PHP development specifications and PSR4 namespace specifications

PHP development specifications and PSR-4 namespace specifications

Introduction:
PHP is a widely used programming language. It is important to comply with the specifications during the development process. It is very important, not only to improve the readability and maintainability of the code, but also to improve the efficiency of team collaboration. In this article, we will discuss PHP development specifications and PSR-4 namespace specifications, and provide some specific code examples.

1. PHP development specifications

1. Coding style:

   • Use 4 spaces instead of a tab for indentation;
   • Use a blank line before and after the code structure block;
   • Use camel case naming for variables and functions, and use camel case naming for class names with the first letter capitalized;
   • Use curly brackets Occupies its own line;
   • Use single quotes instead of double quotes to define strings unless parsing variables is required.

Example:

namespace MyApp;

class MyController {
    public function displayMessage($message) {
        echo 'Message: ' . $message;
    }
}

2. Comment specification:

   • Use double slash (//) Make line comments. The comments should be clear and explain the function of the code;
   • Use PHPDoc format to comment on functions, classes and methods;
   • The comment content should include author, date, version and other information .

Example:

/**
 * 收集用户信息
 *
 * @param int $userId 用户ID
 * @param string $username 用户名
 * @return array 用户信息
 */
function collectUserInfo($userId, $username) {
    // ...
}

3. Exception handling:

   • Use try-catch block to handle possible Exception thrown;
   • Throw a specific exception class instead of using the general Exception class.

Example:

try {
    // 可能引发异常的代码
} catch (DatabaseException $e) {
    // 处理数据库异常
} catch (ApiException $e) {
    // 处理API调用异常
} catch (Exception $e) {
    // 处理其他异常
}

2. PSR-4 namespace specification

PSR-4 is the namespace specification recommended by the PHP standard. It defines a standard way for automatic loading of class libraries and applications. According to the PSR-4 specification, the namespace of the class library should be consistent with the file path.

1. Namespace composition:

   • A namespace consists of one or more namespace identifiers, separated by backslashes ();
   • The namespace should be consistent with the physical path of the file. The base directory of the root namespace starts from the project root directory, and other namespaces start from the base directory and continue to add subdirectories.

Example:

project/
  src/
    MyApp/
      Controllers/
        HomeController.php
      Models/
        UserModel.php

The namespace of HomeController.php is: MyAppControllers
The namespace of UserModel.php is: MyAppModels

2. Automatic loading of class libraries:

   • Use the autoload mechanism to load class library files;
   • In composer. Add the autoload field to the json file and specify the psr-4 field;
   • execute the composer dumpautoload command for automatic loading.

Example:

{
    "autoload": {
        "psr-4": {
            "MyApp\": "src/"
        }
    }
}

In this way, the namespace can be used directly in the code to reference the class:

use MyAppControllersHomeController;
use MyAppModelsUserModel;

$homeCtrl = new HomeController();
$userModel = new UserModel();

Summary:
Following PHP development specifications and PSR-4 namespace specifications can improve code quality and maintainability, making team collaboration more efficient. In actual development, we should flexibly apply these specifications according to the needs of the project and the actual situation of the team in order to better develop PHP.

Reference:

• PHP Development Specification (https://www.php-fig.org/psr/psr-12/)
• PSR-4 : Autoloader (https://www.php-fig.org/psr/psr-4/)

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