Design patterns implemented in Scala

Inspired by Design patterns implemented in Java

Introduction

Design patterns are formalized best practices that the programmer can use to solve common problems when designing an application or system. The classical design patterns are the 23 design patterns by GoF.

This project implements dozens of design patterns in Scala. The Scala language has several advanced features which make the implementations are different from other programming languages.

Design patterns are categorized into:

1. Creational
2. Structural
3. Behavioral
4. Other
5. Persistence

For each design pattern, it tags:

1. scala features indicates if the implementation uses scala language-specific features.
2. functional indicates if the design pattern can be implemented in functional-programming style.
3. Gang of four indicates if the design pattern is one of the classical 23 design patterns by GoF

Creational

Name	scala features	functional	Gang of four
abstract factory	no	no	yes
builder	no	no	yes
cake	yes(trait mix-in)	no	no
factory kit	no	yes	no
factory method	no	no	yes
prototype	no	no	yes
simple factory	yes(companion object)	no	no
singleton	yes(object)	no	yes
value object	yes(case class)	no	no

Structural

Name	scala features	functional	Gang of four
adapter	yes(implicit class)	no	yes
bridge	no	no	yes
composite	no	no	yes
decorator	yes(stackable trait)	no	yes
facade	no	no	yes
flyweight	no	no	yes
magnet	yes(implicit conversion)	no	no
proxy	no	no	yes
type classes	yes(impilict parameter)	no	no

Behavioral

Name	scala features	functional	Gang of four
chain of responsibility	yes(partial function)	yes	yes
command	no	yes	yes
loan	yes(structural type)	yes	no
mediator	no	no	yes
memento	no	no	yes
observer	no	no	yes
state	no	no	yes
strategy	no	yes	yes
template method	no	no	yes
visitor	no	yes	yes

Other

Name	scala features	functional	Gang of four
selfless trait	yes(companion trait)	no	no
monad	no	yes	no

Persistence

Name	scala features	functional	Gang of four
data access object	no	no	no
repository	no	no	no

Getting Started

Run sbt assembly to compile, run tests and package all sub-projects.

If you want to operate specific sub-project, use project command in sbt shell to switch sub-project:

> projects          // list all sub-projects
> project builder   // switch to 'builder' sub-project
> project all       // switch to 'all' project which including all sub-projects

License

This project is licensed under the terms of the Apache 2.0 license.