Problem Statement
Explain the principle of widget composition in Flutter and why it's preferred over inheritance.
Explanation
Widget composition means building complex widgets by combining simpler widgets together rather than using inheritance to add functionality. Flutter's entire UI framework is built on this principle - even complex widgets like Scaffold or Card are compositions of simpler widgets like Container, Padding, Material, and others internally. This approach makes Flutter more flexible and maintainable.
Composition is preferred over inheritance because it's more flexible, avoiding deep inheritance hierarchies that are hard to understand and maintain. You can mix and match widgets in any combination to create custom UIs without being constrained by an inheritance structure. Flutter's widgets are designed as building blocks that work together through composition rather than complex inheritance relationships.
For example, instead of creating a CustomButton that extends Button and overrides styling, you compose existing widgets: Container with decoration for appearance, GestureDetector for tap handling, and Text for label. This approach is more flexible because you can easily modify any part of the composition, reuse pieces in other contexts, and avoid the fragile base class problem.
When building custom widgets, create StatelessWidget or StatefulWidget classes that compose existing widgets in their build methods. Extract reusable widget combinations into separate widget classes rather than using helper methods, as separate widget classes enable Flutter's optimization mechanisms. This composition-first approach makes Flutter code more modular, testable, and maintainable.
