Overview of Inheritance

In OOP, inheritance facilitates code reuse by allowing child classes to extend parent classes. This means that when a class inherits from another, it gains access to all its attributes and methods. This structure enables targeted customization, permitting developers to modify only the necessary code. The action of invoking inherited methods is referred to as calling or invoking super(). Through inheritance, you can create specific objects with tailored features. For instance, if you define a base class called Dog, you can then create specialized classes like GermanShepherdDog, Dalmatian, and Poodle. This method is far more efficient than coding every distinct characteristic for each dog type separately. While each dog maintains its identity, they share common traits due to their inheritance from the base class.

This video, "Inheritance In OOP Explained - And Why You Shouldn't Abuse It," provides an overview of inheritance in OOP and cautions against its misuse.

Understanding Polymorphism

Polymorphism can be described simply as one interface supporting multiple functions. Within the context of inheritance, this means that a subclass can be utilized in place of its superclass. Polymorphism is crucial in programs that manage objects, and it’s beneficial to grasp its principles even if you are not writing object-oriented code. If two objects possess similar appearances and behaviors, they should be interchangeable, regardless of their underlying types. For example, if one structure contains all necessary properties of a superclass and another has most of them, both should function effectively. By allowing classes to inherit from one another without sacrificing functionality, polymorphism enhances flexibility and readability in our programs. This characteristic aligns with the open/closed principle or the Liskov substitution principle, suggesting that your class should function as an open system where new elements can be added, but existing ones remain unchanged. It is also important to recognize that polymorphism can sometimes lead to ambiguity when multiple methods are applicable to a particular message send. Properly defining your interfaces can mitigate these issues.

Abstract Classes Explained

An abstract class functions similarly to an interface but can also have members. It cannot be instantiated, although it may include abstract methods that subclasses can implement. Essentially, an abstract class serves as a blueprint for its descendants, mandating that all derived classes implement its abstract methods and properties. While abstract classes add complexity to your code, they become highly beneficial when paired with polymorphism. A common application might involve creating a base class for UI widgets like buttons and textboxes, which do not inherently model anything. Instead, they serve as containers for other controls. You can then develop specific subclasses, such as ButtonWidget or TextBoxWidget, enabling users to extend these classes and modify behaviors or properties without delving into the implementation details of your library.

Abstract Base Class (ABC)

An abstract base class (ABC) is a template for subclasses that is not derived from any other class. An ABC outlines which members can be inherited and what must be implemented by subclasses, but it does not provide any implementation itself. ABCs are valuable for sharing common information among related classes without requiring multiple inheritance, allowing derived classes to implement only the methods they need. This abstraction helps programmers focus on an object's interfaces rather than its internal structures and algorithms. It also supports future extensions of these interfaces without altering existing code; new types can be derived from a given ABC. For instance, if we establish an abstract base class Shape with pure virtual functions area() and perimeter(), every subclass will be required to implement both functions, ensuring that all classes inheriting from Shape can calculate their area and perimeter.