My study notes for the various objected oriented refactoring techniques and design patterns. Includes code samples as well as written text explanations.
Note: Refactoring Guru is likely a much better resource than these notes.
Structural patterns explain how to assemble objects and classes into larger structures, while keeping the structures flexible and efficient.
| Pattern | Description |
|---|---|
| Composite Pattern | Compose objects into tree structures and then work with these structures as if they were individual objects. |
| Adapter Pattern | Allows objects with incompatible interfaces to collaborate. |
| Decorator Pattern | Dynamically attach new behaviours to objects by placing these objects inside special wrapper objects that contain the behaviours. |
Behavioral patterns take care of effective communication and the assignment of responsibilities between objects.
| Pattern | Description |
|---|---|
| Strategy Pattern | Extract varying behaviours into separate classes and allow these to be changed in a context object dynamically. |
| State Pattern | Allows objects to alter its behaviour when its internal state changes. |
| Observer Pattern | Define a subscription mechanism to notify multiple objects about any events that happen to an observed object. |
| Template Method Pattern | Define the skeleton of an algorithm in the superclass but lets subclasses override specific steps of the algorithm without changing its structure. |
| Visitor Pattern | Separate algorithms from the objects on which they operate. Allow new behaviours to be added to existing classes without modifying them (mostly). |
Creation patterns provide various object creation mechanisms that increase flexibility and code reuse.
| Pattern | Description |
|---|---|
| Factory Method | Provide an interface for creating objects in a superclass, but allows subclasses to alter the type of objects that will be created. |
| Abstract Factory Pattern | Produce familes of related objects without specifying their concrete classes. |
| Builder Pattern | Construct complex objects step by step. |
| Singleton Pattern | Ensure that a class has only one instance, while providing a global access point to this instance. |