PHP Abstract Classes and Methods

Abstract classes and methods are used to define common behavior and structure that must be implemented by concrete (non-abstract) classes.

Abstract classes cannot be instantiated directly and are typically used as base classes to provide a blueprint for derived classes.

Here’s how abstract classes and methods work in PHP:

Abstract Classes:

An abstract class is declared using the abstract keyword.

It can contain a combination of regular methods (with implementations) and abstract methods (without implementations).

Abstract methods are declared using the abstract keyword and do not have a method body.

abstract class Animal {
    protected $name;

    public function __construct($name) {
        $this->name = $name;
    }

    abstract public function makeSound();
}

In the above example, the Animal class is an abstract class that has a constructor and an abstract method called makeSound().

The makeSound() method does not have an implementation in the abstract class, but it must be implemented by any concrete class that extends the Animal class.

Abstract Methods:

Abstract methods declared within an abstract class provide a contract that any derived class must fulfill. Any class that extends an abstract class must implement all the abstract methods defined in the parent abstract class.

class Dog extends Animal {
    public function makeSound() {
        echo "Dog is barking.";
    }
}

In the above example, the Dog class extends the Animal abstract class and provides an implementation for the makeSound() method. This is required because makeSound() is an abstract method defined in the Animal class.

Abstract classes can have regular methods with implementations, and they can also have properties. However, an abstract class cannot be instantiated directly. You must create a derived class that extends the abstract class and implements all the abstract methods.

Abstract classes provide a way to define common behavior and structure while allowing flexibility for derived classes to provide their own implementations. They are particularly useful when you want to enforce certain methods to be implemented in derived classes to ensure consistent behavior across related classes.