Design Pattern
Each pattern describes a problem which occurs over and over again … and then describes the core of the solution to that problem, in such a way that you can use this solution a million times over, without doing it the same way twice. @Christopher Alexander
目前有26種主要的設計模式，又可以分成三大類
- Creational：設計類別或物件的實例化
- Structural：類別的架構，設計的目的是增加類別的功能性、可擴充性
- Behavioral：類別的行為，包含與其他物件互動的方式
為什麼要使用
- 保持軟體彈性
- 降低耦合度
- 提高重複可用性
- 提升解決軟體問題的能力
Creational
| Name | Description |
|---|---|
| Abstract Factory | 宣告類別但不實做內容 |
| Builder | Separates object construction from its representation |
| Factory Method | Creates an instance of several derived classes |
| Object Pool | Avoid expensive acquisition and release of resources by recycling objects that are no longer in use |
| Prototype | A fully initialized instance to be copied or cloned |
| Singleton | A class of which only a single instance can exist |
Structural
| Name | Description |
|---|---|
| Adapter | Match interfaces of different classes |
| Bridge | Separates an object’s interface from its implementation |
| Composite | A tree structure of simple and composite objects |
| Decorator | Add responsibilities to objects dynamically |
| Facade | A single class that represents an entire subsystem |
| Flyweight | A fine-grained instance used for efficient sharing |
| Private Class Data | Restricts accessor/mutator access |
| Proxy | An object representing another object |
Behavioral
| Name | Description |
|---|---|
| Chain of responsibility | A way of passing a request between a chain of objects |
| Command | Encapsulate a command request as an object |
| Interpreter | A way to include language elements in a program |
| Iterator | Sequentially access the elements of a collection |
| Mediator | Defines simplified communication between classes |
| Memento | Capture and restore an object’s internal state |
| Null Object | Designed to act as a default value of an object |
| Observer | 當被觀察物件異動時通知多個物件觸發事件 |
| State | Alter an object’s behavior when its state changes |
| Strategy | Encapsulates an algorithm inside a class |
| Template method | Defer the exact steps of an algorithm to a subclass |
| Visitor | Defines a new operation to a class without change |
https://cs.lmu.edu/~ray/notes/designpatterns/
https://www.freecodecamp.org/news/the-basic-design-patterns-all-developers-need-to-know/