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title	PHP Coding Style
scope	php

PHP Coding Style

Standards

Follow PSR-12 and PER Coding Style 2.0 as the baseline. Key rules:

File Structure

Start every PHP file with <?php (no closing tag)
Declare declare(strict_types=1); in every file
One class/interface/trait/enum per file
Follow PSR-4 autoloading: namespace maps to directory structure

Naming

Classes, interfaces, traits, enums: PascalCase
Methods, functions, variables: camelCase
Constants: UPPER_SNAKE_CASE
Namespaces: PascalCase, matching directory structure

Type Declarations

Always declare parameter types, return types, and property types
Use union types (string|int) instead of docblock @param string|int
Use mixed explicitly when the type is truly unknown
Use void return type for methods that return nothing
Prefer readonly properties over getters for value objects
Use constructor promotion for simple DTOs and value objects

Modern PHP (8.1+)

Use enum instead of class constants for fixed sets of values
Use readonly properties for immutable data
Use match instead of switch when returning values
Use named arguments for clarity when calling functions with many parameters
Use first-class callable syntax strlen(...) instead of 'strlen' strings
Use null-safe operator ?-> instead of nested null checks
Use fiber-based async when appropriate

Class Design

Prefer final classes by default — only remove final when extension is explicitly needed
Prefer composition over inheritance
Keep classes small and focused (Single Responsibility)
Use interfaces for contracts, abstract classes only when sharing implementation

Formatting

4 spaces indentation (no tabs)
Opening braces on the same line for control structures
Opening braces on the next line for classes and methods
One blank line between methods
No trailing whitespace
Single blank line at end of file

Tooling

Use PHP-CS-Fixer or Laravel Pint for automated formatting
Configure rules to match PSR-12/PER-CS
Run formatter on save or pre-commit