Page Comparison

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1. DRY (Don't Repeat Yourself)
   http://en.wikipedia.org/wiki/Don%27t_repeat_yourself
2. Separation of Concerns
   http://en.wikipedia.org/wiki/Separation_of_concerns
3. Encapsulation
   http://en.wikipedia.org/wiki/Encapsulation_(object-oriented_programming)
4. Dependency Abstraction through Interfaces
   Dependencies between classes should be through interfaces not classes.
5. SOLID
   http://en.wikipedia.org/wiki/SOLID_(object-oriented_design)
   1. Single Responsibility
      http://en.wikipedia.org/wiki/Single_responsibility_principle
   2. Open/Closed
      http://en.wikipedia.org/wiki/Open/closed_principle
   3. Liskov Substitution
      http://en.wikipedia.org/wiki/Liskov_substitution_principle
   4. Interface Segregation
      http://en.wikipedia.org/wiki/Interface_segregation_principle
   5. Dependency Inversion - a superset of (Service Locator, Factory, Dependency Injection)
      http://en.wikipedia.org/wiki/Dependency_inversion_principle