when()

Use when() when a complete validator should be active only for certain object states. The closure receives the object being validated and must return a boolean:

use Fynix\Rule;

$rule = Rule::for($order)
    ->string('companyName')
    ->min(10)
    ->when(static fn (Order $order): bool => $order->shippingMethod === 'business');

When the closure returns false, the validator returns no errors and skips its type, length, requiredness, and related-field checks. The condition is evaluated during validation, so it sees the current object state.

Use requiredIf(), requiredUnless(), prohibitedIf(), or prohibitedUnless() when only field presence or prohibition is conditional. Those methods also accept closure predicates.