PHP 8 Compatibility Guide¶
Making XOOPS modules compatible with PHP 8.x and leveraging modern features.
PHP Version Timeline¶
timeline
title PHP Version Support
2020 : PHP 8.0 Released
: Named Arguments
: Attributes
: Union Types
2021 : PHP 8.1 Released
: Enums
: Readonly Properties
: Fibers
2022 : PHP 8.2 Released
: Readonly Classes
: Null/False Types
: Deprecation Notices
2023 : PHP 8.3 Released
: Typed Class Constants
: json_validate()
2024 : PHP 8.4 Released
: Property Hooks
: Asymmetric VisibilityBreaking Changes¶
Deprecated/Removed Functions¶
// ❌ REMOVED in PHP 8.0
create_function('$a', 'return $a * 2'); // Use closures
each($array); // Use foreach
$string{0}; // Use $string[0]
// ❌ DEPRECATED in PHP 8.1
strftime('%Y-%m-%d', $timestamp); // Use date() or IntlDateFormatter
$GLOBALS assignment
// ❌ DEPRECATED in PHP 8.2
${$varName}; // Use $$varName or arrays
utf8_encode() / utf8_decode(); // Use mb_convert_encoding()
Type System Changes¶
// ❌ PHP 8.0+ enforces type declarations
function process(int $id) {
// Passing string "123" now throws TypeError in strict mode
}
// ✅ Handle with explicit casting
function process(int $id) {
$id = (int) $id;
}
// ❌ Return type must match
function getData(): array {
return null; // TypeError in PHP 8
}
// ✅ Use nullable return type
function getData(): ?array {
return null; // OK
}
Modern PHP Features for XOOPS¶
Named Arguments (PHP 8.0+)¶
// Before: positional arguments
$form->addElement(new XoopsFormText(
'Title', // caption
'title', // name
50, // size
255, // maxlength
'' // value
), true); // required
// After: named arguments (clearer)
$form->addElement(
element: new XoopsFormText(
caption: 'Title',
name: 'title',
size: 50,
maxlength: 255,
value: ''
),
required: true
);
Constructor Property Promotion (PHP 8.0+)¶
// Before
class ItemHandler
{
private XoopsDatabase $db;
private string $table;
public function __construct(XoopsDatabase $db, string $table)
{
$this->db = $db;
$this->table = $table;
}
}
// After (PHP 8.0+)
class ItemHandler
{
public function __construct(
private XoopsDatabase $db,
private string $table
) {}
}
Union Types (PHP 8.0+)¶
// Accept multiple types
public function setContent(string|array $content): void
{
if (is_array($content)) {
$content = implode("\n", $content);
}
$this->content = $content;
}
// Nullable shorthand
public function getUser(): User|null
{
return $this->user;
}
Match Expression (PHP 8.0+)¶
// Before: switch statement
switch ($status) {
case 'draft':
$label = 'Draft';
break;
case 'published':
$label = 'Published';
break;
case 'archived':
$label = 'Archived';
break;
default:
$label = 'Unknown';
}
// After: match expression
$label = match($status) {
'draft' => 'Draft',
'published' => 'Published',
'archived' => 'Archived',
default => 'Unknown'
};
Attributes (PHP 8.0+)¶
use Attribute;
#[Attribute]
class Route
{
public function __construct(
public string $path,
public array $methods = ['GET']
) {}
}
class ItemController
{
#[Route('/items', methods: ['GET'])]
public function index(): Response
{
// ...
}
#[Route('/items/{id}', methods: ['GET'])]
public function show(int $id): Response
{
// ...
}
}
Enums (PHP 8.1+)¶
// Before: class constants
class ItemStatus
{
public const DRAFT = 'draft';
public const PUBLISHED = 'published';
public const ARCHIVED = 'archived';
}
// After: native enums
enum ItemStatus: string
{
case Draft = 'draft';
case Published = 'published';
case Archived = 'archived';
public function label(): string
{
return match($this) {
self::Draft => 'Draft',
self::Published => 'Published',
self::Archived => 'Archived',
};
}
public function canEdit(): bool
{
return $this === self::Draft;
}
}
// Usage
$item->status = ItemStatus::Published;
echo $item->status->label(); // "Published"
Readonly Properties (PHP 8.1+)¶
class Item
{
public function __construct(
public readonly int $id,
public readonly string $title,
public readonly \DateTimeImmutable $created
) {}
}
$item = new Item(1, 'Title', new \DateTimeImmutable());
$item->title = 'New Title'; // Error: Cannot modify readonly property
Readonly Classes (PHP 8.2+)¶
readonly class ItemDTO
{
public function __construct(
public int $id,
public string $title,
public string $content,
public \DateTimeImmutable $created
) {}
}
Migration Patterns¶
Null Coalescing¶
// Before
$value = isset($array['key']) ? $array['key'] : 'default';
// After (PHP 7.0+)
$value = $array['key'] ?? 'default';
// Null coalescing assignment (PHP 7.4+)
$array['key'] ??= 'default';
Arrow Functions¶
// Before
$ids = array_map(function($item) {
return $item->id;
}, $items);
// After (PHP 7.4+)
$ids = array_map(fn($item) => $item->id, $items);
Spread Operator¶
// Array spread
$merged = [...$array1, ...$array2];
// Named argument spread
$config = ['size' => 50, 'maxlength' => 255];
$element = new XoopsFormText(
caption: 'Title',
name: 'title',
...$config
);
Code Compatibility Checker¶
flowchart TD
A[Run PHPStan] --> B{Issues Found?}
B -->|Yes| C[Review Deprecations]
C --> D[Update Code]
D --> A
B -->|No| E[Run PHP CS Fixer]
E --> F[Test with PHP 8.x]
F --> G{Tests Pass?}
G -->|No| H[Fix Issues]
H --> F
G -->|Yes| I[Deploy]PHPStan Configuration¶
# phpstan.neon
parameters:
level: 8
phpVersion: 80200
paths:
- class/
- src/
excludePaths:
- vendor/
reportUnmatchedIgnoredErrors: false
Running Analysis¶
# Install PHPStan
composer require --dev phpstan/phpstan
# Run analysis
./vendor/bin/phpstan analyse
# With specific PHP version
./vendor/bin/phpstan analyse --php-version=8.2
Common Fixes¶
String Access¶
Null Handling¶
// ❌ Error in PHP 8: strlen(null)
$length = strlen($value);
// ✅ Handle null explicitly
$length = strlen($value ?? '');
// or
$length = $value !== null ? strlen($value) : 0;
Array Functions¶
// ❌ Passing null to array functions
array_merge(null, $array);
// ✅ Ensure array type
array_merge($array1 ?? [], $array2);
Class Properties¶
// ❌ Dynamic properties deprecated in PHP 8.2
class Item
{
// No $title property declared
}
$item = new Item();
$item->title = 'Test'; // Deprecated warning
// ✅ Declare all properties
class Item
{
public string $title = '';
}