Intro to OO Modeling and Design

Speaker: Brian Kotek

What is Good Design:

• Elegant
• Simple
• Robust
• Flexible
• Appropriate

Design == Trade offs

Its all about Art and Science

Where To Start???

• Requirements and Use Cases
• Identify Nouns and Verbs: Nouns(Costumer) Verbs (LogIn)

Commonality and Variability
Wine, Restaurants, Regions

Design Principles

• Single Responsibility Principle (Do one thing, but do it well)
• Dry (Dont repeat your self)
• Open / Closed (open for extension but closed for modification)
• Tell, Dont Ask
• Law of Demeter (employee.pay())
• Design to Interfaces
• Encapsulation (Do in cfc), data, type, reveal by need
  

Indicator of Design Quality

• Loose Coupling / Connascence (Objects should not depends on a lot of other objects, keep dependencies small)
• Interface Coupling (user.addUser() )
• Inheritance Coupling (price = super.price * discount)
  
• Cohesion
• Class Reference Set (You have to know how many objects depends of that specific object)
  
• Testability

Theory Meets Real Life

• Is there Such a Thing? Very Difficult

Olhar os softwares de XML, OO e outros da Altova INC

www.briankotek.com/blog
www.alagad.com
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