Sharing of project practical experience of PSR2 and PSR4 specifications

Sharing of project practical experience of PSR2 and PSR4 specifications

Preface

In modern software development, it is very important to follow unified coding standards. It improves code readability and maintainability and reduces friction in teamwork. PHP-FIG (PHP Framework Interop Group) has developed a series of PSR specifications, the most well-known of which are PSR2 and PSR4. This article will share some experiences in following PSR2 and PSR4 specifications in project practice and provide some specific code examples.

PSR2 specification

The PSR2 specification mainly focuses on the uniformity of code style and formatting. Here are some recommendations from the PSR2 specification that we follow in our projects:

1. Code Indentation: Use 4 spaces for level indentation instead of tabs.

   // 错误的示例
   function helloWorld()
   {
   ∙∙echo "Hello World!";
   }
   
   // 正确的示例
   function helloWorld()
   {
   ∙∙∙∙echo "Hello World!";
   }

2. Line width limit: The width of each line of code should not exceed 80 characters.

   // 错误的示例
   function longMethodNameWithTooManyParametersAndALongReturnStatement(
   ∙∙$parameter1, $parameter2, $parameter3, $parameter4, $parameter5
   )
   {
   ∙∙∙∙//...
   }
   
   // 正确的示例
   function longMethodNameWithTooManyParametersAndALongReturnStatement(
   ∙∙$parameter1,
   ∙∙$parameter2,
   ∙∙$parameter3,
   ∙∙$parameter4,
   ∙∙$parameter5
   )
   {
   ∙∙∙∙//...
   }

3. Blank line: Use a blank line to separate between methods of a class and between logical blocks of methods.

   // 错误的示例
   class MyClass
   {
   ∙∙public function method1()
   ∙∙{
   ∙∙∙∙//...
   ∙∙}
   ∙∙public function method2()
   ∙∙{
   ∙∙∙∙//...
   ∙∙}
   }
   
   // 正确的示例
   class MyClass
   {
   ∙∙public function method1()
   ∙∙{
   ∙∙∙∙//...
   ∙∙}
   
   ∙∙public function method2()
   ∙∙{
   ∙∙∙∙//...
   ∙∙}
   }

PSR4 specification
PSR4 specification mainly focuses on the implementation of automatic loading. The following are some experiences of the PSR4 specification that we follow in the project:

1. Namespace and class name: Each class corresponds to an independent file, the file name and class name are consistent, and use Namespaces are organized.

   // 文件路径：src/MyNamespace/MyClass.php
   namespace MyNamespace;
   
   class MyClass
   {
   ∙∙//...
   }

2. Auto-loading: Use Composer to manage dependencies and use its auto-loading feature in your project.

   // composer.json
   {
   ∙∙"autoload": {
   ∙∙∙∙"psr-4": {
   ∙∙∙∙∙∙"MyNamespace\": "src/"
   ∙∙∙∙}
   ∙∙}
   }

3. Directory structure: The directory structure that follows the PSR4 specification can improve the organization and maintainability of the code.

   // 错误的示例
   src/
   ∙∙MyClass.php
   ∙∙MyOtherClass.php
   
   // 正确的示例
   src/
   ∙∙MyNamespace/
   ∙∙∙∙MyClass.php
   ∙∙∙∙MyOtherClass.php

Conclusion

Following the PSR2 and PSR4 specifications can make your code more consistent and readable, and improve team collaboration efficiency. This article describes some of our experiences following these specifications in projects and provides some concrete code examples. Of course, specifications are only the basis. We should also flexibly apply these specifications according to the needs of actual projects in order to pursue better code quality and development efficiency. I hope these experiences will be helpful to you in your projects using PSR2 and PSR4 specifications.

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