What is this?

Example Implementations of Design Patterns all content is from: Head First Design Patterns (wonderful book :))

Why the ****

Just for me to learn and remember. Go away...

Starting Point:

let's assume the is a pizza store and it looks like this: doc

Benefits of Refactorings

(just browse the commits to get the different stages)

Simple Factory: (doc)

• separated what varies (pizza creation) from what stays the same (making the pizza)
• PizzaStore has no dependencies to concrete Pizzas anymore
• Tests don't require the PizzaStore to work with a certain Pizza (or all of them)
• Tests can inject stubs easily to test PizzaStores logic
• PizzaStore now follows the Open-Closed principle

Factory Method: (doc)

• separate usage and implementation of the product
• ensure that same logic is applied to all products (dev doesn't need to remember)
• logic and product instantiation can still be tested separately

Abstract Factory: (doc)

• define creation of families of related or dependent products
• decouple logic from actual factories (easy replacement of factories)
• decouple logic applied on objects from their instantiation (same logic applied on all products)