Object Oriented Programming Resources/Head First Design Pattern Recaps

Design Principles

• Identify the aspects of your application that vary and separate them from what stays the same. (1/9)
• Program to an interface, not an implementation. (1/11)
• Favor composition over inheritance. (1/23)
• Strive for loosely coupled designs between objects that interact. (2/53)
• Classes should be open for extension, but closed for modification. (3/86)

Patterns (by order)

• The Strategy Pattern defines a family of algorithms, encapsulates each one, and makes them interchangeable. Strategy lets the algorithm vary independently from clients that use it.
• The Observer Pattern defines a one-to-many dependency between objects so that when one object changes state, all of its dependents are notified and updated automatically.
• The Decorator Pattern attaches additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.
• The Factory Method Pattern defines an interface for creating an object, but lets subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.