Modern PHP 8.x Development

Before writing code

Fetch live docs: Web-search site:php.net manual migration for the latest PHP migration guide and new features. Check https://www.php.net/releases/ for current supported versions.

PHP 8.0 Features

Constructor Property Promotion

Declare and assign properties directly in the constructor signature — eliminates boilerplate. Useful in WooCommerce extension classes.

Named Arguments

Call functions with parameter names: array_slice(array: $arr, offset: 2). Improves readability for functions with many parameters.

Match Expressions

Type-safe switch replacement that returns a value. No fall-through, strict comparison. Better than switch for value mapping.

Union Types

int|string in parameter and return types. Allows multiple type declarations.

Nullsafe Operator

$obj?->method()?->property — short-circuits to null if any part is null. Replaces nested null checks.

Attributes

Native metadata annotations: #[Route('/path')], #[Override]. Replace docblock annotations with first-class language support.

PHP 8.1 Features

Enums

First-class enumerations — backed (string/int) and unit enums. Perfect for status codes, types, categories. Use backed enums for database/API values.

Readonly Properties

public readonly string $name — can only be set once (usually in constructor). Enforces immutability.

Fibers

Lightweight concurrency primitives — PHP-level coroutines. Foundation for async frameworks.

Intersection Types

TypeA&TypeB — value must satisfy ALL types. Useful for ensuring a parameter implements multiple interfaces.

First-class Callable Syntax

strlen(...) creates a Closure from a function. Cleaner than Closure::fromCallable('strlen').

PHP 8.2 Features

Readonly Classes

readonly class Dto { ... } — all properties are implicitly readonly. Perfect for Data Transfer Objects and value objects.

Deprecated: Dynamic Properties

Creating properties not declared in the class is deprecated. Always declare properties.

Standalone Types

true, false, null as standalone types in declarations.

Constants in Traits

Traits can now define constants.

PHP 8.3 Features

Typed Class Constants

const string NAME = 'value'; — type-safe constants. Strengthens contract enforcement.

#[\Override] Attribute

Documents that a method intentionally overrides a parent method. Compiler error if the parent method doesn't exist.

json_validate() Function

Validate JSON without decoding — faster than json_decode + error check.

Dynamic Class Constant Fetch

$class::{$constant} — dynamic constant access.

PHP 8.4 Features

Property Hooks

Define get/set behavior directly on properties:

public string $name {
    set => strtolower($value);
    get => ucfirst($this->name);
}

Asymmetric Visibility

public private(set) string $name — readable publicly, writable only privately.

PHP for WooCommerce Specifically

Type Safety

• Use strict types: declare(strict_types=1); in all files
• Type all parameters, return types, and properties
• Use union types for nullable: ?string or string|null

Value Objects

Use readonly classes for DTOs and value objects — common in service layers.

Enums for Status Codes

Replace string/int constants with backed enums for order statuses, product types, etc.

WordPress Coding Standards Note

WPCS uses tabs for indentation and Yoda conditions ('value' === $var). This differs from PSR-12 (spaces, non-Yoda). When writing WooCommerce extensions, follow WPCS; for standalone PHP libraries, follow PSR-12.

Best Practices

• Always use declare(strict_types=1);
• Type everything: parameters, returns, properties, constants
• Use readonly for immutable data
• Use enums instead of string/int constants
• Use match instead of switch for value mapping
• Use named arguments for clarity with many-parameter functions
• Use #[\Override] when overriding parent methods
• Follow WordPress Coding Standards (WPCS) for WooCommerce extensions

Fetch php.net docs for exact syntax and behavior of new features before using them.