PHP Access Modifiers

PHP OOP Access Modifiers: A Comprehensive Guide

The concept of access modifiers in Object Oriented Programming (OOP) is fundamental to the development of robust and secure applications. In PHP, access modifiers determine the accessibility of class members and methods, specifying which parts of the code can be accessed and manipulated by other objects or parts of the application. In this article, we will explore the different access modifiers in PHP and how they can be used to control the visibility and accessibility of class members and methods.

PHP Access Modifiers: Overview #

PHP Access Modifiers: Overview

PHP provides three main access modifiers: public, protected, and private. These access modifiers control the visibility and accessibility of class members and methods, dictating who can access and manipulate them. Understanding these access modifiers is essential for developing secure and robust applications.

Public Access Modifier #

Public Access Modifier （公共访问修饰符）

The public access modifier is the most permissive of the three, allowing any object or part of the code to access and manipulate class members and methods marked as public. Public members and methods can be accessed from anywhere within the code, regardless of the location or scope of the accessing object. （公共访问修饰符是三者中最宽松的，允许任何对象或代码的一部分访问和操作标记为公共的类成员和方法。无论访问对象的位置或范围如何，都可以从代码中的任何位置访问公共成员和方法。）

class User {
 public $name;

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

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

Protected Access Modifier #

Protected Access Modifier （受保护的访问修饰符）

The protected access modifier is less permissive than public, but more permissive than private. It allows objects within the same class or any child classes to access and manipulate class members and methods marked as protected. Protected members and methods cannot be accessed from outside the class or any child classes. （受保护的访问修饰符的权限小于公共修饰符，但大于私有修饰符。它允许同一类或任何子类中的对象访问和操作标记为受保护的类成员和方法。无法从类或任何子类外部访问受保护的成员和方法。）

class User {
 protected $email;

 protected function setEmail($email) {
   $this->email = $email;
 }

 protected function getEmail() {
   return $this->email;
 }
}

Private Access Modifier #

Private Access Modifier （隐私访问修饰符）

The private access modifier is the most restrictive of the three, allowing only the object within the same class to access and manipulate class members and methods marked as private. Private members and methods cannot be accessed from outside the class or any child classes. （私有访问修饰符是三者中限制最多的，仅允许同一类中的对象访问和操作标记为私有的类成员和方法。无法从类或任何子类外部访问私有成员和方法。）

class User {
 private $password;

 private function setPassword($password) {
   $this->password = $password;
 }

 private function getPassword() {
   return $this->password;
 }
}

Access Modifiers and Inheritance #

Access Modifiers and Inheritance （访问修饰符和继承）

Inheritance is an important concept in OOP and is used to create new classes that are based on existing classes. When a child class inherits from a parent class, it also inherits the class members and methods of the parent class. However, the access modifiers of the class members and methods of the parent class are also inherited by the child class. （继承是OOP中的一个重要概念，用于创建基于现有类的新类。当子类从父类继承时，它也继承了父类的类成员和方法。但是，父类的类成员和方法的访问修饰符也由子类继承。）

class User {
 protected $email;

 protected function setEmail($email) {
   $this->email = $email;
 }

 protected function getEmail() {
   return $this->email;
 }
}

class Admin extends User {
 public function updateEmail($email) {
   $this->setEmail($email);
 }
}

Conclusion #

Conclusion （结论）

In conclusion, access modifiers in PHP are an essential aspect of OOP and play a crucial role in determining the visibility and accessibility of class members and methods. Understanding how public, protected, and private access modifiers work and how they can be used in inheritance is crucial for the development of secure and robust applications. Using access modifiers, you can control the accessibility of class members and methods, ensuring that sensitive information is kept private and that public members and methods are accessible where needed. By using access modifiers effectively, you can write more organized, maintainable, and secure code.

To summarize, access modifiers are one of the key tools in the OOP toolkit, providing developers with the ability to control the visibility and accessibility of class members and methods. Whether you’re an experienced developer or just starting out, understanding how access modifiers work and how to use them effectively is an important step towards writing clean, maintainable, and secure code. （总而言之，访问修饰符是OOP工具包中的关键工具之一，为开发人员提供了控制类成员和方法的可见性和可访问性的能力。无论您是经验丰富的开发人员还是刚刚起步的开发人员，了解访问修饰符的工作原理以及如何有效地使用它们都是编写干净、可维护和安全代码的重要一步。）