[DesignPattern] About

A bad design:
- Rigidity
- Fragility
- Immobility

Principles:
- Open Close Principle
      - open for extensions
      - close for modifications
- Dependency Inversion Principle
       - high level modules should not depend on low level modules
       - abstract should not depend on details
- Interface Segregation Principle
       - interfaces should be minimal and complete
- Liskov's Substitution Principle
       - derives types must be completely substitutable for their base type

Classification:
- purpose

• creational
• structural (Structural patterns are concerned with how classes and objects are composed to form larger structures.)
  
• behavioral

- scope

• class
• object