Learn Advanced PHP and Object-Oriented Application Design
Make boundaries explicit
Separate input parsing, application rules, persistence, and presentation. Use typed method contracts where they clarify expected values, and choose exceptions that communicate failures meaningfully. Keep framework-independent rules small enough to test without booting an entire web request.
Prefer composition and useful abstractions
Interfaces are most useful when they define a boundary that needs substitution or isolation, such as an external payment or notification service. Composition can keep behavior focused without deep inheritance trees. Avoid creating abstractions that simply rename a single method with no meaningful contract.
Use Composer and autoloading deliberately
Organize namespaces around application responsibilities and let Composer resolve classes consistently. Treat dependency updates as reviewed changes: understand compatibility, run tests, and avoid committing credentials or generated vendor files unnecessarily.
Practice task
Refactor a procedural checkout calculation into small, typed PHP components. Add tests for empty input, invalid quantities, and boundary values. Explain which logic is pure and which part requires a database or external service.