PHP 8.1 Enums and Fibers — Complete Guide to Modern PHP Features
In this tutorial, you will learn about PHP 8.1 Enums and Fibers. We cover key concepts, practical examples, and best practices to help you master this topic.
PHP 8.1 introduced native enumerations (enums) for fixed value sets and fibers for cooperative multitasking, enabling cleaner code and concurrent execution patterns.
What You'll Learn
By the end of this tutorial, you'll create backed and pure enums, add methods to enum cases, use fibers for cooperative multitasking, and integrate fiber-based concurrency in PHP.
Why Enums and Fibers Matter
Enums replace stringly-typed constants with compiler-checked values. Fibers enable async-like patterns without external libraries, useful for concurrent I/O operations.
Real-World Use
An e-commerce platform uses enums for order status (Pending, Confirmed, Shipped, Delivered) and fibers to concurrently fetch product data from multiple suppliers.
Enum Fibers Path
flowchart LR
A[PHP 8 Features] --> B[Enums/Fibers]
B --> C[Readonly Classes]
B --> D[PSR Standards]
C --> E[Property Hooks]
B --> F{You Are Here}
style F fill:#f90,color:#fff
Pure Enums
Pure enums define cases without associated values.
<?php
enum OrderStatus {
case Pending;
case Confirmed;
case Shipped;
case Delivered;
case Cancelled;
}
function sendNotification(OrderStatus $status): void {
match ($status) {
OrderStatus::Confirmed => echo "Order confirmed\n",
OrderStatus::Shipped => echo "Order shipped\n",
OrderStatus::Delivered => echo "Order delivered\n",
default => echo "Status: {$status->name}\n",
};
}
sendNotification(OrderStatus::Shipped);
Backed Enums
Backed enums have scalar values (int or string) for database persistence.
<?php
enum UserRole: string {
case Admin = "admin";
case Editor = "editor";
case Viewer = "viewer";
public function label(): string {
return match ($this) {
self::Admin => "Administrator",
self::Editor => "Content Editor",
self::Viewer => "Read Only",
};
}
public static function fromDatabase(string $value): self {
return self::from($value);
}
}
$role = UserRole::from("editor");
echo $role->label();
echo $role->value;
Enum Methods
Enums can have methods, implement interfaces, and use traits.
<?php
interface HasColor { public function color(): string; }
enum PaymentMethod: string implements HasColor {
case CreditCard = "cc";
case DebitCard = "dc";
case PayPal = "pp";
case BankTransfer = "bt";
public function color(): string {
return match ($this) {
self::CreditCard => "#4A90D9",
self::DebitCard => "#7B68EE",
self::PayPal => "#003087",
self::BankTransfer => "#2E8B57",
};
}
public function isInstant(): bool {
return $this === self::CreditCard || $this === self::DebitCard;
}
}
echo PaymentMethod::PayPal->color();
echo PaymentMethod::CreditCard->isInstant() ? "Instant" : "Delayed";
Fiber Basics
Fibers are cooperative concurrency primitives that can suspend and resume execution.
<?php
function fetchData(string $url): string {
$fiber = new Fiber(function () use ($url): string {
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$result = curl_exec($ch);
curl_close($ch);
return $result;
});
return $fiber->start();
}
Fiber Scheduling
Multiple fibers can be scheduled to run concurrently, suspending with Fiber::suspend().
<?php
function fetchMultiple(array $urls): array {
$fibers = [];
$results = [];
foreach ($urls as $key => $url) {
$fibers[$key] = new Fiber(function () use ($url) {
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$result = curl_exec($ch);
curl_close($ch);
return $result;
});
$fibers[$key]->start();
}
foreach ($fibers as $key => $fiber) {
$results[$key] = $fiber->getReturn();
}
return $results;
}
Common Mistakes
1. Comparing Enums Incorrectly
Enums are objects. Use === for comparison, not == which may cause unexpected matches.
2. Serializing Backed Enums to Database Incorrectly
Use $enum->value for backing values and self::from() to reconstruct from the database.
3. Not Handling Fiber Throw
Call Fiber::throw() to rethrow exceptions from the fiber's context.
4. Creating Too Many Fibers
Each fiber has memory overhead. Limit concurrent fibers to a reasonable pool size.
5. Forgetting Enums Cannot Extend Other Classes
Enums cannot extend classes but can implement interfaces and use traits.
Practice Questions
1. What is the difference between pure and backed enums?
Pure enums have no associated values. Backed enums are backed by int or string values.
2. Can enums have methods?
Yes. Enums can have methods, implement interfaces, and use traits.
3. What is a fiber in PHP 8.1?
A cooperative concurrency primitive that can suspend execution and resume later.
4. How do you get the backing value of an enum case?
$enum->value returns the backing value. $enum->name returns the case name as a string.
5. Challenge: Create a role-based authorization system using enums.
<?php
enum Permission: string {
case Read = "read";
case Write = "write";
case Delete = "delete";
case Admin = "admin";
}
enum Role: string {
case Admin = "admin";
case Editor = "editor";
case Viewer = "viewer";
public function permissions(): array {
return match ($this) {
self::Admin => Permission::cases(),
self::Editor => [Permission::Read, Permission::Write],
self::Viewer => [Permission::Read],
};
}
public function has(Permission $perm): bool {
return in_array($perm, $this->permissions());
}
}
$role = Role::Admin;
echo $role->has(Permission::Delete) ? "Allowed" : "Denied";
FAQ
Mini Project: Enum-Based State Machine
Build a state machine using PHP 8.1 enums.
<?php
enum OrderState: string {
case Pending = "pending";
case Paid = "paid";
case Shipped = "shipped";
case Delivered = "delivered";
case Cancelled = "cancelled";
public function allowedTransitions(): array {
return match ($this) {
self::Pending => [self::Paid, self::Cancelled],
self::Paid => [self::Shipped, self::Cancelled],
self::Shipped => [self::Delivered],
self::Delivered => [],
self::Cancelled => [],
};
}
public function canTransitionTo(self $next): bool {
return in_array($next, $this->allowedTransitions(), true);
}
}
What's Next
PHP 8.2 Readonly Classes PHP 8.3 JSON Validation PHP 8.4 Property Hooks
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