Enums, introduced in PHP 8.1, provide a way to define a set of possible values for a type, offering a structured and type-safe alternative to constants. They are ideal for situations where you need to represent a fixed set of options, such as user roles, status codes, or any predefined list of values.
Basic Enum Syntax:
To declare an enum in PHP 8.1, you use the enum keyword:
enum UserRole {
case Admin;
case Editor;
case Subscriber;
}
Here, UserRole defines three possible values: Admin, Editor, and Subscriber.
Using Enums
Enums can be used as types in function parameters, ensuring that only the defined values are allowed:
function getUserPermissions(UserRole $role): array {
return match($role) {
UserRole::Admin => ['create', 'edit', 'delete'],
UserRole::Editor => ['create', 'edit'],
UserRole::Subscriber => ['read'],
};
}
$role = UserRole::Admin;
$permissions = getUserPermissions($role);
This setup guarantees that only valid roles can be passed to the function.
Backed Enums
Enums can also be associated with scalar values, like strings or integers:
enum Status: string {
case Active = 'active';
case Inactive = 'inactive';
case Suspended = 'suspended';
}
echo Status::Active->value; // Outputs: 'active'
Backed enums are useful when you need to map enum values to database entries or other external systems.
Enum Methods
PHP enums can contain methods for more complex logic:
enum OrderStatus {
case Pending;
case Shipped;
case Delivered;
public function isFinal(): bool {
return $this === self::Delivered;
}
}
Here, OrderStatus includes a method isFinal to check if the status is Delivered.
Conclusion:
Enums in PHP 8.1 bring type safety and clarity to your code by grouping related constants. They are especially useful when you need to ensure that a variable can only hold a predefined set of values, making your code more robust and easier to maintain.
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