Category: OOP

Depend on abstractions (interfaces), not concrete low-level classes.

Use design patterns as reusable solutions to common software design problems.

Centralize object creation with factory classes or factory methods.

Understand Singleton and why modern apps often prefer DI containers instead.

Isolate data access behind repository classes for cleaner domain code.

Separate Model, View, and Controller responsibilities in an OOP app.

Give each class one reason to change — one responsibility.

Make code open for extension but closed for modification.

Ensure subclasses can replace parent types without breaking callers.

Organize classes into namespaces to avoid name collisions.