Immutable Value Objects with PHP 8.2+ Readonly Properties & Classes

<?php

declare(strict_types=1);

namespace App\Domain\ValueObjects;

use InvalidArgumentException;

readonly class Money
{
    public function __construct(
        public int $amountInCents,
        public string $currency = 'KES'
    ) {
        if ($this->amountInCents < 0) {
            throw new InvalidArgumentException("Amount cannot be negative.");
        }
    }

    public static function fromDecimal(float $amount, string $currency = 'KES'): self {
        return new self((int)round($amount * 100), $currency);
    }

    public function toDecimal(): float {
        return $this->amountInCents / 100;
    }
}