumClass::create).

Implementation Notes

• This is basically a constrained Factory Class pattern on top of predefined enumerations.
• There should be an option to configure the factory to only allow the creation of new Type-objects if they adhere to certain conditions ( e.g. "exist in database", "are listed in config file", "contain certain words" )