View source for 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)
* Depend upon abstractions.  Do not depend upon concrete classes. (4/139)

== 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.
## The Abstract Factory Pattern provides an interface for creating families of related or dependent objects without specifying their concrete classes.