The terms “super” and “extends” play crucial roles in object-oriented programming (OOP), particularly in languages like Java and Python. While they serve different purposes and are implemented differently across languages, they both contribute to code reusability and maintainability through inheritance.

‘super’ Keyword: Accessing Parent Class Functionality

The ‘super’ keyword allows a subclass (child class) to access members (methods and properties) of its parent class (superclass). This is particularly useful when a subclass overrides a method of the superclass but still needs to call the original implementation. The specific syntax and usage of ‘super’ vary between languages.

“When you put an Object to the List, all you care about is that the object is of a type that is compatible with type held by the list.”

In Python, ‘super’ is used to call a method from a parent class. It simplifies the process of initializing parent class attributes and calling parent class methods within a subclass. However, using ‘super’ in Python 2 can be tricky, especially when dealing with multiple inheritance and argument passing [2], [3]. Python 3 simplifies this process.

‘extends’ Keyword: Implementing Inheritance

The ‘extends’ keyword, commonly found in languages like Java, is used to establish an inheritance relationship between two classes. When a class ‘extends’ another class, it inherits all the non-private members (methods and properties) of the parent class.This allows the subclass to reuse the code of the superclass and add its own specific functionality.

In java generics, ‘extends’ is also used to define upper bounds for type parameters. For example, List<? extends Number> means that the list can hold objects of type Number or any of its subclasses (e.g., Integer, Double). The super keyword in Java generics defines a lower bound.List<? super Suit> indicates the list can except objects of type Suit or any of its superclasses [1]. This is useful when writing to a list, ensuring type compatibility.