Principles of Object Oriented Design

foundations_principles_development.mkd

Principles

• DRY ou Don't Repeat Yourself
• KISS ou Keep It Simple, Stupid!
• YAGNI ou You Ain't Gonna Need It!
• SOLID
• STUPID
• Law Of Demeter
• Tell, don't ask!

SOLID

• Single Responsability Principle
• Open/Close Principle
• Liskov Substitution Principle
• Interface Segregation Principle
• Dependency Inversion Principle

STUPID

• Singleton (Static)
• Tight Coupling
• Untestable
• Premature Optimization
• Indescriptive Naming
• Duplication

GRASP (General Responsibility Assignment Software Principles)

• Information Expert
• Creator
• Controller
• Low Coupling
• High Cohesion
• Polymorphism
• Pure Fabrication
• Indirection
• Protected Variations

Object Calisthenics

• Use only one level of indentation per method.
• Don't use the else keyword.
• Wrap all primitives and strings.
• Use only one dot per line.
• Don't abbreviate.
• Keep all entities small.
• Don't use any classes with more than two instance variables.
• Use first-class collections.
• Don't use any getters/setters/properties.

Sandi Metz’ rules for developers

http://robots.thoughtbot.com/post/50655960596/sandi-metz-rules-for-developers?utm_source=rubyweekly&utm_medium=email

• Classes can be no longer than one hundred lines of code.
• Methods can be no longer than five lines of code.
• Pass no more than four parameters into a method. Hash options are parameters.
• Controllers can instantiate only one object. Therefore, views can only know about one instance variable and views should only send messages to that object (@object.collaborator.value is not allowed).