PSR represents the PHP standard recommendation in PHP, and is proposed by the PHP Framework Interoperability Group (PHP-FIG), which is used to unify code style, improve readability and collaboration efficiency. Its core goal is to promote compatibility between different frameworks and libraries, although not mandatory, but widely adopted. Common PSR standards include: 1. PSR-1: basic encoding specification, which stipulates the use of <?php tags, one class per file, StudlyCaps for class names, camelCase for method names, etc.; 2. PSR-4: automatic loading standard, which defines the automatic loading method of class based on namespace and directory structure, and is used by most modern frameworks and Composers; 3. PSR-12: extends the code style specification, adds more detailed format rules based on PSR-1, such as spaces around operators, line breaks after controlling structures, etc. Developers follow PSR standards to improve code consistency, facilitate collaboration, obtain tool support and enhance framework compatibility. Application methods include: using PHP_CodeSniffer to check code, configuring IDE to automatically format, automatically fix format problems through PHP-CS-Fixer, and installing related development dependencies in Composer projects. Mastering PSR-1, PSR-4 and PSR-12 is particularly important for PHP developers, and can significantly improve development efficiency and code quality.

PSR stands for PHP Standards Recommendations. These are coding standards, style guides, and best practices proposed by the PHP Framework Interop Group (PHP-FIG), which is a group formed by several major PHP projects to promote interoperability between different frameworks and libraries.

The goal of PSR standards is to make PHP code more consistent and reusable across different projects. While they're not mandatory, many PHP frameworks and open-source projects adopt them to ensure clean, readable, and maintainable code.

Commonly Adopted PSR Standards in PHP

There are several PSR standards, but some are more widely adopted than others:

• PSR-1: Basic Coding Standard
  This is the foundation. It defines basic rules like using <?php tags, having one class per file, following StudlyCaps for class names, camelCase for method names, etc.

• PSR-4: Autoloading Standard
  Probably the most widely used. It defines how classes should be autoloaded based on their namespace and directory structure. Most modern PHP frameworks and Composer rely on PSR-4 autoloading.

  

• PSR-12: Extended Coding Style
  Also known as "PSR-12 Extended," it builds upon PSR-1 and adds more detailed formatting rules, such as spacing around operators, line breaks after control structures, and more.

Other PSRs like PSR-3 (logging interface), PSR-7 (HTTP message interfaces), and PSR-11 (container interface) are also used, especially in larger applications or when integrating with third-party tools.

Why Developers Follow PSR Standards

Following PSR standards helps developers in several ways:

• Improved Readability: Code looks familiar even when switching between projects.
• Easier Collaboration: Team members can quickly understand each other's code.
• Tooling Support: Tools like PHP-CS-Fixer, PHP_CodeSniffer, and IDEs support PSR out of the box.
• Framework Compatibility: Most modern PHP frameworks (like Laravel, Symfony, Zend) follow PSR standards, making integration smoother.

Using these standards doesn't mean you have to write code exactly the same way every time, but it gives you a solid baseline that's widely accepted.

How to Apply PSR Standards in Your Project

If you're starting a new project or cleaning up an old one, here are a few steps you can take:

• Use a linter or code sniffer tool like PHP_CodeSniffer to check your code against PSR standards.
• Configure your editor or IDE to format code according to PSR-12 automatically.
• Set up automatic fixes using PHP-CS-Fixer in your development workflow or CI pipeline.
• If you're building a library, consider following PSR-4 for autoloading and PSR-12 for code style.

Composer makes it easy to install these tools via composer require --dev . Once set up, running them becomes part of your regular development routine.

So if you're working with PHP seriously, especially in teams or open-source projects, getting comfortable with PSR standards—especially PSR-1, PSR-4, and PSR-12—is definitely worth your time. It's not hard to follow once you get used to it, and the benefits show up quickly in terms of code quality and collaboration ease.

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