Polymorphism in Dart Overview#

Polymorphism allows objects to take on many forms, enabling flexible and reusable code. Dart supports polymorphism through inheritance, interfaces, and method overriding, with both compile-time and runtime variations.

Key Concepts#

1. Compile-time vs Runtime Polymorphism#

• Method overloading (compile-time)
• Method overriding (runtime)
• Static vs dynamic dispatch
• Dart’s approach

2. Interface-based Polymorphism#

• Implicit interfaces
• Multiple interface implementation
• implements keyword
• Abstract classes as interfaces

3. Overriding and Dynamic Dispatch#

• @override annotation
• Virtual method table
• Runtime type checking
• Performance considerations

4. Covariant and Contravariant Types#

• Return type covariance
• Parameter contravariance
• Type safety rules
• Dart 2.x type system