Method demo

examples/demo.php:354–371

()

class GuardClauseDemo
{
    public function demo(): void
    {
        $subject = pickRockOrBanana();            // Rock|Banana
        if (!$subject instanceof Banana) {
            return;                               // early return — guard clause
        }
        $subject->peel();                         // narrowed to Banana after guard

        $candidate = pickRockOrBanana();          // Rock|Banana
        if ($candidate instanceof Rock) {
            throw new Exception('no rocks');       // early throw — guard clause
        }
        $candidate->peel();                       // narrowed to Banana (Rock excluded)

        $unknown = getUnknownValue();
        if (!$unknown instanceof Rock) return;    // single-statement guard (no braces)
        $unknown->crush();                        // narrowed to Rock
    }

    /** Positive instanceof + early return on a mixed parameter. */
    public function mixedGuard(mixed $value): void