php

PHP

Runtime and versioning

• Run PHP 8.4 (active support) or 8.5 (latest stable). Never run EOL versions — no security patches
• declare(strict_types=1) at top of every file
• OPcache enabled in production. opcache.preload for warm startup on 8.0+
• JIT enabled for CPU-bound workloads: opcache.jit=tracing, opcache.jit_buffer_size=128M. Not beneficial for typical I/O-bound web apps — benchmark before enabling

Type system

• Type-hint all parameters, return types, and properties. No mixed — use union types (int|string) or generics via PHPDoc
• never return type for functions that always throw or exit
• readonly properties for value objects and DTOs (8.1+). readonly classes (8.2+) for fully immutable objects
• Asymmetric visibility (8.4+): public private(set) for properties readable everywhere but writable only within class
• Property hooks (8.4+): get/set hooks on properties — eliminates getter/setter boilerplate. Incompatible with readonly
• Intersection types (8.1+): Countable&Iterator. DNF types (8.2+): (A&B)|null
• Typed class constants (8.3+): const string VERSION = '1.0'
• #[Override] attribute (8.3+) on overriding methods — compiler-checked safety net
• Enums over constants for closed value sets (8.1+). Backed enums (string/int) for serialisation
• Named arguments for multi-param functions with non-obvious order. Not for all calls
• match over switch — exhaustive, no fall-through, returns value
• First-class callable syntax (8.1+): strlen(...) over Closure::fromCallable('strlen')

Modern syntax (8.4–8.5)

• new without parentheses for chaining (8.4+): new Collection()->filter()->map()
• Pipe operator (8.5+): $result = $value |> trim(...) |> strtolower(...) |> htmlspecialchars(...). Prefer over nested calls
• clone with (8.5+): $new = clone $obj with {name: 'updated'}. Preferred over manual clone + property set
• Static property asymmetric visibility (8.5+): same syntax as instance properties
• Lazy objects (8.4+): built-in lazy initialisation via ReflectionClass::newLazyProxy(). Use for expensive dependencies in DI containers
• Driver-specific PDO classes (8.4+): Pdo\Mysql, Pdo\Pgsql, Pdo\Sqlite — type-safe, IDE-friendly alternatives to generic PDO