PHP-FIG matters because it created shared standards for PHP frameworks. Before PHP-FIG, frameworks used different methods for tasks like autoloading and HTTP handling, making code reuse difficult. The group introduced PSRs like 1. PSR-1 (coding style basics), 2. PSR-4 (autoloading standard for namespaces), and 3. PSR-7 (HTTP message interfaces), enabling cross-framework compatibility. Other key standards include PSR-12 (extended style), PSR-3 (logging), and PSR-11 (container interface). Developers can adopt these standards using Composer for autoloading, tools like PHP_CodeSniffer for code style enforcement, and by building reusable packages with PSR-7 or PSR-11 support. Following major PSRs improves interoperability and reduces development complexity.

PHP-FIG stands for the PHP Framework Interop Group, and it's basically a group of PHP framework representatives who got together to talk about common standards. The goal was simple: make it easier for different PHP frameworks and libraries to work together.

Why PHP-FIG Matters

Before PHP-FIG, each PHP framework had its own way of doing things — from autoloading classes to handling HTTP requests. This made it hard for developers to switch between frameworks or reuse code across projects. PHP-FIG aimed to fix that by creating shared standards.

The cool part? These aren't official PHP rules — they're just recommendations. But over time, most major PHP projects and frameworks (like Laravel, Symfony, and Composer) adopted them. That makes life a lot easier if you're building with PHP today.

The Big Standards You Should Know

Here are some of the main standards (called PSRs — PHP Standard Recommendations) that came out of PHP-FIG:

PSR-1: Basic Coding Standard

This is like the ground floor of good PHP style. It covers basic stuff like:

• Class names should be in StudlyCaps
• Method and variable names can be in camelCase
• PHP files should only contain PHP code (no HTML or other stuff at the start or end)

It’s not super detailed, but it sets a baseline so everyone’s on the same page when reading code.

PSR-4: Autoloading Standard

This one’s huge. Before PSR-4, every framework had its own way of auto-loading classes. Now, most use PSR-4.

What does it do?
It says how class files should be named and where they should live based on their namespace. So if you have a class called App\Utils\Logger, PSR-4 tells you to look for it in a file like src/Utils/Logger.php under the App directory.

Composer uses this by default, which makes including third-party packages much smoother.

PSR-7: HTTP Message Interfaces

This standard defines interfaces for HTTP messages — things like requests and responses. It means libraries can work with any framework that supports PSR-7, instead of being locked into one.

So if you build a middleware that works with PSR-7, it can plug into Slim, Lumen, or any other compatible framework.

Other important ones include:

• PSR-12 – Extended coding style (builds on PSR-1)
• PSR-3 – Logging interface
• PSR-11 – Container interface

They’re not all required, but the more your project follows them, the easier it’ll play with others.

How to Use These Standards in Real Life

If you're using a modern PHP framework, chances are you're already following most of these without thinking about it. Here’s how to take advantage more intentionally:

• Use Composer – It supports PSR-4 autoloading out of the box. Just define your namespaces and directories in composer.json.
• Check your code style – Tools like PHP_CodeSniffer or PHP-CS-Fixer can help enforce PSR-1 or PSR-12.
• Build reusable packages – If you want your library to work across frameworks, implement PSR-7 or PSR-11 where applicable.

You don’t have to follow every PSR, but sticking to the big ones will save headaches down the line.

That’s the gist of PHP-FIG and its standards — basically a set of agreements that make PHP projects more compatible and easier to work with. Not magic, just practical collaboration.

The above is the detailed content of What is PHP-FIG and what are its standards?. For more information, please follow other related articles on the PHP Chinese website!