PSR-12 Extended Coding Style Guide

Indentation and Lines

<?php
// MUST use 4 spaces for indentation (no tabs)
class Product
{
    public function getPrice(): float   // 4 spaces
    {                                  // Opening brace on next line
        return $this->price;           // 8 spaces (4 + 4)
    }
}

// There MUST NOT be a hard limit on line length
// The soft limit SHOULD be 120 characters
// Lines SHOULD NOT be longer than 80 characters

// There MUST be one blank line after namespace declaration
namespace Vendor\Module\Model;

// There MUST be one blank line after the use block
use Magento\Framework\Model\AbstractModel;
use Magento\Catalog\Api\ProductRepositoryInterface;

Namespace and Use Statements

<?php
// Namespace declaration
namespace Vendor\Module\Model;

// One blank line after namespace

// One use keyword per declaration
use Magento\Framework\Model\AbstractModel;
use Magento\Catalog\Api\ProductRepositoryInterface;
use Psr\Log\LoggerInterface;

// One blank line after the use block

class Product extends AbstractModel
{
    // ...
}

Class Spacing

<?php
namespace Vendor\Module\Model;

use Magento\Framework\Model\AbstractModel;

class Product extends AbstractModel
{
    // ONE blank line after class opening brace

    public string $name;
    public float $price;

    // ONE blank line between properties and methods

    public function __construct(
        string $name,
        float $price
    ) {
        $this->name = $name;
        $this->price = $price;
    }

    // ONE blank line between methods

    public function getName(): string
    {
        return $this->name;
    }

    public function getPrice(): float
    {
        return $this->price;
    }
}

Method Spacing

<?php
// Method opening brace on NEXT line
class Product
{
    public function getPrice(): float
    {                          // Brace on its own line
        return $this->price;   // Body indented 4 spaces
    }                          // Closing brace

    // No blank line before closing brace (for single-method classes)
}

// Method arguments with defaults go at end
public function create(
    string $name,
    float $price,
    string $sku = '',           // Default at end
    bool $active = true         // Default at end
): Product {
    // ...
}

Visibility

<?php
class Product
{
    // Visibility MUST be declared on ALL properties
    public string $name;         // public
    protected float $price;      // protected
    private string $sku;         // private

    // Visibility MUST be declared on ALL methods
    public function getName(): string {}
    protected function calculateDiscount(): float {}
    private function validateData(): bool {}

    // abstract and final MUST precede visibility
    abstract public function getType(): string;
    final public function getId(): int {}

    // static MUST follow visibility
    public static function getCount(): int {}
}

Key Takeaway

PSR-12 requires 4 spaces indentation, visibility on all members, methods on next line, one blank line between methods, and proper namespace/use statement formatting.

Control Structures

<?php
// Opening brace on SAME line for control structures
if ($condition) {
    // ...
} elseif ($otherCondition) {
    // ...
} else {
    // ...
}

// switch statement
switch ($value) {
    case 1:
        // ...
        break;
    case 2:
        // ...
        break;
    default:
        // ...
        break;
}

// while, for, foreach
while ($condition) {
    // ...
}

for ($i = 0; $i < 10; $i++) {
    // ...
}

foreach ($items as $key => $value) {
    // ...
}

// try-catch-finally
try {
    // ...
} catch (\Exception $e) {
    // ...
} finally {
    // ...
}

Ternary and Null Coalescing

<?php
// Ternary operator
$value = $condition ? $trueValue : $falseValue;

// Multiline ternary (each part on its own line)
$value = $condition
    ? $trueValue
    : $falseValue;

// Null coalescing
$value = $variable ?? 'default';

// Chained
$value = $a ?? $b ?? $c ?? 'default';

PHP 7+ Features

<?php
// Return type declarations
function getPrice(): float
{
    return $this->price;
}

// Nullable return type
function findProduct(int $id): ?Product
{
    return $this->repository->getById($id);
}

// Scalar type hints
function formatPrice(float $price, string $currency = 'USD'): string
{
    return number_format($price, 2) . ' ' . $currency;
}

// Short array syntax (preferred)
$array = [1, 2, 3];
$assoc = ['key' => 'value'];

// Long array syntax (avoid)
$array = array(1, 2, 3);

PHP 8 Features

<?php
// Constructor promotion
class Product
{
    public function __construct(
        public readonly string $name,
        public readonly float $price,
    ) {}
}

// Named arguments
createUser(
    email: 'user@example.com',
    name: 'John',
    role: 'admin'
);

// Match expression
$result = match($status) {
    200 => 'OK',
    404 => 'Not Found',
    default => 'Unknown',
};

// Union types
function formatId(int|string $id): string
{
    return (string)$id;
}

Key Takeaway

Control structures use opening braces on the same line. Methods use braces on the next line. PHP 7+ features (return types, type hints) are standard. PHP 8 features (match, named args) follow the same style rules.