Observer: Reacting to Order Events
Let email, analytics and loyalty react to “order placed” without the order knowing them. Lesson 8 of Level 4: Design Patterns. Based on Design Patterns.
Level 4 · Design Patterns · Lesson 8 of 13
Let email, analytics and loyalty react to “order placed” without the order knowing them.
Continue learning
- Facade & Proxy: Simple Front Doors and Smart Stand-ins — Previous lesson
- Command: Refunds, Retries and Queued Work as Objects — Next lesson
- Level 4: Design Patterns — Back to the level
Try it hands-on
- Design Pattern Playground — Add payment methods, discounts and order states to ShopFlow with and without patterns; count the classes you had to edit.
All lessons in Design Patterns
- Patterns Are Answers to Recurring Pain
- Strategy: Pluggable Payment Methods
- Factory Method & Abstract Factory: Creating the Right Thing
- Builder, and Why Singleton Is Usually a Trap
- Adapter: Taming Third-Party Payment Gateways
- Decorator: Adding Behaviour Without Touching the Core
- Facade & Proxy: Simple Front Doors and Smart Stand-ins
- Observer: Reacting to Order Events
- Command: Refunds, Retries and Queued Work as Objects
- State: An Order Lifecycle Without the Giant Switch
- Template Method: One Checkout Skeleton, Many Variations
- Chain of Responsibility: Validation & Fraud Pipelines
- Composite, Bridge, Mediator, Iterator & Prototype