Open/Closed Principle in WordPress Architecture

WordPress plugins rarely collapse because of complexity. They collapse because of change. New payment gateway. New notification channel. New integration. New business rule. And suddenly — you are modifying the same class again. That’s exactly what the Open/Closed Principle (OCP) is designed to prevent. What Open/Closed Principle Really Means Software entities should be open for extension, but closed for modification. It does not mean your code never changes. It means: Core behavior remains stable. New functionality is added by extension — not by editing existing logic. If every new feature requires touching old code, your architecture is fragile. A Typical WordPress Anti-Pattern php class PaymentProcessor { public function process(string $method, float $amount): void { if ($method === 'paypal') { // PayPal logic } if ($method === 'stripe') { // Stripe logic } if ($method === 'bank') { // Bank transfer logic } } } Works fine. Until business says: Add Apple Pay Add crypto Add installment