Home Backend Development PHP Tutorial php namespace (detailed answer combined with code)

php namespace (detailed answer combined with code)

May 17, 2018 pm 02:37 PM
php space

In php## namespace, you need to know the terminology of the three names of spaces: unqualified names, qualified names, fully qualified names, and how PHP parses them. The official documents are very good, so I just used them. Understanding them is very helpful for learning the following content. We learned earlier about the subspace and public space of the namespace. It makes sense that the calling syntax of the namespace is like a file path. It allows us to customize the subspace to describe the relationship between each space.

The terms for the three names in the namespace are as follows:

1. Unqualified name, or class name that does not include a prefix, such as $comment = new Comment();. If the current namespace is Blog\Article, Comment will be parsed as Blog\Article\Comment. If the code using Comment does not contain code in any namespace (in the global space), the Comment will be parsed as a Comment.

2. Qualified name, or name containing prefix, such as $comment = new Article\Comment();. If the current namespace is Blog, Comment will be parsed as Blog\Article\Comment. If the code using Comment does not contain code in any namespace (in the global space), the Comment will be parsed as a Comment.

3. Fully qualified name, or a name that includes the global prefix

operator, such as $comment = new \Article\Comment();. In this case, Comment is always resolved to the literal name Article\Comment in the code.

In fact, these three names can be compared to file names (such as comment.php), relative path names (such as ./article/comment.php), and absolute path names (such as /blog/article/comment. php) which might be easier to understand.

Create a Blog space here, using an unqualified name to represent the current Blog space. This call will be parsed after instantiation. Use a qualified name to indicate that it is relative to the Blog space. After instantiation, this call will be parsed into Blog\Article\Comment(). Note that there is no backslash in front of the class. Use a fully qualified name, indicating that it is absolute to the Blog space. This call will be parsed after instantiation. Note the difference between a backslash in front of the class and no backslash.

The sample code is as follows:

[html] view plain copy
<?php  
//创建空间Blog  
namespace Blog;  
class Comment { }  
//非限定名称,表示当前Blog空间  
//这个调用将被解析成 Blog\Comment();  
$blog_comment = new Comment();  
//限定名称,表示相对于Blog空间  
//这个调用将被解析成 Blog\Article\Comment();  
$article_comment = new Article\Comment(); //类前面没有反斜杆\  
//完全限定名称,表示绝对于Blog空间  
//这个调用将被解析成 Blog\Comment();  
$article_comment = new \Blog\Comment(); //类前面有反斜杆\  
//完全限定名称,表示绝对于Blog空间  
//这个调用将被解析成 Blog\Article\Comment();  
$article_comment = new \Blog\Article\Comment(); //类前面有反斜杆\  
//创建Blog的子空间Article  
namespace Blog\Article;  
class Comment { }  
?>
Copy after login

The above is the php namespace I compiled for everyone. I hope it will be helpful to everyone in the future.

Related articles:

Detailed introduction to the difference between PHP namespace and automatic loading

Detailed introduction to PHP in combination with code Scope

Detailed usage method in PHP closure function() use()

The above is the detailed content of php namespace (detailed answer combined with code). For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Hot Topics

Java Tutorial
1664
14
PHP Tutorial
1266
29
C# Tutorial
1239
24
Explain JSON Web Tokens (JWT) and their use case in PHP APIs. Explain JSON Web Tokens (JWT) and their use case in PHP APIs. Apr 05, 2025 am 12:04 AM

JWT is an open standard based on JSON, used to securely transmit information between parties, mainly for identity authentication and information exchange. 1. JWT consists of three parts: Header, Payload and Signature. 2. The working principle of JWT includes three steps: generating JWT, verifying JWT and parsing Payload. 3. When using JWT for authentication in PHP, JWT can be generated and verified, and user role and permission information can be included in advanced usage. 4. Common errors include signature verification failure, token expiration, and payload oversized. Debugging skills include using debugging tools and logging. 5. Performance optimization and best practices include using appropriate signature algorithms, setting validity periods reasonably,

Explain late static binding in PHP (static::). Explain late static binding in PHP (static::). Apr 03, 2025 am 12:04 AM

Static binding (static::) implements late static binding (LSB) in PHP, allowing calling classes to be referenced in static contexts rather than defining classes. 1) The parsing process is performed at runtime, 2) Look up the call class in the inheritance relationship, 3) It may bring performance overhead.

PHP Program to Count Vowels in a String PHP Program to Count Vowels in a String Feb 07, 2025 pm 12:12 PM

A string is a sequence of characters, including letters, numbers, and symbols. This tutorial will learn how to calculate the number of vowels in a given string in PHP using different methods. The vowels in English are a, e, i, o, u, and they can be uppercase or lowercase. What is a vowel? Vowels are alphabetic characters that represent a specific pronunciation. There are five vowels in English, including uppercase and lowercase: a, e, i, o, u Example 1 Input: String = "Tutorialspoint" Output: 6 explain The vowels in the string "Tutorialspoint" are u, o, i, a, o, i. There are 6 yuan in total

What are PHP magic methods (__construct, __destruct, __call, __get, __set, etc.) and provide use cases? What are PHP magic methods (__construct, __destruct, __call, __get, __set, etc.) and provide use cases? Apr 03, 2025 am 12:03 AM

What are the magic methods of PHP? PHP's magic methods include: 1.\_\_construct, used to initialize objects; 2.\_\_destruct, used to clean up resources; 3.\_\_call, handle non-existent method calls; 4.\_\_get, implement dynamic attribute access; 5.\_\_set, implement dynamic attribute settings. These methods are automatically called in certain situations, improving code flexibility and efficiency.

PHP and Python: Comparing Two Popular Programming Languages PHP and Python: Comparing Two Popular Programming Languages Apr 14, 2025 am 12:13 AM

PHP and Python each have their own advantages, and choose according to project requirements. 1.PHP is suitable for web development, especially for rapid development and maintenance of websites. 2. Python is suitable for data science, machine learning and artificial intelligence, with concise syntax and suitable for beginners.

PHP in Action: Real-World Examples and Applications PHP in Action: Real-World Examples and Applications Apr 14, 2025 am 12:19 AM

PHP is widely used in e-commerce, content management systems and API development. 1) E-commerce: used for shopping cart function and payment processing. 2) Content management system: used for dynamic content generation and user management. 3) API development: used for RESTful API development and API security. Through performance optimization and best practices, the efficiency and maintainability of PHP applications are improved.

PHP: A Key Language for Web Development PHP: A Key Language for Web Development Apr 13, 2025 am 12:08 AM

PHP is a scripting language widely used on the server side, especially suitable for web development. 1.PHP can embed HTML, process HTTP requests and responses, and supports a variety of databases. 2.PHP is used to generate dynamic web content, process form data, access databases, etc., with strong community support and open source resources. 3. PHP is an interpreted language, and the execution process includes lexical analysis, grammatical analysis, compilation and execution. 4.PHP can be combined with MySQL for advanced applications such as user registration systems. 5. When debugging PHP, you can use functions such as error_reporting() and var_dump(). 6. Optimize PHP code to use caching mechanisms, optimize database queries and use built-in functions. 7

Explain the match expression (PHP 8 ) and how it differs from switch. Explain the match expression (PHP 8 ) and how it differs from switch. Apr 06, 2025 am 12:03 AM

In PHP8, match expressions are a new control structure that returns different results based on the value of the expression. 1) It is similar to a switch statement, but returns a value instead of an execution statement block. 2) The match expression is strictly compared (===), which improves security. 3) It avoids possible break omissions in switch statements and enhances the simplicity and readability of the code.

See all articles