What Is and Is Not a Package

A good p4o package is a small, cohesive, reusable unit with:

• a clear API
• no app-specific assumptions

A package should have

• High cohesion: one clear purpose
• Low coupling: minimal knowledge of host app internals
• Stable API surface: documented and versioned
• Deterministic behavior: predictable inputs/outputs and test coverage
• Portability: usable by multiple projects without modifications

Good candidates

• Shared utilities: parsing, formatting, validation
• Integration clients with stable contracts
• Cross-cutting primitives: logging, caching, retry/backoff

Not good candidates

• App-specific routing/page logic
• Code tightly bound to one environment or one product
• Thin wrappers with no additional value
• Hidden mutable singletons with implicit side effects