object-design-skill

What I do

Design objects by responsibility (RDD/CRC), assign stereotypes, honor Tell-Don't-Ask, Design by Contract, composition over inheritance, Law of Demeter, and value objects. House additions below; textbook mechanics assumed known.

When to use me

• Modeling a new domain: finding objects and responsibilities, choosing entity vs value object
• Reviewing object interactions (feature envy, inappropriate intimacy, get-then-act chains)

House Learnings

Learning: primitive-obsession-report-type

Raw String for a type code crossing API/service/domain layers has zero compile-time safety — a typo like "pfd" silently falls through dispatch and lands in the DB. Replace with a str-based Enum value object end-to-end: dispatch via _GENERATORS[report_type], persist report_type.value, and ReportType("pfd") raises at the boundary instead of corrupting data.

Learning: enum-strategy-resolution

An enum can be both a type identifier (value object) AND a strategy dispatcher: each member carries content_type, extension, and serialize(data) via properties backed by module-level _CONTENT_TYPES/_SERIALIZERS maps — eliminating external mapping tables and switch dispatch.

Removed 2026-09: RDD/CRC walkthroughs, stereotype catalog, DbC pre/post-condition examples, composition-vs-inheritance and Law-of-Demeter explanations, encapsulation levels, entity-vs-value-object tutorials — textbook the model knows; the two codified learnings are this config's additions.