When structuring classes in PHP, what are the advantages and disadvantages of using abstract classes to enforce method implementations compared to interfaces?

Abstract classes in PHP can enforce method implementations by providing default implementations for some methods while requiring subclasses to implement others. This can be useful when you want to provide a common base for a group of classes, but still allow for customization in certain areas. On the other hand, interfaces in PHP can only define method signatures without providing any implementation, which can be more flexible as a class can implement multiple interfaces. Choosing between abstract classes and interfaces depends on the specific requirements of your project.

<?php

// Abstract class example
abstract class Animal {
    abstract public function makeSound();
    
    public function eat() {
        echo "Animal is eating.";
    }
}

class Dog extends Animal {
    public function makeSound() {
        echo "Woof!";
    }
}

// Interface example
interface Shape {
    public function calculateArea();
    public function calculatePerimeter();
}

class Circle implements Shape {
    public function calculateArea() {
        // Calculate area of circle
    }
    
    public function calculatePerimeter() {
        // Calculate perimeter of circle
    }
}