PHP Inheritance and Polymorphism: Putting it all together to make your code come alive

This article carefully written by PHP editor Apple will deeply explore the concepts of inheritance and polymorphism in PHP, helping readers better understand and apply these two important object-oriented programming concepts. Through integration, the code can be more energetic and spiritual, and the maintainability and scalability of the code can be improved. Inheritance and polymorphism in PHP are the keys to improving code quality and efficiency. I hope this article can bring more gains and inspiration to readers.

Inheritance allows a class to inherit properties and methods from one or more parent classes. Subclasses can inherit the properties and methods of the parent class and extend or rewrite them, thereby achieving code reuse and facilitating the rapid construction of new classes. . In php, use the extends keyword to implement class inheritance:

// 定义父类
class ParentClass
{
protected $name;
protected $age;

public function getName()
{
return $this->name;
}

public function getAge()
{
return $this->age;
}
}

// 定义子类
class ChildClass extends ParentClass
{
protected $gender;

public function getGender()
{
return $this->gender;
}
}

In the above code, ChildClass inherits ParentClass. It not only inherits the properties and methods defined in ParentClass, but also adds gender properties and getGender() method.

Polymorphism is an extension of inheritance that allows subclasses to respond to the same call in different ways, thereby achieving flexibility and decoupling. In PHP, polymorphism is mainly achieved through method rewriting. When a subclass overrides a parent class method, the subclass method will override the parent class method. When a subclass method is called, the subclass overridden method will be executed. method:

// 定义父类
class Animal
{
public function makeSound()
{
return "Animal sound";
}
}

// 定义子类
class Dog extends Animal
{
public function makeSound()
{
return "Woof!";
}
}

// 定义子类
class Cat extends Animal
{
public function makeSound()
{
return "Meow!";
}
}

// 实例化子类
$dog = new Dog();
$cat = new Cat();

// 调用子类的方法
echo $dog->makeSound(); // 输出：Woof!
echo $cat->makeSound(); // 输出：Meow!

In the above code, the Dog class and the Cat class are both subclasses of the Animal class, and they both override makeSound() method, so when $dog->makeSound() and $cat->makeSound() are called, the Dog class will be executed respectively and the makeSound() method defined in the Cat class, not the makeSound() method defined in the Animal class.

Inheritance and polymorphism are important features of PHP object-oriented programming. By rationally applying inheritance and polymorphism, we can build clear and easy-to-maintain code, improve the scalability and flexibility of the code, and thus make developmentThe process is more efficient.

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