PHP Abstract Classes

What is an Abstract Class?

An abstract class in PHP is a class that cannot be instantiated on its own. It is designed to be a base class for other classes. Abstract classes are useful when you want to provide a common interface for different subclasses, while allowing each subclass to implement its own version of the methods. In PHP, abstract classes are defined using the abstract keyword.

Defining an Abstract Class

To define an abstract class in PHP, use the abstract keyword before the class declaration. Abstract classes can include both abstract methods (methods without a body) and concrete methods (methods with a body). Here's an example:

Implementing Abstract Methods

When a class inherits from an abstract class, it must implement all of the abstract methods defined in the parent class. Failing to do so will result in a fatal error. Implementing an abstract method involves defining the method with the same signature in the child class. Here's how you can implement the startEngine method in a subclass:

Using Abstract Classes

Once an abstract class has been extended by a subclass and the abstract methods have been implemented, you can create instances of the subclass and use its methods:

Benefits of Using Abstract Classes

Abstract classes provide a way to enforce a certain structure on subclasses, ensuring they implement specific methods. This can lead to more organized and maintainable code, especially in large projects with multiple developers. Abstract classes also allow you to provide some default functionality, which can be shared among subclasses.

Abstract Classes vs. Interfaces

While both abstract classes and interfaces can be used to define a blueprint for other classes, there are some differences. Abstract classes can include concrete methods with implementation, whereas interfaces can only contain method signatures. Additionally, a class in PHP can inherit from only one abstract class, but it can implement multiple interfaces, allowing for more flexibility in multiple inheritance scenarios.